J Head Trauma Rehabil Vol. 31, No. 3, pp. E32–E41 c 2016 Wolters Kluwer Health, Inc. All rights reserved. Copyright
Use of Visual Cues by Adults With Traumatic Brain Injuries to Interpret Explicit and Inferential Information Jessica A. Brown, PhD; Karen Hux, PhD; Kelly Knollman-Porter, PhD; Sarah E. Wallace, PhD Objective: Concomitant visual and cognitive impairments following traumatic brain injuries (TBIs) may be problematic when the visual modality serves as a primary source for receiving information. Further difficulties comprehending visual information may occur when interpretation requires processing inferential rather than explicit content. The purpose of this study was to compare the accuracy with which people with and without severe TBI interpreted information in contextually rich drawings. Participants: Fifteen adults with and 15 adults without severe TBI. Design: Repeated-measures between-groups design. Main Measures: Participants were asked to match images to sentences that either conveyed explicit (ie, main action or background) or inferential (ie, physical or mental inference) information. The researchers compared accuracy between participant groups and among stimulus conditions. Results: Participants with TBI demonstrated significantly poorer accuracy than participants without TBI extracting information from images. In addition, participants with TBI demonstrated significantly higher response accuracy when interpreting explicit rather than inferential information; however, no significant difference emerged between sentences referencing main action versus background information or sentences providing physical versus mental inference information for this participant group. Conclusions: Difficulties gaining information from visual environmental cues may arise for people with TBI given their difficulties interpreting inferential content presented through the visual modality. Key words: comprehension, high-context images, inferences, traumatic brain injury
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OMPREHENDING CONTENT EXPRESSED in communicative situations often involves combined linguistic and visual processing skills and requires interpreting inferred as well as explicit information. On a purely linguistic level, understanding explicit intent requires accurate interpretation of literal meanings associated with a speaker’s utterances. Fully comprehending communicative intent typically extends beyond literal linguistic interpretation, however, and requires understanding implied content as well as nonlinguistic visual information present during interactions.1 Thus, attending solely to linguistic content is rarely sufficient. Various researchers have labeled communicative expressions requiring processing beyond linguistic interpretation as cognitive inferences2 or elaborative
Author Affiliations: Department of Special Education and Communication Disorders, University of Nebraska-Lincoln, Lincoln, Nebraska (Dr Brown, Dr Hux); Department of Speech Pathology and Audiology, Miami University, Oxford, Ohio (Dr Knollman-Porter); and Department of Speech-Language Pathology, Duquesne University, Pittsburg, Pennsylvania (Dr Wallace). The authors declare no conflicts of interest. Corresponding Author: Jessica A. Brown, PhD, Department of Special Education and Communication Disorders, University of Nebraska-Lincoln, 350 Barkley Memorial Center, Lincoln, NE 68583 ([email protected]). DOI: 10.1097/HTR.0000000000000148
inferences.3,4 Accurate cognitive or elaborative inference interpretation depends on information integration from multiple sources including linguistic (eg, words and phrases), paralinguistic (eg, inflection, intonation, and prosody), extralinguistic (eg, gestures, facial expressions, and body position), and nonlinguistic (eg, setting or context) content.1,5 This information integration necessitates the use of substantial cognitive processing resources, attention to details, accessing world knowledge, and linking stated information to contextual cues.2–4 Cognitive processing and sensory integration deficits experienced by individuals with traumatic brain injury (TBI) are of particular concern with regard to interpreting communicative intents. A primary brain function is integrating and analyzing sensory information to determine appropriate responses. Traumatic brain injury frequently disrupts this function leaving individuals with impaired sensory perception and cognition.6 The visual system in particular is highly susceptible to damage, with greater than 50% of people with severe TBIs experiencing long-term visual-perceptual deficits directly affecting information processing.7,8 Given that the human visual system mediates 80% of perception, learning, cognition, and daily activities,9 processing information through this sensory modality is of particular importance.
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Use of Visual Cues by Adult With TBI Visual-perceptual impairments associated with TBI typically appear in conjunction with persistent cognitive challenges.6–12 Combined visual-perceptual and cognitive impairments may be particularly problematic when the visual modality serves as a primary source for receiving communicative content.13–16 Such situations occur whenever speakers convey information through gestures, facial expressions, tone of voice, or body movements. Additional communicative information comes from visual cues provided by the physical setting and context in which an interaction occurs. Deriving extralinguistic and paralinguistic information such as a communication partner’s feelings, expectations, wants, or beliefs during conversational interactions is a concept termed “Theory of Mind.” Considerable research exists about the Theory of Mind deficits people with TBI exhibit when attempting to integrate information from multiple sources to interpret communicative intents.17–20 Most individuals with severe TBIs display cognitivecommunication deficits as a chronic condition.21 Because most do not have concomitant aphasia,22–24 the expectation is that they will perform accurately and efficiently on tasks requiring literal message interpretation. However, as soon as one considers the communicative context, inferential nature of communication, and need to attend to and interpret visual cues, it is apparent that accurate message interpretation requires more than literal decoding. Confirmation of this comes from research showing that most people with cognitivecommunication deficits following severe TBI accurately derive explicit meaning from written or spoken communications but may have difficulty interpreting inferential information.4,5,15,25–27 Individuals with TBI may have particular difficulty ascertaining information from visual cues. Difficulty may arise when attempting to derive information from static images due to the lack of movement cues and the differential manner and location in which the brain processes static versus dynamic stimuli.1,15,28–30 Because static images provide less information than dynamic images, processing and interpreting depicted information may be more difficult regardless of neurological status; however, adults without neurological injuries do not exhibit difficulty extracting content from static stimuli. The same is not true for people with TBI, but, to date, researchers do not know why this distinction occurs. One possibility is that attending to and integrating information from an image background as well as from primary image content may exceed the capabilities of people with TBI. This question was the motivation for this study. CURRENT STUDY A failure to attend adequately to and integrate fully available visual content may contribute to challenges
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people with TBI experience when constructing meaning from static images. This study’s purpose was to explore this possibility by determining the accuracy with which people with and without severe TBI matched written sentences relaying either explicit or inferred information to contextually rich drawings. To differentiate processing of various image components, the researchers included 2 types of explicit stimulus sentences—ones referencing a main character or event and ones referencing background or contextual details—as well as inferential stimulus sentences requiring the integration of main and background information to ascertain mental or physical inferences. Objectives The research objectives were to evaluate whether: 1. adults with and without TBI differ in their accuracy of selecting static, contextually rich images to match written content. The researchers hypothesized that adults with TBI would achieve poorer accuracy than their peers given the attention, information processing, and visual integration difficulties present within this population; 2. adults with TBI achieve higher accuracy scores when interpreting explicit versus inferential information associated with images. The researchers hypothesized that, in accordance with previous studies, adults with TBI would achieve lower scores when interpreting inferential information despite the support of contextually rich images; 3. adults with TBI achieve higher accuracy scores when interpreting sentences conveying main character/event than background information about images. Given a potential lack of attention to detail by participants with TBI, the researchers hypothesized better performance given main character/event than background information sentences; 4. adults with TBI achieve differing accuracy scores when interpreting physical versus mental inferences associated with images. The researchers hypothesized that adults with TBI would perform poorer when interpreting mental inferences given the widespread prevalence of Theory of Mind deficits associated with brain injury. METHOD Participants Participants included 15 adults with TBI and 15 ageand education-matched control participants without neurological impairments. All participants were native American English speakers and reported no developmental language or cognitive impairments. One participant was African American, and the remaining 29 were Caucasian. www.headtraumarehab.com
