BRAIN

AND

LANGUAGE

42, 203-217 (1992)

Sensitivity to Conversational Deviance in Right-HemisphereDamaged Patients ALEXANDRA REHAK Aphasia Research Center, Department of Neurology, Boston University and Harvard Project Zero

JOAN University

School of Medicine,

A. KAPLAN

of California

at Berkeley

AND HOWARD GARDNER Aphasia Research Center, Department of Neurology, Boston University Medical Center, Boston Veterans Administration Medical Center, and Harvard Project Zero

To participate meaningfully in conversation, speakers must be sensitive to statements which advance and those which block the direction of a discourse. The effect of right-hemisphere damage (RHD) on sensitivity to conversational advancers and blockers was investigated by asking subjects to interpret normal conversations and conversations which were blocked by violations of Gricean maxims: specifically, tangential and redundant statements. Results indicate that RHD patients function normally in canonical, directed conversation. However, they have difficulty interpreting and judging the effect of blocking statements, particularly with regard to tangentiality. The results are discussed in terms of a mental model of directed conversation which incorporates both structural and affective components. 0 1992 Academic Press, Inc.

Conversation is perhaps the most important and most natural form of human communication. The work of Grice (1975) is particularly useful Address correspondence and reprint requests to Howard Gardner, Harvard Project Zero, Longfellow Hall, Cambridge, MA 02138. The research reported in this paper was supported by NIH Grants 5POl DC00081 and 5ROl DCO0102, by the Research Service of the Veterans Administration, and by Harvard Project Zero. We are grateful to Nancy Lefkowitz, Director, Speech and Language Pathology and her colleagues at the Spaulding Rehabilitation Hospital. 203 0093-934X/92 $3.00 Copyright Q 1992 by Academic Press, Inc. All rights of reproduction in any form reserved.

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in conceptualizing conversational structure and conventions. Grice theorized that participants in a conversation cooperate with each other by following four “maxims”: (1) they provide an appropriate quantity of information; (2) they provide information of quality, i.e., information which is true; (3) their statements are in clear relation (i.e., relevant) to the conversation or situation; and (4) they present information in a clear and orderly manner. When a speaker utters a statement which is a clear violation of one of the maxims (thereby “flouting” a maxim), it acts as a trigger for the listener. Rather than assuming that the speaker is being uncooperative, the listener uses her world knowledge, knowledge of linguistic and conversational conventions, and knowledge of the speaker to interpret the violation as meaning something more or something other than what is actually said (Murphy, 1990). For example, saying “You’re a fine friend!” to someone who has just done something nasty, violates the maxim of quality, but the listener can use her knowledge of the situation and of the pragmatic rules of sarcasm to make sense of the remark. Taking a cognitive perspective, we propose that people have a mental model (Johnson-Laird, 1983) of directed conversation which incorporates principles such as Grice’s. Such a model provides a map of a “normal” conversation in which one or more of the participants has a particular goal (e.g., a specific topic they wish to discuss). The model includes knowledge of “volleys” which move a conversation in the desired direction. Some types of statements act as advancers because they move the conversation toward a cooperatively reached goal or topic. Statements which conform to Grice’s maxims, or violations of the maxims which can be interpreted as cooperative, fall into this category. Other statements are blockers which one participant uses to turn the conversation away from another participant’s goal. Violations of Gricean maxims which cannot be interpreted as cooperative belong in this category. When a participant blocks the direction of the conversation, the other participants must find a way to make a “repair” in order to advance the conversation. In addition to these structural aspects of conversation, the model of conversation involves an intentional/affective component. First, a conversant must be able to judge the intentions which lie behind other conversants’ advancing and blocking moves. A speaker who drops hints about something is signaling that she wants others to ask about it; the other conversants can only advance the conversation by guessing her motives and speaking accordingly. Second, successful conversants must be able to gauge the emotional impact of conversational moves on other participants in the conversation. For example, a conversant is likely to become annoyed if others block a conversation which she is trying to direct toward a specific goal. A number of indices suggest that patients with right-hemisphere damage