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Participants passed vision and motor screenings to ensure adequate capabilities to view and select experimental stimuli. Screening procedures required participants to locate and manually touch 9, 18-point font X’s appearing in various locations on a touch screen monitor and 5 details depicted in 2 high-context images similar in size and type to those presented in experimental tasks. Participants with TBI The ages of the 12 male and 3 female participants with TBIs ranged from 21 to 53 years (M = 37.47, SD = 9.55). Participants with TBI had education levels ranging from 12 to 18 years (M = 13.80, SD = 1.93). They were between 3 and 311 months postinjury (M = 133.33, SD = 128.48) and met criteria for having sustained severe initial injuries—that is, injuries causing at least 24 hours of lost consciousness and more than 1 week of posttraumatic amnesia.31 Injury severity was determined through self-report and confirmed by a caregiver or member of each participant’s rehabilitative team. At the time of study completion, 7 participants resided at a transitional rehabilitation program, 3 resided in an assisted living facility, and 5 lived semi-independently within the community. Administration of the Wide Range Achievement Test—4 (WRAT-4)32 reading subtest confirmed that all participants with TBI could decode words at or above third grade level (range: 36-52, M = 45.20, SD = 4.51)—that is, above the level of written experimental stimuli. Administration of the Western Aphasia Battery— Revised33 Aphasia Quotient confirmed that no participant with TBI had aphasia (ie, Aphasia Quotient scores ≥93.8; M = 97.73, SD = 1.83). The researchers also administered the Executive Function (EF) and Visual Spatial (VS) Domain subtests of the Cognitive-Linguistic Quick Test (CLQT)34 to provide descriptive information about current cognitive and visual processing abilities; these subtest results did not determine study eligibility. Scores for the CLQT EF Domain ranged from 12 to 35 of 40 possible points (M = 24.07, SD = 6.55). Seven of the participants with TBI achieved CLQT EF Domain scores within normal limits (ie, more than 24 points); 4 scored within the mild severity range (ie, between 20 and 23 points), 3 scored within the moderate severity range (ie, between 16 and 19 points), and 1 displayed severe deficits (ie, less than 15 points). Scores for the VS Domain ranged from 54 to 99 of 105 possible points (M = 77.47, SD = 13.19). Seven participants scored within normal limits (ie, 82 points or more), and 8 demonstrated mild deficits (ie, between 52 and 81 points). The WRAT-4 reading subtest and the CLQT EF and VS Domain subtest scores provided a means of correlating standardized test and experimental task performances of participants with TBI. Demographic and
assessment data for each participant with TBI appear in Table 1. Participants without TBI Participants without TBIs included 13 males and 2 females with ages ranging from 20 to 59 years (M = 33.33, SD = 13.67) and education levels ranging from grades 11 to 18 (M = 14.00, SD = 2.14). T test computations confirmed no significant age or education differences between participant groups, age: t28 = 0.96, P = .345; education: t28 = 0.27, P = .790. Administration of the WRAT-4 reading subtest confirmed that all participants without TBI could read at or above the third grade level (range: 35-57, M = 48.53, SD = 6.10). T test computation confirmed no significant word decoding difference between participant groups, t28 = 1.708, P = .099. To validate that participants without TBI had normal cognitive functioning, the researchers administered the Mini Mental State Exam.35 All participants without TBI achieved scores of 28 or better on the 30-point measure (M = 29.80, SD = 0.56). Materials Study materials included digital copies of Norman Rockwell drawings (www.Saturdayeveningpost.com) and 4 types of written sentences. Details about selecting and preparing stimulus images and sentences appear in Wallace et al.36 The researchers selected colored Norman Rockwell drawings as pictorial stimuli because of the complexity and high context of the images. In total, the researchers used 133 copies of Norman Rockwell drawings as the target and foil stimuli. Of these, 121 comprised experimental stimuli, and 12 comprised practice stimuli. The researchers systematically grouped images into sets of 4 for presentation on a touch screen monitor within a 2 × 2 grid. Each stimulus set contained 1 Norman Rockwell drawing as the target image and 3 Norman Rockwell drawings as foils. The researchers systematically alternated image location within the grid so that target images appeared an equal number of times in each position. In addition, the researchers systematically selected foil images to group with each target image. Foil images met the following criteria: (1) at least 1 image contained a character (eg, boy or woman) matching the target image main character; (2) if the stimulus sentence—as described below—corresponding to a target image mentioned an object, at least 1 foil image contained a matching object; (3) if the corresponding sentence indicated a location, at least 1 foil image contained a matching location; and (4) if the corresponding stimulus sentence described an action or state of being, at least 1 foil image had a matching action or state of being.
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Use of Visual Cues by Adult With TBI TABLE 1
Demographic data and standardized testing results for participants with TBI
Age (y)
Highest level of education
Time postonset of injury (mo)
1
47
18
187
2 3 4 5 6 7
39 43 21 26 21 53
16 16 14 16 14 12
310 311 20 161 14 7
8 9 10 11 12 13 14 15
35 45 34 39 33 35 47 44
14 12 12 14 13 12 12 12
5 7 3 47 296 221 105 306
Participant
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Mechanism of injury Bicycle accident MVA MVA MVA Sports injury Sports injury Bicycle accident MVA Fall MVA Blow to head MVA MVA MVA MVA
WRAT-4 Tan Reading subtesta
CLQT Executive Functioning Domainb
CLQT Visual Spatial Domainc
49
32
99
46 50 52 41 47 43
23 23 28 35 26 21
83 78 90 93 67 83
38 43 48 44 36 50 46 45
12 16 22 28 18 30 30 17
59 54 71 80 62 88 85 70
Abbreviation: CLQT, Cognitive-Linguistic Quick Test; MVA, motor vehicle accident; WRAT-4, Wide Range Achievement Test—4. a Maximum score = 57. b Maximum score = 40. c Maximum score = 105.
The researchers paired each of 60 target images with an active sentence. Forty of the written sentences comprised the explicit stimuli and required extraction of information either about the image main character (n = 20) or a background detail (n = 20). The remaining 20 sentences comprised the inferential stimuli and required extraction of information regarding a physical (n = 10) or mental (n = 10) inference. Physical inferences reported an assumed action or location of a depicted event; mental inferences reported an assumed internal belief, emotion, feeling, or desire of depicted character(s). Stimulus sentences appeared above the 2 × 2 grid displaying the target and foil images on the touch screen monitor. The print was in 48-point white font on a black screen background. Stimulus sentences across the 4 conditions included 4 to 9 words each (M = 6.43, SD = 1.28) and did not differ significantly in number of words, F3,56 = 2.330, P = .084. The researchers computed reading grade level and ease for the target sentences using Flesch-Kincaid Readability formulas.37 Flesch Reading Ease scores ranged between 91.1 and 97.7 out of 100 possible points for each sentence condition, with an average score of 93.3 across all sentence stimuli. Reading Grade Level estimates ranged from 1.1 to 2.1, with an average of grade 1.8 across all stimuli. Computation of 2 analysis of variances confirmed no significant differences among the 4 sentence sets regarding Reading Ease, F3,56 = 1.118, P =
.350, or Reading Grade Level, F3,56 = 0.858, P = .468. Examples of sentence stimuli appear in Table 2. Procedures Participants completed all study activities within 1 session lasting less than 1 hour. The researchers first administered standardized assessments and screening measures. Once a potential participant demonstrated visual, motor control, and word decoding skills adequate for the experimental task, he or she completed practice and experimental trials. Presentation of grid displays of target and foil images and associated written sentence stimuli was controlled using Direct RT by Empirisoft (New York, NY) and presented either on a 12-inch or a 14inch touch screen monitor depending on data collection site. Practice trials appeared in the same order across participants; however, experimental trials appeared in a unique random order for each participant. Experimental task completion was self-paced and required less than 15 minutes. The researchers instructed participants they could take short breaks during the experimental task, as needed; however, no participant requested a break. Participants viewed 3 practice trials presenting written and pictorial stimuli indicative of the main character/ event condition before performing the experimental task. All participants completed practice trials with 100% accuracy, thus suggesting comprehension of the task. www.headtraumarehab.com
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JOURNAL OF HEAD TRAUMA REHABILITATION/MAY–JUNE 2016
Example stimulus for each sentence type
Experimental condition Explicit Inferential
Attention focus
Example stimulus
Main action Background Physical inference Mental inference
The man is on the roof The map is hanging on the wall The boy is running away from home The girl is hopeful about winning
The examiner provided each participant with feedback regarding practice trial performance. Following this, participants completed all 60 experimental trials. To perform the experimental task, participants first touched a “go” icon. This icon activated simultaneous presentation of the 2 × 2 grid containing 1 target and 3 foil images and the associated written stimulus sentence. Participants touched the image that best matched the written sentence to indicate selection of a response. Once a participant selected an image, the stimulus screen returned to the “go” icon. These procedures repeated until the participant had viewed and selected responses for all 60 experimental trials. No performance feedback was provided.