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(RHD) have difficulty apprehending and carrying out conversations; we propose that this difficulty may arise from deficits related to mental models of conversation. While not normally displaying the dramatic linguistic deficits associated with left-hemisphere damage, these patients exhibit more subtle language-related problems. In addition to clinical documentation of discourse comprehension deficits (see Gardner, 1975; Gardner, Brownell, Wapner, & Michelow, 1983; Joanette, Ska, Goulet, & Nespoulous, 1986; Lezak, 1983; Wechsler, 1973; Weinstein and Kahn, 1955), empirical studies have found deficits in two somewhat interdependent areas: (1) understanding language used in a noncanonical manner; and (2) integrating varied information in order to interpret discourse materials appropriately. With regard to the first category, investigators have found that RHD patients have trouble interpreting indirect requests (Foldi, 1987; Hirst, LeDoux, & Stein, 1984; Weylman, Brownell, Roman, & Gardner, 1989), understanding jokes (Bihrle, Brownell, Powelson, & Gardner, 1986; Brownell and Gardner, 1988), and interpreting nonliteral language such as metaphor, irony, and sarcasm (e.g., Kaplan, Brownell, Jacobs, & Gardner, 1990; see Ostrove, Kaplan, Brownell, and Gardner, 1990 for a review). In the second category, these patients have difficulty with holistic, context-dependent tasks such as deriving the main point or theme of a dialogue or narrative (e.g., Gardner et al., 1983; Hough, 1990) and drawing inferences in stories (Brownell, Potter, Bihrle, & Gardner, 1986). RHD discourse production has not been systematically examined by researchers. Clinicians have noted that RHD patients are often tangential and seem inappropriately positive or unconcerned about serious situations; they also may be inappropriate both in their manner of addressing others and in the conversational topics which they bring up (Gardner, 1975; Geschwind, 1976; Heilman, Bowers, & Valenstein, 1985; Lezak, 1983; Weinstein & Kahn, 1955). Repetitive or redundant conversation has not been reported. A number of nonstructural features of language may contribute to RHD patients’ problems with conversation. Often noted has been the tendency of such patients to be unconcerned and to interpret statements and behavior in the most positive light (Davidson, 1984; Sackheim, Greenberg, Weiman, Gur, Hungerbuhler, & Geschwind, 1982). RHD has also been associated with lowered sensitivity both to speech prosody and to affective information in general (cf. Heilman et al., 1985; Ross, 1981; Wechsler, 1973). There are three more general kinds of explanations of RHD deficits which have been put forward by researchers. A generalized “integration deficit” is one possible explanation for RHD patients’ difficulties with discourse (Molloy, Brownell, & Gardner, 1990). Another possibility is that RHD may result in a primary difficulty with handling the pragmatics

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of language (cf. Weylman, Brownell, and Gardner, 1988). A third theory suggeststhat RHD patients are overly acquiescent (Davidson, 1984; Sackheim et al., 1982); they may be likely to accept deviations in discourse structure and content without challenging them. While one or more of these explanations may prove to be an accurate characterization of RHD, they are too broad to be of much use in describing specific deficits related to conversation. Our proposed mental model of conversation is an attempt to specify the mental steps involved in conversing, with the aim of pinpointing those aspects of discourse processing which are affected by RHD. We hypothesized that RHD patients might suffer from a breakdown in one or more aspects of their conversational models. Specifically, RHD patients may have difficulty interpreting and/or responding to advancers and blockers in conversation. Returning to the Gricean maxims as an example, RHD patients may not be sensitive to the fact that a cooperative participant in a directed conversation will only violate a maxim as a means of advancing the conversation. This insensitivity could account for their confusion with respect to direct requests (which violate the maxim of manner) and sarcasm. These patients may not be able to recognize such violations or may be unable to divine the motivation behind them. They may also have trouble making appropriate use of advancers and blockers in their own contributions to discourse. For example, the tangential statements noted by clinicians could result from RHD patients’ being unaware that such statements function as conversational blockers: they are not clearly motivated by the situational context or by the cooperative goal of the conversation. To investigate this set of issues, we designed a series of short conversations which ended with blocking statements. The goal was to see whether normal subjects and RHD patients considered the blocking statements to be noncooperative contributions to the conversations. In each conversation, one of the speakers hinted strongly that s/he wished to discuss a certain topic. The other speaker would either advance the conversation by asking about the hint (control condition) or block it with a statement which ignored the hint. Two types of blockers based on violations of Gricean maxims were used: (1) tangential statements, which changed the subject with no transition; and (2) redundant statements, which paraphrased something said earlier in the conversation. The former type blocks the conversation by arbitrarily directing it away from the clear goal of one speaker, thus violating the maxim of relation; the latter by not introducing new and relevant information, thus violating the maxim of quantity. We chose to concentrate on these two contrasting violations in order to determine whether RHD patients are more sensitive to errors they themselves produce (i.e., tangential statements) than to ones which do not characterize