participant group through computation of paired t tests. To control for possible error due to multiple comparisons, the researchers applied a Bonferroni correction with an α-level of 0.01 for all between- and withingroup post hoc analyses. In addition, as appropriate, the researchers evaluated correlations between participants’ total accuracy percentages, explicit accuracy percentages, inferential accuracy percentages, CLQT EF Domain scores, CLQT VS Domain scores, and WRAT-4 reading scores to examine the contribution of specific cognitive functions to task performance. RESULTS Total response accuracy
Data analysis The researchers measured response accuracy for each experimental trial through Direct RT. Response accuracy reflected the percentage of correctly selected target images for each experimental condition. The researchers tested between-group violation of the homogeneity assumption for total response accuracy. Computation of the Levene Test of Equality of Variances38 revealed a homogeneity violation, F = 16.018, P = .000; therefore, further total response accuracy analysis involved nonparametric statistics through computation of a Mann-Whitney U test. The researchers then analyzed significant differences between explicit and inferential stimulus conditions separately for each
Table 3 displays the mean percentage correct, standard deviation, and score range for each participant group across stimulus conditions. Participants with TBI collectively achieved an average total accuracy score of 81.08% across all stimulus items (SD = 12.15). Participants without TBI achieved higher and less variable average total accuracy scores than participants with TBI (M = 98.25%, SD = 1.62). The Mann-Whitney U test computation confirmed a significant total accuracy score difference between groups, U = 5.50, P < .0001. Computation of a correlation coefficient between total accuracy scores and testing and demographic information for participants with TBI revealed a significant linear relation only between total accuracy and CLQT EF
TABLE 3 Ranges, mean response accuracy percentages, and standard deviation values for participants with and without TBI across stimulus conditions Participants with TBI
Total accuracy Explicit accuracy Main character/event Background Inferential accuracy Physical inference Mental inference
Participants without TBI
Range
Mean
SD
Range
Mean
SD
51.25%-97.50% 72.50%-100% 75.00%-100% 70.00%-100% 30.00%-95.00% 30.00%-90.00% 20.00%-100%
81.08% 90.17% 91.33% 89.00% 72.00% 68.00% 76.00%
12.15 7.47 7.43 8.49 18.50 21.11 21.65
95.00%-100% 95.00%-100% 95.00%-100% 95.00%-100% 90.00%-100% 90.00%-100% 90.00%-100%
98.25% 98.17% 98.33% 98.00% 98.33% 97.33% 99.33%
1.62 2.00 2.44 2.54 3.09 4.58 2.58
Abbreviations: SD, standard deviation; TBI, traumatic brain injury.
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Use of Visual Cues by Adult With TBI and VS Domain scores (r = 0.538, P = .039; r = .603, P = .017, respectively). No significant correlations emerged between total accuracy scores and age, education, time postinjury, or WRAT-4 reading subtest achievement. Response accuracy to explicit versus inferential stimulus items Participants without TBI Participants without TBI performed at near ceiling levels for both explicit and inferential stimulus items. Paired t test computation revealed no significant difference in response accuracy scores between the 2 conditions, t14 = 0.159, P = .876. Given the consistently high accuracy scores achieved by participants without TBI and the finding of no significant accuracy difference in response to explicit versus inferential stimuli, no further analyses were performed with these data. Participants with TBI Participants with TBI achieved lower average accuracy scores than participants without TBI for both explicit and inferential stimulus conditions. Paired t test computation revealed a significant difference between explicit and inferential accuracy scores, t14 = 4.905, P = .000. Post hoc analyses allowed for further exploration of response accuracy within each stimulus condition for participants with TBI. Explicit stimulus condition
Explicit stimulus items included those requiring attention to depicted main characters/events and those requiring attention to depicted background details. Response accuracy scores for each participant with TBI appear in Figure 1. As a group, participants performed with roughly comparable accuracy given stimulus items addressing the main character/event and background
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details. Computation of a paired t test confirmed no significant difference between these stimulus items for participants with TBI, t14 = 1.606, P = .131. Computation of correlation coefficients between participants’ total explicit accuracy percentages and their EF Domain and VS Domain scores on the CLQT revealed no significant correlations (EF Domain: r = 0.394, P = .1491; VS Domain: r = 0.409, P = .1325). Inferential stimulus condition
Inferential stimuli included those requiring formation of physical and mental inferences. Physical and mental inference accuracy scores for each participant with TBI appear in Figure 2. Overall, participants with TBI achieved lower accuracy percentages in response to both kinds of inferential stimulus items than they obtained for either kind of explicit stimuli. The average percentage correct for physical inference items was lower than that for mental inference items; however, paired t test computation revealed no significant difference between physical and mental inference accuracy, t14 = 1.445, P = .171. Correlation coefficients between participants’ total inferential accuracy percentages and their CLQT EF and VS Domain scores were both significant (EF Domain: r = 0.547, P = .0334; VS Domain: r = 0.627, P = .0108). Visual inspection of response accuracy data revealed variable individual performance patterns that may have contributed to the failure to detect significant physical versus mental inference differences. Specifically, 9 of the 15 participants with TBI achieved higher performance accuracy scores on mental than physical inferences, 4 participants demonstrated the opposite pattern, and 2 participants achieved equal scores. Furthermore, the physical versus mental inference accuracy scores of 6 participants (ie, 40%) differed by 20 percentage points or more, thus suggesting high variability between inference types for a subset of the participant group.
Figure 1. Main character/event and background response accuracy scores for each participant with TBI.
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Figure 2. Physical and mental inference response accuracy scores for each participant with TBI.