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TABLE 1 PATIENTINFORMATION Patient JM KE MM AM CB FK DK KM GL RC EW DR

Age

Education time

Postonset

Lesion site

63 58 50 71 57 64 71 69 59 4.5 74

14 years 19 years 12 years 12 years 16 years 10 years 20 years 9 years 13 years 18 years 12 years

4 months 8 months 6 months 2 years, 9 months 4 years, 10 months 2 years, 10 months 3 years, 6 months 7 years, 2 months 9 years, 7 months 5 years, 8 months 1 year, 9 months

Parietal infarct Temporoparietal infarct Occipital-parietal infarct No CT information No CT information Middle cerebral artery infarct Middle cerebral artery infarct No CT information Temporoparietal infarct Middle cerebral artery infarct Inferior temporo parietal infarct with occipital involvement No CT information.

71

12 years

8 months

their own conversation (redundant statement). We chose positive topics for half of the conversations and negative topics for the other half, in order to see whether RHD patients and normal control subjects react differently to subjects with different affective valence. We asked subjects to judge (1) the unusualness of the conversation; (2) the intention of the speaker who made the blocking statement; and (3) the effect the blocker would have on the listener. The first question was intended to test sensitivity to the blockers; the second to test ability to interpret the motivation behind them; and the third to test awareness of their inappropriateness in a directed conversation. A final question asked subjects to choose a continuation for the conversation. This measure was designed to determine whether subjects would try to “repair” the blocker by returning the conversation to the original topic (the hint). METHOD Subjects. Twelve right-handed unilaterally brain-damaged stroke patients (mean age = 63) constituted the experimental group. The subjects included patients and former patients from the Neurology Service of the Boston Veteran’s Administration Medical Center and from two private rehabilitation hospitals. Patients were excluded from the study if they had histories of prior neurological disease, psychiatric illness, head injury, or alcohol or drug abuse. Patients had an average of 14 years of education. Lesion localization was based on neurological examination, including evidence of motor and sensory deficits, as well as on CT scan information. All patients were tested at least 2 months postonset; average time postonset was 3 years, 4 months. Of the patients for whom complete CT scan information was available, one had a right anterior lesion, five had right posterior lesions, and two had lesions that were both anterior and posterior. (See Table 1 for specific subject information.) Twelve non-brain-damaged control subjects of comparable ages (mean age = 65) con-

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stituted the control group. These subjects were drawn from the same general population as the patients and had no known history of neurological or psychiatric disorder or substance abuse. This group also averaged 14 years of education. All control subjects but one were right-handed. Each subject group consisted of 10 men and 2 women. All subjects were paid for their participation. Because of the linguistically complex nature of the stimuli and experimental questions, it was not possible to use left-hemisphere-damaged patients as a control group. In this report we instead emphasize the particular pattern of results obtained from our right-hemisphere brain-damaged group and its deviation from the pattern obtained with normal controls. Stimuli. Subjects heard 12 tape-recorded, scripted conversations between two people. Each conversation consisted of two volleys between one male and one female speaker. There were three types of conversations: tangential, redundant, and control. Four conversations were devised for each of these conditions. Each conversation followed the same pattern for the first three contributions (see the Appendix): Speaker 1: Opens conversation, hints at another, more interesting topic; Speaker 2: Responds to explicit conversation opening; Speaker 1: Responds to Speaker 2, again hints at second topic. The last line varied according to the type of conversation: Tangential: Speaker 2 brings up a new, secondary topic without responding to Speaker l’s last comment or mentioning the hint (t-blocker); Redundant: Speaker 2 paraphrases something said earlier in the conversation without responding to Speaker l’s last comment or mentioning the hint (r-blocker); Control: Speaker 2 says s/he would like to hear more about the hinted-at topic (advancer). After subjects heard a conversation and answered questions about it, we asked them to select an appropriate continuation for it. We wrote three possible rejoinders for Speaker 1 to offer at the end of each conversation. For the two types of blocked conversations, Speaker 1 could: (1) repair the blocker by acknowledging the blocking statement and then returning to the hinted-at topic; (2) return to the hinted-at topic without acknowledging the blocker; (3) follow the blocker by acknowledging the blocking statement without returning to the hinted-at topic. For the advancer (control) conversations, Speaker 1 could: (1) advance the conversation further by elaborating on the hint; (2) block the conversation by repeating the hint without adding new information; (3) block the conversation by talking about a minor point mentioned earlier without mentioning the hint. Half of the conversations were on positive topics, such as the upcoming marriage of one of the speakers, and half were on negative topics, such as an accident befalling one speaker’s mother. Conversations were counterbalanced across conditions for gender of Speaker 1 and Speaker 2 as well as for affective tone of the topic. Pilot testing with a group of four college-aged adults confirmed that normal subjects could clearly perceive both the hints and the blockers in the conversations and were able to interpret them satisfactorily. Conversations were recorded using a microphone and a simple tape recorder. The same male and female speakers read each conversation; prosody was kept to a minimum so as not to provide normal control subjects with an unfair advantage over RHD patients. Procedure. Normal subjects heard all 12 conversations in a single session, which lasted from 1 to 1% hr; they heard a practice conversation at the beginning of the session. RHD

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subjects were tested over two sessions of approximately 45 min each and heard 6 conversations in each session; they heard the same practice conversation before each session. Subjects were told that they would hear short fragments of conversations between two people and that they would be asked for their interpretations. They were also told that after answering some questions about a conversation, they would be asked to choose the best ending to the conversation from a set of three alternatives. The conversations were played on a portable tape recorder. All subjects were provided with scripts of the conversation, of the two multiple-choice questions, and of the three continuations (once they had answered the questions). These scripts minimized prosodic factors and excessive demands on memory as possible confounding problems. After each conversation was played, subjects were asked the following four questions: General Comprehension: What would you say the main topic of the conversation is? Sensitivity to Blocker: Did the conversation sound normal to you, or did something about it strike you as odd? Interpretation of Motivation for Blocker: From the last thing [Speaker 21 said, do you think s/he wanted to: (A) continue talking about the same topic; (B) repeat or confirm something [Speaker l] said earlier; (C) change the topic. [Note: the three responses to this question were designed to correspond to the three types of final blocking advancing statements; we considered A to be the most plausible interpretation for the advancer in the control conversations, B for the blocker in the redundant conversations, and C for the blocker in the tangential conversations.] Interpretation of Blocker’s Effect on Speaker 1: When [Speaker 21 said that, do you think that it: A) had no real effect on [Speaker 11; B) made [Speaker l] feel happy or relieved; C) made [Speaker 11 feel hurt or angry. Why? [Note: We considered that B would be the most appropriate interpretation for the control conversations, while C would be appropriate for the two blocked conversations.] After answering these questions, subjects were instructed to read over the conversation script; they then heard the following question: Ability to Repair Blocker Advance Conversation: What would be the best thing for [Speaker l] to say next? The experimenter then played the three possible continuations for the subject, who was again given a script. Subjects were told they could refer back to the script of the earlier part of the conversation if they wished. Subjects were asked to justify their answers.

RESULTS Overview. The results reveal that RHD patients performed in a manner similar to that of normal subjects on the control conversations, showed some occasional difficulty in interpreting the redundant conversations, and had considerable difficulty with the tangential conversation. The factor of affect proved to have little effect on either subject group, and thus is not discussed below.

[Note: Unless otherwise indicated, analyses were two-way, mixed design analyses of variance (ANOVAs) which examined one of the three types of conversations using Subject Group and Affect as the two factors.]