DISCUSSION This study’s purpose was to investigate the accuracy with which people with and without severe TBI extract explicit (ie, main character/event or background detail) and inferential (ie, mental or physical inference) information from high-context images. As hypothesized, individuals with TBI were less accurate than individuals without TBI at extracting the desired information (RQ1). Given explicit versus inferential stimuli, individuals without TBI demonstrated comparable performance, approaching the ceiling level for both conditions. This pattern differed from that of participants with TBI who demonstrated significantly higher response accuracy given explicit information than inferential information (RQ2). Contrary to our hypotheses, participants with TBI did not demonstrate performance differences between main character/event and background stimulus items (RQ3) or between mental and physical inference stimulus items (RQ4); however, inferential processing accuracy varied for some participants with TBI based on inference type. Individual accuracy differences to physical versus mental inferences likely contributed to the lack of significant findings between stimulus conditions and, therefore, warrant future investigation. Inferential processing following TBI Researchers have previously documented that interpreting and understanding cognitive and elaborative inferences—that is, implied rather than explicitly stated communicative content4,5 —are problematic for people with TBI.4,5,13,15,25 Knowledge about this difficulty comes from examining the comprehension accuracy of people with TBI when presented with inferential and implied content through auditory, written, or visual modalities.5,26,27 Researchers have documented challenges among individuals with TBI when they interpret visually displayed, inferential information conveyed through par-
alinguistic or extralinguistic features.4,5,13 For example, Evans and Hux13 reported that individuals with TBI demonstrated the most successful interpretation of inferential information when combined verbal and visual cues were present in video-recorded interactions; however, individuals with TBI displayed poorer performance on inferential stimuli than did participants without neurological impairments. Similarly, Zupan and Neumann39 found that individuals with TBI were better at recognizing affect from multimodal film clips than from stimuli limited to a single modality. Johnson and Turkstra5 also reported problems with elaborative inferential processing by adults with TBI during naturalistic, face-to-face interactions; these individuals made significantly more elaborative inference errors than their peers without TBI despite the presence of nonverbal visual cues. All of these findings reinforce the notion that Theory of Mind deficits are prevalent among people with TBI.20,40–42 The current findings confirm the difficulties people with TBI experience when relying on visually presented information to interpret simple active sentences. Specifically, the researchers examined the interpretation of explicit and inferential information conveyed through written sentences and static, contextually rich images. Collectively, participants with TBI demonstrated poorer performance on inferential stimuli than participants without TBI. Within the group of adults with TBI, a performance discrepancy also existed between inferential and explicit items, thus suggesting a particular challenge using visual cues to interpret elaborative inferences. Given that (1) sentence stimuli did not differ in linguistic structure across conditions, (2) participants with TBI did not have aphasia, and (3) performance on the WRAT-4 reading subtest did not correlate significantly with experimental task accuracy, this discrepancy is not attributable to impaired linguistic processing of the presented information. Thus, alternate explanations warrant consideration.
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Use of Visual Cues by Adult With TBI Interpretation of findings Three potential explanations exist to account for the observed performance pattern. First, using static images may have limited access to nonverbal information, thus prompting inferior performance by people with TBI. Second, cognitive processing demands required when interpreting elaborative inferences may have exceeded the capabilities of participants with TBI. Third, participants with TBI may have had visual processing deficits affecting their integration of visual information. Static images Using static images as stimuli increased experimental control but simultaneously limited the amount of extralinguistic information provided to participants. Turkstra15 cautioned against using static images to evaluate inferential skills because the lack of movement cues typical of naturalistic conversations may result in overidentification of inferential processing deficits in adults with TBI. Consistent with this logic, using static images limiting the extent and type of available visual cues may have contributed to the observed inferior performance of participants with TBI compared with their neurologically intact peers. Still, the fact that these cues were not essential for adults without TBI to perform the experimental task accurately suggests that interpreting elaborative inferences is an area of particular challenge following acquired brain injury. Future investigations should explore the underlying source of inference interpretation deficits observed among individuals with TBI. Cognitive processing demands Previous researchers have suggested high working memory demands as contributors to challenges people with TBI experience when interpreting inferential information.3–5,26 Working memory problems after TBI are common and can contribute substantially to cognitive processing inefficiencies.43–45 Because prior investigations addressing inferential processing have included high working memory demands, this explanation for poor performance seemed plausible. However, in this study, the researchers strategically limited reliance on working memory by presenting static stimuli that remained visible for as long as desired. Despite this, participants with TBI persisted in exhibiting a significant performance gap between explicit and inferential stimuli. This suggests that working memory deficits alone inadequately explain participants’ poor performance when making judgments about elaborative inferences. The finding of a significant correlation between performance accuracy on inferential stimulus items and the CLQT EF Domain score suggests an aspect of executive dysfunction contributed to impaired inferential reason-
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ing. The EF Domain includes subtests (eg, Symbol Trails and Design Generation) dependent to varying extents on working memory and other cognitive processes. Given that the current findings suggest that working memory alone is an insufficient explanation for the observed performance, the possibility exists that other cognitive contributors to executive functioning are responsible. Specificity about the nature and extent of other cognitive limitations and their relation to interpreting visual inferential information remains unclear at this time. Visual processing following TBI Performance difficulties of individuals with TBI may relate to deficits integrating information from multiple sources or processing visual information within pictorial stimuli. The lack of significant difference between main character/event and background stimulus items suggests that participants with TBI successfully interpreted both global and detailed image content in isolation. Performance deficits, however, may have resulted from problems integrating or attending to both main character/event and background information collectively, thus resulting in unsuccessful inferential interpretation. Using eye-tracking technology could provide helpful data about eye movement patterns of adults with TBI when interpreting visual information. Understanding the viewing patterns and amount of visual processing devoted to specific image components may help researchers further understand individual performance differences. A second possibility is that the participants with TBI may have had difficulty processing some or all of the visual information included within the images. A significant correlation between inferential stimulus accuracy and the CLQT VS Domain score for participants with TBI suggests that visual-spatial processing deficits are associated with inferior inferential reasoning skills. In future studies, asking participants to explain their reasoning behind image selections may shed light on problematic aspects of visual integration and processing. Limitations The sample size of this study limits interpretation and generalization of findings. In all likelihood, the relatively small sample provided insufficient power and may have contributed to type II errors in data analysis. In particular, a larger sample may have resulted in detection of differences between physical and mental inference scores. Implications A need exists to determine how individuals with TBI perform tasks relying heavily on visual processing skills www.headtraumarehab.com
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for interpretation of inferential information. Visual stimuli are readily available in natural settings and may be static or movement based. Regardless of presentation manner, interpreting inferences associated with visual content is a frequent occurrence. Given the difficulties individuals with TBI demonstrate processing and interpreting inferential content presented visually, difficulties
gaining information from the environment may arise. To address these impairments, researchers and clinicians need information about what aspects of visual stimuli alter attention and information integration. With this, effective therapeutic techniques to enhance visual information integration and, consequently, improve content comprehension may emerge.
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mentalizing ability, and social communication. Neuropsychology. 2004;18:572–579. Havet-Thomassin V, Allain P, Etcharry-Bouyx F, Le Gall D. What about theory of mind after severe brain injury? Brain Inj. 2006;20:83–91. Hux K, ed. Assisting Survivors of Traumatic Brain Injury: The Role of speech-language Pathologists. 2nd ed. Austin, TX: Pro-Ed; 2011. Body R, Perkins MR. Validation of linguistic analyses in narrative discourse after traumatic brain injury. Brain Inj. 2004;18:707–724. Chapman SB, Culhane KA, Levin HS, et al. Narrative discourse after closed-head injury in children and adolescents. Brain Lang. 1992;43:42–65. Coelho CA, Grela B, Corso M, Gamble A, Feinn R. Microlinguistic deficits in the narrative discourse of adults with traumatic brain injury. Brain Inj. 2005;19:1139–1145. Ferstl EC, Guthke T, von Cramon DY. Text comprehension after brain injury: left prefrontal lesions affect inference processes. Neuropsychology. 2002;16:292–308. Schmitter-Edgecombe M, Bales WB. Understanding text after severe closed-head injury: assessing inferences and memory operations with a think-aloud procedure. Brain Lang. 2005;94:331–346. Sohlberg MM, Griffiths GG, Fickas S. An evaluation of reading comprehension of expository text in adults with traumatic brain injury. Am J Speech-Lang Pathol. 2014;23:160–175. Adolphs R, Tranel D, Damasio AR. Dissociable neural systems for recognizing emotions. Brain Cogn. 2003;52:61–69. Collignon O, Girard S, Gosselin F, et al. Audio-visual integration of emotion expression. Brain Res. 2008;1242:126–135. Schultz J, Pilz KS. Natural facial motion enhances cortical responses to faces. Exp Brain Res. 2009;194:465–475. Fortuny LA, Briggs M, Newcombe F, Ratcliff G, Thomas C. Measuring the duration of post traumatic amnesia. J Neurol Neurosurg Psychiatry. 1980;43:377–379. Wilkinson G, Robertson G. Wide Range Achievement Test 4 (WRAT-4). Lutz, FL: PAR, Inc; 2006. Kertesz A. Western Aphasia Battery-Revised (WAB-R). San Antonio, TX: Pearson Education; 2006. Helm-Estabrooks N. Cognitive Linguistic Quick Test. San Antonio, TX: The Psychological Corporation; 2001. Folstein MF, Folstein SE, McHugh PR. Mini-mental state: a practical method for grading the cognitive state of patient for the clinical. J Psychiatr Res. 1975;12:189–198. Wallace SE, Hux K, Brown J, Knollman-Porter K. High-context images: comprehension of main, background, and inferential information by people with aphasia. Aphasiology. 2014;28:713–730. Flesch R. A new readability yardstick. J Appl Psychol. 1948;32:221– 233. Gastwirth JL, Gel YR, Miao W. The impact of Leveness test of equality of variances on statistical theory and practice. Statist Sci. 2009;24:343–360. Zupan B, Neumann D. Affect recognition in traumatic brain injury: responses to unimodal and multimodal media. J Head Trauma Rehabil. 2014;29:E1–E12.
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Use of Visual Cues by Adult With TBI 40. McDonald S, Bornhofen C, Shum D, Long E, Saunders C, Neulinger K. Reliability and validity of The Awareness of Social Inference Test (TASIT): a clinical test of social perception. Disabil Rehabil. 2006;28:1529–1542. 41. McDonald S, Flanagan S, Rollins J, Kinch J. TASIT: a new clinical tool for assessing social perception after traumatic brain injury. J Head Trauma Rehabil. 2003;18:219–238. 42. Henry J, Phillips L, Crawford J, Ietswaart M, Summers F. Theory of mind following traumatic brain injury: The role of emotion recognition and executive dysfunction. Neuropsychologia. 2006;44:1623– 1628.
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43. Klingberg T. Training and plasticity of working memory. Trends Cogn Sci. 2010;14:317–324. 44. McAllister T, Flashman L, Sparling M, Saykin A. Working memory deficits after traumatic brain injury: catecholaminergic mechanisms and prospects for treatment-a review. Brain Inj. 2004;18:331–350. 45. Whyte E, Skidmore E, Aizenstein H, Ricker J, Butters M. Cognitive impairment in acquired brain injury: a predictor of rehabilitation outcomes and an opportunity for novel interventions. Am Acad Physical Med Rehabil. 2011;3(6): 45–51.
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Use of Visual Cues by Adults With Traumatic Brain Injuries to Interpret Explicit and Inferential Information Jessica A. Brown, PhD; Karen Hux, PhD; Kelly Knollman-Porter, PhD; Sarah E. Wallace, PhD Objective: Concomitant visual and cognitive impairments following traumatic brain injuries (TBIs) may be problematic when the visual modality serves as a primary source for receiving information. Further difficulties comprehending visual information may occur when interpretation requires processing inferential rather than explicit content. The purpose of this study was to compare the accuracy with which people with and without severe TBI interpreted information in contextually rich drawings. Participants: Fifteen adults with and 15 adults without severe TBI. Design: Repeated-measures between-groups design. Main Measures: Participants were asked to match images to sentences that either conveyed explicit (ie, main action or background) or inferential (ie, physical or mental inference) information. The researchers compared accuracy between participant groups and among stimulus conditions. Results: Participants with TBI demonstrated significantly poorer accuracy than participants without TBI extracting information from images. In addition, participants with TBI demonstrated significantly higher response accuracy when interpreting explicit rather than inferential information; however, no significant difference emerged between sentences referencing main action versus background information or sentences providing physical versus mental inference information for this participant group. Conclusions: Difficulties gaining information from visual environmental cues may arise for people with TBI given their difficulties interpreting inferential content presented through the visual modality. Key words: comprehension, high-context images, inferences, traumatic brain injury
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OMPREHENDING CONTENT EXPRESSED in communicative situations often involves combined linguistic and visual processing skills and requires interpreting inferred as well as explicit information. On a purely linguistic level, understanding explicit intent requires accurate interpretation of literal meanings associated with a speaker’s utterances. Fully comprehending communicative intent typically extends beyond literal linguistic interpretation, however, and requires understanding implied content as well as nonlinguistic visual information present during interactions.1 Thus, attending solely to linguistic content is rarely sufficient. Various researchers have labeled communicative expressions requiring processing beyond linguistic interpretation as cognitive inferences2 or elaborative
Author Affiliations: Department of Special Education and Communication Disorders, University of Nebraska-Lincoln, Lincoln, Nebraska (Dr Brown, Dr Hux); Department of Speech Pathology and Audiology, Miami University, Oxford, Ohio (Dr Knollman-Porter); and Department of Speech-Language Pathology, Duquesne University, Pittsburg, Pennsylvania (Dr Wallace). The authors declare no conflicts of interest. Corresponding Author: Jessica A. Brown, PhD, Department of Special Education and Communication Disorders, University of Nebraska-Lincoln, 350 Barkley Memorial Center, Lincoln, NE 68583 ([email protected]). DOI: 10.1097/HTR.0000000000000148
inferences.3,4 Accurate cognitive or elaborative inference interpretation depends on information integration from multiple sources including linguistic (eg, words and phrases), paralinguistic (eg, inflection, intonation, and prosody), extralinguistic (eg, gestures, facial expressions, and body position), and nonlinguistic (eg, setting or context) content.1,5 This information integration necessitates the use of substantial cognitive processing resources, attention to details, accessing world knowledge, and linking stated information to contextual cues.2–4 Cognitive processing and sensory integration deficits experienced by individuals with traumatic brain injury (TBI) are of particular concern with regard to interpreting communicative intents. A primary brain function is integrating and analyzing sensory information to determine appropriate responses. Traumatic brain injury frequently disrupts this function leaving individuals with impaired sensory perception and cognition.6 The visual system in particular is highly susceptible to damage, with greater than 50% of people with severe TBIs experiencing long-term visual-perceptual deficits directly affecting information processing.7,8 Given that the human visual system mediates 80% of perception, learning, cognition, and daily activities,9 processing information through this sensory modality is of particular importance.