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General comprehension. This question was designed solely to determine whether subjects had been paying adequate attention to the conversation. Subjects were considered to have followed the conversation adequately if they mentioned the main topic, since it was referred to in at least three of the four contributions to each conversation. There were only two instances of subjects missing this question (both were RHD patients). Sensitivity to blocker. We analyzed how often subjects judged conversations to be “normal.” Because of the subjective nature of conversation, we felt it would be more natural and informative to have subjects give free responses rather than simply label each conversation “normal” or “abnormal.” Responses were then categorized as indicating whether the subject thought the conversation “normal” or “abnormal” by two independent raters. The raters were not informed which responses came from RHD patients; they agreed on 90% of the responses. Analyses revealed that RHD patients judged both types of blocked conversations as normal significantly more often than did control subjects (Tangential Group: F(1, 22) = 10.70; p < 305; Redundant Group: F(1, 22) = 19.71; p < .OOOS).The RHD patients were less likely to judge control conversations as normal; the control subjects reached ceiling on this measure, but the significant difference was confirmed by a x2 test (p < .05). In addition, a larger, three-way mixed-design ANOVA of all responses (Conversation Type x Group x Affect) showed that all subjects were more likely to judge the blocked conversations as abnormal than the control ones (Conversation Type: F(2, 44) = 46.08; p < .OOOl). Interpretation of motivation for blocker. We analyzed the number of times subjects chose the most plausible interpretation of Speaker 2’s final blocking or advancing statement (see Procedure). Control subjects were more likely than RHD subjects to choose the most plausible interpretation of the tangential blockers, which was that the speaker wanted to change the subject (Group, F(1, 22) =. 8.05; p < .Ol). There was no significant difference between the two groups for the redundant blocked conversations (the plausible interpretation was that the speaker wanted to repeat or confirm something) or the control conversations (the plausible interpretation was that the speaker wanted to keep talking about the same topic). In order to examine the types of errors subjects made when they did not choose the most plausible interpretation, we performed two two-day mixed design ANOVAs (Group X Error Type) on the number of times alternative interpretations were selected for each of the two blockers (note that there were two alternative interpretations for each type of conversation). For the tangential conversations, RHD patients were significantly more likely than controls to interpret the blocker as meaning that the speaker wanted to “continue talking about the same topic”; neither group

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was likely to choose the interpretation “repeat or confirm something that was said earlier” (Group x Error Type interaction, F(1, 22) = 4.85; p < .OS). For the redundant conversations, both groups were more likely to choose “continue talking about the same topic” than “change the topic” as the motivation for the blocker (Error Type, F(1, 22) = 6.81; p < .025); in addition, RHD patients were more likely overall to choose one of these alternative interpretations (Group, F(1, 22) = 5.01; p < .05). Interpretation of blocker’s effect on speaker 1. We analyzed the number of times subjects chose what we considered to be the appropriate interpretation of the blocker or advancer’s effect on the speaker who heard it (see Procedure). For the tangential conversations, RHD patients were significantly less likely than control patients to say that the blocker made Speaker 1 feel hurt or angry (Group, F(1, 22) = 15.80; p < .OOl). No difference between the groups was noted for the redundant and control conversations. Examining only the two types of blocked conversations, we analyzed the number of times subjects made what we considered to be inappropriate judgments of the affective effect of the blocker with two three-way mixed design ANOVAs (Group x Conversation Type x Affect) on the two types of errors: “had no effect on Speaker 1” and “made Speaker 1 feel happy or relieved.” RHD patients were more likely than controls to say that the tangential blockers “had no effect on Speaker 1”; there was no group difference for the redundant blockers (Group x Conversation Type, F(1, 22) = 7.41; p < .025). No group differences were found for the “happy or relieved” error type, but all subjects were more likely to make this judgment for the redundant blockers than for the tangential ones (Conversation Type, F(1, 22) = 26.5; p < .OOOl). Ability to repair blocker advance conversation. We analyzed the number of times subjects chose the most appropriate continuation for a conversation: for the blocked conversations, this would repair the blocker; for the control conversation, it would elaborate on the hint. The analysis of the control conversations revealed no significant group differences. A three-way mixed design ANOVA (Group x Conversation Type x Affect) was performed on the two blocked conversations. RHD patients were significantly less likely than controls to select an appropriate “repair” continuation for both types of blocked conversations (Group, F(1, 22) = 7.86; p < .025).