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Use of Visual Cues by Adult With TBI Visual-perceptual impairments associated with TBI typically appear in conjunction with persistent cognitive challenges.6–12 Combined visual-perceptual and cognitive impairments may be particularly problematic when the visual modality serves as a primary source for receiving communicative content.13–16 Such situations occur whenever speakers convey information through gestures, facial expressions, tone of voice, or body movements. Additional communicative information comes from visual cues provided by the physical setting and context in which an interaction occurs. Deriving extralinguistic and paralinguistic information such as a communication partner’s feelings, expectations, wants, or beliefs during conversational interactions is a concept termed “Theory of Mind.” Considerable research exists about the Theory of Mind deficits people with TBI exhibit when attempting to integrate information from multiple sources to interpret communicative intents.17–20 Most individuals with severe TBIs display cognitivecommunication deficits as a chronic condition.21 Because most do not have concomitant aphasia,22–24 the expectation is that they will perform accurately and efficiently on tasks requiring literal message interpretation. However, as soon as one considers the communicative context, inferential nature of communication, and need to attend to and interpret visual cues, it is apparent that accurate message interpretation requires more than literal decoding. Confirmation of this comes from research showing that most people with cognitivecommunication deficits following severe TBI accurately derive explicit meaning from written or spoken communications but may have difficulty interpreting inferential information.4,5,15,25–27 Individuals with TBI may have particular difficulty ascertaining information from visual cues. Difficulty may arise when attempting to derive information from static images due to the lack of movement cues and the differential manner and location in which the brain processes static versus dynamic stimuli.1,15,28–30 Because static images provide less information than dynamic images, processing and interpreting depicted information may be more difficult regardless of neurological status; however, adults without neurological injuries do not exhibit difficulty extracting content from static stimuli. The same is not true for people with TBI, but, to date, researchers do not know why this distinction occurs. One possibility is that attending to and integrating information from an image background as well as from primary image content may exceed the capabilities of people with TBI. This question was the motivation for this study. CURRENT STUDY A failure to attend adequately to and integrate fully available visual content may contribute to challenges
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people with TBI experience when constructing meaning from static images. This study’s purpose was to explore this possibility by determining the accuracy with which people with and without severe TBI matched written sentences relaying either explicit or inferred information to contextually rich drawings. To differentiate processing of various image components, the researchers included 2 types of explicit stimulus sentences—ones referencing a main character or event and ones referencing background or contextual details—as well as inferential stimulus sentences requiring the integration of main and background information to ascertain mental or physical inferences. Objectives The research objectives were to evaluate whether: 1. adults with and without TBI differ in their accuracy of selecting static, contextually rich images to match written content. The researchers hypothesized that adults with TBI would achieve poorer accuracy than their peers given the attention, information processing, and visual integration difficulties present within this population; 2. adults with TBI achieve higher accuracy scores when interpreting explicit versus inferential information associated with images. The researchers hypothesized that, in accordance with previous studies, adults with TBI would achieve lower scores when interpreting inferential information despite the support of contextually rich images; 3. adults with TBI achieve higher accuracy scores when interpreting sentences conveying main character/event than background information about images. Given a potential lack of attention to detail by participants with TBI, the researchers hypothesized better performance given main character/event than background information sentences; 4. adults with TBI achieve differing accuracy scores when interpreting physical versus mental inferences associated with images. The researchers hypothesized that adults with TBI would perform poorer when interpreting mental inferences given the widespread prevalence of Theory of Mind deficits associated with brain injury. METHOD Participants Participants included 15 adults with TBI and 15 ageand education-matched control participants without neurological impairments. All participants were native American English speakers and reported no developmental language or cognitive impairments. One participant was African American, and the remaining 29 were Caucasian. www.headtraumarehab.com
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Participants passed vision and motor screenings to ensure adequate capabilities to view and select experimental stimuli. Screening procedures required participants to locate and manually touch 9, 18-point font X’s appearing in various locations on a touch screen monitor and 5 details depicted in 2 high-context images similar in size and type to those presented in experimental tasks. Participants with TBI The ages of the 12 male and 3 female participants with TBIs ranged from 21 to 53 years (M = 37.47, SD = 9.55). Participants with TBI had education levels ranging from 12 to 18 years (M = 13.80, SD = 1.93). They were between 3 and 311 months postinjury (M = 133.33, SD = 128.48) and met criteria for having sustained severe initial injuries—that is, injuries causing at least 24 hours of lost consciousness and more than 1 week of posttraumatic amnesia.31 Injury severity was determined through self-report and confirmed by a caregiver or member of each participant’s rehabilitative team. At the time of study completion, 7 participants resided at a transitional rehabilitation program, 3 resided in an assisted living facility, and 5 lived semi-independently within the community. Administration of the Wide Range Achievement Test—4 (WRAT-4)32 reading subtest confirmed that all participants with TBI could decode words at or above third grade level (range: 36-52, M = 45.20, SD = 4.51)—that is, above the level of written experimental stimuli. Administration of the Western Aphasia Battery— Revised33 Aphasia Quotient confirmed that no participant with TBI had aphasia (ie, Aphasia Quotient scores ≥93.8; M = 97.73, SD = 1.83). The researchers also administered the Executive Function (EF) and Visual Spatial (VS) Domain subtests of the Cognitive-Linguistic Quick Test (CLQT)34 to provide descriptive information about current cognitive and visual processing abilities; these subtest results did not determine study eligibility. Scores for the CLQT EF Domain ranged from 12 to 35 of 40 possible points (M = 24.07, SD = 6.55). Seven of the participants with TBI achieved CLQT EF Domain scores within normal limits (ie, more than 24 points); 4 scored within the mild severity range (ie, between 20 and 23 points), 3 scored within the moderate severity range (ie, between 16 and 19 points), and 1 displayed severe deficits (ie, less than 15 points). Scores for the VS Domain ranged from 54 to 99 of 105 possible points (M = 77.47, SD = 13.19). Seven participants scored within normal limits (ie, 82 points or more), and 8 demonstrated mild deficits (ie, between 52 and 81 points). The WRAT-4 reading subtest and the CLQT EF and VS Domain subtest scores provided a means of correlating standardized test and experimental task performances of participants with TBI. Demographic and
assessment data for each participant with TBI appear in Table 1. Participants without TBI Participants without TBIs included 13 males and 2 females with ages ranging from 20 to 59 years (M = 33.33, SD = 13.67) and education levels ranging from grades 11 to 18 (M = 14.00, SD = 2.14). T test computations confirmed no significant age or education differences between participant groups, age: t28 = 0.96, P = .345; education: t28 = 0.27, P = .790. Administration of the WRAT-4 reading subtest confirmed that all participants without TBI could read at or above the third grade level (range: 35-57, M = 48.53, SD = 6.10). T test computation confirmed no significant word decoding difference between participant groups, t28 = 1.708, P = .099. To validate that participants without TBI had normal cognitive functioning, the researchers administered the Mini Mental State Exam.35 All participants without TBI achieved scores of 28 or better on the 30-point measure (M = 29.80, SD = 0.56). Materials Study materials included digital copies of Norman Rockwell drawings (www.Saturdayeveningpost.com) and 4 types of written sentences. Details about selecting and preparing stimulus images and sentences appear in Wallace et al.36 The researchers selected colored Norman Rockwell drawings as pictorial stimuli because of the complexity and high context of the images. In total, the researchers used 133 copies of Norman Rockwell drawings as the target and foil stimuli. Of these, 121 comprised experimental stimuli, and 12 comprised practice stimuli. The researchers systematically grouped images into sets of 4 for presentation on a touch screen monitor within a 2 × 2 grid. Each stimulus set contained 1 Norman Rockwell drawing as the target image and 3 Norman Rockwell drawings as foils. The researchers systematically alternated image location within the grid so that target images appeared an equal number of times in each position. In addition, the researchers systematically selected foil images to group with each target image. Foil images met the following criteria: (1) at least 1 image contained a character (eg, boy or woman) matching the target image main character; (2) if the stimulus sentence—as described below—corresponding to a target image mentioned an object, at least 1 foil image contained a matching object; (3) if the corresponding sentence indicated a location, at least 1 foil image contained a matching location; and (4) if the corresponding stimulus sentence described an action or state of being, at least 1 foil image had a matching action or state of being.
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Use of Visual Cues by Adult With TBI TABLE 1
Demographic data and standardized testing results for participants with TBI
Age (y)
Highest level of education
Time postonset of injury (mo)
1
47
18
187
2 3 4 5 6 7
39 43 21 26 21 53
16 16 14 16 14 12
310 311 20 161 14 7
8 9 10 11 12 13 14 15
35 45 34 39 33 35 47 44
14 12 12 14 13 12 12 12
5 7 3 47 296 221 105 306
Participant
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Mechanism of injury Bicycle accident MVA MVA MVA Sports injury Sports injury Bicycle accident MVA Fall MVA Blow to head MVA MVA MVA MVA
WRAT-4 Tan Reading subtesta
CLQT Executive Functioning Domainb
CLQT Visual Spatial Domainc
49
32
99
46 50 52 41 47 43
23 23 28 35 26 21
83 78 90 93 67 83
38 43 48 44 36 50 46 45
12 16 22 28 18 30 30 17
59 54 71 80 62 88 85 70
Abbreviation: CLQT, Cognitive-Linguistic Quick Test; MVA, motor vehicle accident; WRAT-4, Wide Range Achievement Test—4. a Maximum score = 57. b Maximum score = 40. c Maximum score = 105.