In order to gain more information on which continuation subjects chose when they chose not to “repair” the blocked conversations, we performed two three-way mixed design ANOVAs on the number of times subjects selected each of the alternative continuations (“return to hint” and “follow blocking statement” (Group x Conversation Type x Affect). RHD patients were significantly more likely than controls to choose continuations which followed the blocking statement but ignored the hint; this was true

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for both types of blocked conversations (Group, F(1, 22) = 6.67; p < .025). No effects related to the “return to hint” continuation were found; subjects rarely chose this type of continuation. DISCUSSION The results suggest that some aspects of mental models of directed conversation are preserved subsequent to right-hemisphere damage. First, RHD patients performed similarly to normal subjects in interpreting the control conversations. They had no difficulty interpreting the “advancing” intention of the speaker who asked about the hint at the end of the conversation and, like the control subjects, judged that this “volley” would make the hinter happy. They also were able to select appropriate continuations for the control conversations. The RHD subjects differed from controls only in their assessmentof the unusualness of these conversations; they were slightly more likely than normals to judge these control conversations as unusual. However, like the control subjects, they were significantly more likely to judge these conversations as normal than the blocked ones. Thus, it appears that RHD does not strongly affect these patients’ ability to deal with canonical, cooperative, directed conversations. A somewhat different picture emerges when we examine the blocked conversations. Looking first at the redundant conversations, RHD patients performed in a manner similar to that of normals in attributing a motive to the blocker and in judging its effect on the other speaker. Thus, it is clear that they understand the conversational purpose of this type of blocker as well as normal subjects. They also are aware, at least to the same degree as normal subjects, that it is not a cooperative move. However, the RHD subjects were more likely than normal controls to say that the redundant conversations sounded normal (although, as noted, they did judge them as more abnormal than control conversations). They also were less likely than normals to try to “repair” the redundant block by bringing the conversation back to the hint; they were more likely to continue the conversation by “following” the redundant remark. It is possible that these patients do not perceive redundancy as a serious structural offense and thus do not always mark it as abnormal or attempt to “repair” it. However, they are aware of its purpose and of its emotional impact on a conversant who has a different agenda in mind. Their mental model has perhaps become more forgiving of such deviations, while still allowing the patients to arrive at correct interpretations. It should be noted that the redundant conversations posed interpretive difficulties for normal subjects as well as for the RHD patients. Both subject groups presented much clearer patterns for the other two types of conversations. There was a strong tendency (much stronger for the RHD patients) to say that redundant statements meant that the speaker

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wanted to continue talking about the same topic as opposed to the motive we considered most appropriate, “repeat or confirm something said earlier.” Likewise, both subject groups were fairly evenly split among the three possible judgments of the effect of redundancy on the hinter. Redundancy may simply not be as clear an offense as tangentiality, causing all subjects to equivocate in their judgments. The tangential conversations proved more problematic for the RHD patients. RHD subjects were more likely than normals to judge these conversations as normal and were more likely to misinterpret the motivation of the speaker, often saying that s/he wanted to continue talking about the same topic. They were less likely than normals to say that the blocker made the hinter angry, preferring to say that it had no effect. They also were more likely to continue these conversations by following the blocker’s lead rather than by steering the conversation back to the hint, just as with the redundant conversations. Thus, the RHD patients’ mental models of directed conversation seem to fall down when presented with this type of blocker to a greater extent than they do for the redundant blockers. This alternation of the threshold of acceptability may relate to their own tangential contributions to conversations. There are several possible interpretations of the results. First, there is little evidence that RHD patients suffer from an overall integration problem. If this were the case, we would expect them to answer randomly and to demonstrate problems across-the-board; instead, they performed normally on the control conversations and relatively adequately on the redundant conversations. Furthermore, in the instances when their answers did not correspond to controls’ responses, they did fall into distinct patterns of errors, indicating a difference in processing or judgment rather than a complete breakdown. It is also possible that a response bias could account for the RHD patients’ adequate performance on the control condition. For example, the RHD patients might simply have judged all conversations as normal because of a bias, leading to the differences between them and the control subjects on the blocked conversations. However, since both normal subjects and RHD patients were more likely to judge the blocked conversations as abnormal than the control conversations, it seems that the patients were at least somewhat aware of the distinction between the two. Given the different RHD performance patterns which emerged in analyzing the two different types of blocked conversations, it would be difficult to argue that they simply accepted all deviations and interpreted them as cooperative. Overall, RHD patients may suffer from a breakdown in those components of their mental models which deal with judging intention and appropriateness in conversation. Their reluctance to judge blocked conversations as unusual indicates either a failure to appreciate the inappro-