The researchers paired each of 60 target images with an active sentence. Forty of the written sentences comprised the explicit stimuli and required extraction of information either about the image main character (n = 20) or a background detail (n = 20). The remaining 20 sentences comprised the inferential stimuli and required extraction of information regarding a physical (n = 10) or mental (n = 10) inference. Physical inferences reported an assumed action or location of a depicted event; mental inferences reported an assumed internal belief, emotion, feeling, or desire of depicted character(s). Stimulus sentences appeared above the 2 × 2 grid displaying the target and foil images on the touch screen monitor. The print was in 48-point white font on a black screen background. Stimulus sentences across the 4 conditions included 4 to 9 words each (M = 6.43, SD = 1.28) and did not differ significantly in number of words, F3,56 = 2.330, P = .084. The researchers computed reading grade level and ease for the target sentences using Flesch-Kincaid Readability formulas.37 Flesch Reading Ease scores ranged between 91.1 and 97.7 out of 100 possible points for each sentence condition, with an average score of 93.3 across all sentence stimuli. Reading Grade Level estimates ranged from 1.1 to 2.1, with an average of grade 1.8 across all stimuli. Computation of 2 analysis of variances confirmed no significant differences among the 4 sentence sets regarding Reading Ease, F3,56 = 1.118, P =
.350, or Reading Grade Level, F3,56 = 0.858, P = .468. Examples of sentence stimuli appear in Table 2. Procedures Participants completed all study activities within 1 session lasting less than 1 hour. The researchers first administered standardized assessments and screening measures. Once a potential participant demonstrated visual, motor control, and word decoding skills adequate for the experimental task, he or she completed practice and experimental trials. Presentation of grid displays of target and foil images and associated written sentence stimuli was controlled using Direct RT by Empirisoft (New York, NY) and presented either on a 12-inch or a 14inch touch screen monitor depending on data collection site. Practice trials appeared in the same order across participants; however, experimental trials appeared in a unique random order for each participant. Experimental task completion was self-paced and required less than 15 minutes. The researchers instructed participants they could take short breaks during the experimental task, as needed; however, no participant requested a break. Participants viewed 3 practice trials presenting written and pictorial stimuli indicative of the main character/ event condition before performing the experimental task. All participants completed practice trials with 100% accuracy, thus suggesting comprehension of the task. www.headtraumarehab.com
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JOURNAL OF HEAD TRAUMA REHABILITATION/MAY–JUNE 2016
Example stimulus for each sentence type
Experimental condition Explicit Inferential
Attention focus
Example stimulus
Main action Background Physical inference Mental inference
The man is on the roof The map is hanging on the wall The boy is running away from home The girl is hopeful about winning
The examiner provided each participant with feedback regarding practice trial performance. Following this, participants completed all 60 experimental trials. To perform the experimental task, participants first touched a “go” icon. This icon activated simultaneous presentation of the 2 × 2 grid containing 1 target and 3 foil images and the associated written stimulus sentence. Participants touched the image that best matched the written sentence to indicate selection of a response. Once a participant selected an image, the stimulus screen returned to the “go” icon. These procedures repeated until the participant had viewed and selected responses for all 60 experimental trials. No performance feedback was provided.
participant group through computation of paired t tests. To control for possible error due to multiple comparisons, the researchers applied a Bonferroni correction with an α-level of 0.01 for all between- and withingroup post hoc analyses. In addition, as appropriate, the researchers evaluated correlations between participants’ total accuracy percentages, explicit accuracy percentages, inferential accuracy percentages, CLQT EF Domain scores, CLQT VS Domain scores, and WRAT-4 reading scores to examine the contribution of specific cognitive functions to task performance. RESULTS Total response accuracy
Data analysis The researchers measured response accuracy for each experimental trial through Direct RT. Response accuracy reflected the percentage of correctly selected target images for each experimental condition. The researchers tested between-group violation of the homogeneity assumption for total response accuracy. Computation of the Levene Test of Equality of Variances38 revealed a homogeneity violation, F = 16.018, P = .000; therefore, further total response accuracy analysis involved nonparametric statistics through computation of a Mann-Whitney U test. The researchers then analyzed significant differences between explicit and inferential stimulus conditions separately for each
Table 3 displays the mean percentage correct, standard deviation, and score range for each participant group across stimulus conditions. Participants with TBI collectively achieved an average total accuracy score of 81.08% across all stimulus items (SD = 12.15). Participants without TBI achieved higher and less variable average total accuracy scores than participants with TBI (M = 98.25%, SD = 1.62). The Mann-Whitney U test computation confirmed a significant total accuracy score difference between groups, U = 5.50, P < .0001. Computation of a correlation coefficient between total accuracy scores and testing and demographic information for participants with TBI revealed a significant linear relation only between total accuracy and CLQT EF
TABLE 3 Ranges, mean response accuracy percentages, and standard deviation values for participants with and without TBI across stimulus conditions Participants with TBI
Total accuracy Explicit accuracy Main character/event Background Inferential accuracy Physical inference Mental inference
Participants without TBI
Range
Mean
SD
Range
Mean
SD
51.25%-97.50% 72.50%-100% 75.00%-100% 70.00%-100% 30.00%-95.00% 30.00%-90.00% 20.00%-100%
81.08% 90.17% 91.33% 89.00% 72.00% 68.00% 76.00%
12.15 7.47 7.43 8.49 18.50 21.11 21.65
95.00%-100% 95.00%-100% 95.00%-100% 95.00%-100% 90.00%-100% 90.00%-100% 90.00%-100%
98.25% 98.17% 98.33% 98.00% 98.33% 97.33% 99.33%
1.62 2.00 2.44 2.54 3.09 4.58 2.58
Abbreviations: SD, standard deviation; TBI, traumatic brain injury.
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Use of Visual Cues by Adult With TBI and VS Domain scores (r = 0.538, P = .039; r = .603, P = .017, respectively). No significant correlations emerged between total accuracy scores and age, education, time postinjury, or WRAT-4 reading subtest achievement. Response accuracy to explicit versus inferential stimulus items Participants without TBI Participants without TBI performed at near ceiling levels for both explicit and inferential stimulus items. Paired t test computation revealed no significant difference in response accuracy scores between the 2 conditions, t14 = 0.159, P = .876. Given the consistently high accuracy scores achieved by participants without TBI and the finding of no significant accuracy difference in response to explicit versus inferential stimuli, no further analyses were performed with these data. Participants with TBI Participants with TBI achieved lower average accuracy scores than participants without TBI for both explicit and inferential stimulus conditions. Paired t test computation revealed a significant difference between explicit and inferential accuracy scores, t14 = 4.905, P = .000. Post hoc analyses allowed for further exploration of response accuracy within each stimulus condition for participants with TBI. Explicit stimulus condition
Explicit stimulus items included those requiring attention to depicted main characters/events and those requiring attention to depicted background details. Response accuracy scores for each participant with TBI appear in Figure 1. As a group, participants performed with roughly comparable accuracy given stimulus items addressing the main character/event and background
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details. Computation of a paired t test confirmed no significant difference between these stimulus items for participants with TBI, t14 = 1.606, P = .131. Computation of correlation coefficients between participants’ total explicit accuracy percentages and their EF Domain and VS Domain scores on the CLQT revealed no significant correlations (EF Domain: r = 0.394, P = .1491; VS Domain: r = 0.409, P = .1325). Inferential stimulus condition
Inferential stimuli included those requiring formation of physical and mental inferences. Physical and mental inference accuracy scores for each participant with TBI appear in Figure 2. Overall, participants with TBI achieved lower accuracy percentages in response to both kinds of inferential stimulus items than they obtained for either kind of explicit stimuli. The average percentage correct for physical inference items was lower than that for mental inference items; however, paired t test computation revealed no significant difference between physical and mental inference accuracy, t14 = 1.445, P = .171. Correlation coefficients between participants’ total inferential accuracy percentages and their CLQT EF and VS Domain scores were both significant (EF Domain: r = 0.547, P = .0334; VS Domain: r = 0.627, P = .0108). Visual inspection of response accuracy data revealed variable individual performance patterns that may have contributed to the failure to detect significant physical versus mental inference differences. Specifically, 9 of the 15 participants with TBI achieved higher performance accuracy scores on mental than physical inferences, 4 participants demonstrated the opposite pattern, and 2 participants achieved equal scores. Furthermore, the physical versus mental inference accuracy scores of 6 participants (ie, 40%) differed by 20 percentage points or more, thus suggesting high variability between inference types for a subset of the participant group.
Figure 1. Main character/event and background response accuracy scores for each participant with TBI.
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Figure 2. Physical and mental inference response accuracy scores for each participant with TBI.
DISCUSSION This study’s purpose was to investigate the accuracy with which people with and without severe TBI extract explicit (ie, main character/event or background detail) and inferential (ie, mental or physical inference) information from high-context images. As hypothesized, individuals with TBI were less accurate than individuals without TBI at extracting the desired information (RQ1). Given explicit versus inferential stimuli, individuals without TBI demonstrated comparable performance, approaching the ceiling level for both conditions. This pattern differed from that of participants with TBI who demonstrated significantly higher response accuracy given explicit information than inferential information (RQ2). Contrary to our hypotheses, participants with TBI did not demonstrate performance differences between main character/event and background stimulus items (RQ3) or between mental and physical inference stimulus items (RQ4); however, inferential processing accuracy varied for some participants with TBI based on inference type. Individual accuracy differences to physical versus mental inferences likely contributed to the lack of significant findings between stimulus conditions and, therefore, warrant future investigation. Inferential processing following TBI Researchers have previously documented that interpreting and understanding cognitive and elaborative inferences—that is, implied rather than explicitly stated communicative content4,5 —are problematic for people with TBI.4,5,13,15,25 Knowledge about this difficulty comes from examining the comprehension accuracy of people with TBI when presented with inferential and implied content through auditory, written, or visual modalities.5,26,27 Researchers have documented challenges among individuals with TBI when they interpret visually displayed, inferential information conveyed through par-
alinguistic or extralinguistic features.4,5,13 For example, Evans and Hux13 reported that individuals with TBI demonstrated the most successful interpretation of inferential information when combined verbal and visual cues were present in video-recorded interactions; however, individuals with TBI displayed poorer performance on inferential stimuli than did participants without neurological impairments. Similarly, Zupan and Neumann39 found that individuals with TBI were better at recognizing affect from multimodal film clips than from stimuli limited to a single modality. Johnson and Turkstra5 also reported problems with elaborative inferential processing by adults with TBI during naturalistic, face-to-face interactions; these individuals made significantly more elaborative inference errors than their peers without TBI despite the presence of nonverbal visual cues. All of these findings reinforce the notion that Theory of Mind deficits are prevalent among people with TBI.20,40–42 The current findings confirm the difficulties people with TBI experience when relying on visually presented information to interpret simple active sentences. Specifically, the researchers examined the interpretation of explicit and inferential information conveyed through written sentences and static, contextually rich images. Collectively, participants with TBI demonstrated poorer performance on inferential stimuli than participants without TBI. Within the group of adults with TBI, a performance discrepancy also existed between inferential and explicit items, thus suggesting a particular challenge using visual cues to interpret elaborative inferences. Given that (1) sentence stimuli did not differ in linguistic structure across conditions, (2) participants with TBI did not have aphasia, and (3) performance on the WRAT-4 reading subtest did not correlate significantly with experimental task accuracy, this discrepancy is not attributable to impaired linguistic processing of the presented information. Thus, alternate explanations warrant consideration.
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Use of Visual Cues by Adult With TBI Interpretation of findings Three potential explanations exist to account for the observed performance pattern. First, using static images may have limited access to nonverbal information, thus prompting inferior performance by people with TBI. Second, cognitive processing demands required when interpreting elaborative inferences may have exceeded the capabilities of participants with TBI. Third, participants with TBI may have had visual processing deficits affecting their integration of visual information. Static images Using static images as stimuli increased experimental control but simultaneously limited the amount of extralinguistic information provided to participants. Turkstra15 cautioned against using static images to evaluate inferential skills because the lack of movement cues typical of naturalistic conversations may result in overidentification of inferential processing deficits in adults with TBI. Consistent with this logic, using static images limiting the extent and type of available visual cues may have contributed to the observed inferior performance of participants with TBI compared with their neurologically intact peers. Still, the fact that these cues were not essential for adults without TBI to perform the experimental task accurately suggests that interpreting elaborative inferences is an area of particular challenge following acquired brain injury. Future investigations should explore the underlying source of inference interpretation deficits observed among individuals with TBI. Cognitive processing demands Previous researchers have suggested high working memory demands as contributors to challenges people with TBI experience when interpreting inferential information.3–5,26 Working memory problems after TBI are common and can contribute substantially to cognitive processing inefficiencies.43–45 Because prior investigations addressing inferential processing have included high working memory demands, this explanation for poor performance seemed plausible. However, in this study, the researchers strategically limited reliance on working memory by presenting static stimuli that remained visible for as long as desired. Despite this, participants with TBI persisted in exhibiting a significant performance gap between explicit and inferential stimuli. This suggests that working memory deficits alone inadequately explain participants’ poor performance when making judgments about elaborative inferences. The finding of a significant correlation between performance accuracy on inferential stimulus items and the CLQT EF Domain score suggests an aspect of executive dysfunction contributed to impaired inferential reason-
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ing. The EF Domain includes subtests (eg, Symbol Trails and Design Generation) dependent to varying extents on working memory and other cognitive processes. Given that the current findings suggest that working memory alone is an insufficient explanation for the observed performance, the possibility exists that other cognitive contributors to executive functioning are responsible. Specificity about the nature and extent of other cognitive limitations and their relation to interpreting visual inferential information remains unclear at this time. Visual processing following TBI Performance difficulties of individuals with TBI may relate to deficits integrating information from multiple sources or processing visual information within pictorial stimuli. The lack of significant difference between main character/event and background stimulus items suggests that participants with TBI successfully interpreted both global and detailed image content in isolation. Performance deficits, however, may have resulted from problems integrating or attending to both main character/event and background information collectively, thus resulting in unsuccessful inferential interpretation. Using eye-tracking technology could provide helpful data about eye movement patterns of adults with TBI when interpreting visual information. Understanding the viewing patterns and amount of visual processing devoted to specific image components may help researchers further understand individual performance differences. A second possibility is that the participants with TBI may have had difficulty processing some or all of the visual information included within the images. A significant correlation between inferential stimulus accuracy and the CLQT VS Domain score for participants with TBI suggests that visual-spatial processing deficits are associated with inferior inferential reasoning skills. In future studies, asking participants to explain their reasoning behind image selections may shed light on problematic aspects of visual integration and processing. Limitations The sample size of this study limits interpretation and generalization of findings. In all likelihood, the relatively small sample provided insufficient power and may have contributed to type II errors in data analysis. In particular, a larger sample may have resulted in detection of differences between physical and mental inference scores. Implications A need exists to determine how individuals with TBI perform tasks relying heavily on visual processing skills www.headtraumarehab.com
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for interpretation of inferential information. Visual stimuli are readily available in natural settings and may be static or movement based. Regardless of presentation manner, interpreting inferences associated with visual content is a frequent occurrence. Given the difficulties individuals with TBI demonstrate processing and interpreting inferential content presented visually, difficulties
gaining information from the environment may arise. To address these impairments, researchers and clinicians need information about what aspects of visual stimuli alter attention and information integration. With this, effective therapeutic techniques to enhance visual information integration and, consequently, improve content comprehension may emerge.
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