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priateness of avoiding a topic that someone wants to discuss or a failure to appreciate the intention of the hinter and/or the blocker. The fact that RHD patients preferred to continue the conversations by “following” the blocking statement while completely ignoring the hint also indicates that they may not appreciate the uncooperative nature of the blocking statement or the intention of the hinter. In sum, it appears that RHD patients are more accepting of deviations from conversational norms. Whether this is due to a general bias toward acquiescence or an inability to judge speaker intentions cannot be determined in the present instance. The clear differentiation which normal control subjects made between the advancer and blocked conversations supports our notion of a mental model of directed conversation; it may also be seen as supporting the neuropsychological reality of Grice’s maxims of relation and, to a lesser degree, quantity. Further investigation is needed to tease apart the roles played by sensitivity to intention and acquiescence in RHD conversational discourse. APPENDIX: SAMPLE CONVERSATIONS Control Ending (hint k in boldface type)

Scene: Beth and Dan meet coming out of the subway one morning. BETH-Dan, guesswhat happened yesterday. My boss told me I’m being promoted to supervisor down at the plant. Not only that, but he gave me some other good news that was also a real surprise. DAN-h really glad for you Beth! Getting a promotion is a terrific feeling. I’m sure you’re really going to do well in your new position. BETH-Thanks Dan, it’s nice of you to say that. I’m really excited about it, though I’m a little scared too, I guess. But it’s the other thing my boss told me about that really makes me happy. DAN-Maybe you yesterday.

you could tell me more about thb other news that he gave

What would be the best thing for Beth to say next? (a) I often find that I’m scared by new things. Last year, for instance, I was nervous when I took a night school course for the first time. [Tangential] (b) My boss told me something really terrific yesterday. It’s even better than the news I got about the promotion. [Redundant] (c) He said that they’ll give me a big bonus at Christmas if I get my crew’s production level to go up over the next 6 months. [Most appropriate] Tangential Ending

Scene: Judy sees Sam in the hospital waiting room. JUDY-Sam, the most awful thing has happened. My mother fell on a

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patch of ice in front of her house and may have broken her hip. The doctor called me at the office and told me to come right over. I’m especially worried because of what my mother found out last week. SAM-oh Judy, I’m so sorry to hear that. You must be very worried about her. Have you been here long? JUDY-I’m been waiting around for nearly an hour, and there’s no word on her condition. This whole thing wouldn’t be so bad if it weren’t for what the doctor just told her a couple of days ago. SAM-There nice building,

is a big patch of ice near the building where I live. It’s a though, and I really enjoy living there.

What would be the best thing for Judy to say next? (a) Last week my mother’s doctor warned her to be careful walking around, because her bones are so brittle that any damage would take a very long time to heal. [Return to hint] (b) I actually live in a pretty nice building too, much nicer than where I used to live. It has a doorman on duty 24 hr hours a day, and a garden out in back. [Follow deviation] (c) I’m glad you like your building, but I wanted to tell you that my mother’s doctor warned her specifically to be careful walking since her bones are so brittle. [Most appropriate) Redundant Ending

Scene: Harry meets Lynn in the bakery. LYNN-Hi Harry, I’m glad I ran into you. Joe and I are getting married soon, and we’d love you to come to the wedding. I’m here to order the wedding cake right now. I’m looking forward to settling down, but our honeyman plans are so exciting that I can hardly think of anything else. HARRY-Congratulations Lynn! It’s about time you two made up your minds to get married. I’m sure you’re going to be very happy together, and I’d love to come to the wedding. LYNN-Thanks, I know Joe will be pleased you can come. It’s so hard to concentrate on organizing the wedding when the incredible honeymoon trip we’re planning is what I really want to think about. HARRY-YOU must be getting married soon. Z guess you’re here to order the wedding cake right now.

What would be the best thing for Lynn to say next? (a) Yes, that’s why I’m here. But it’s hard to think about cakes when Joe and I are leaving to go on a safari in Africa right after the wedding. [Most appropriate] (b) Joe and I are planning to go on a one month safari in Africa. I can hardly wait-I’ve dreamed of going there since I was a child. [Return to hint]

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(c) Yes, and they all look so delicious that I’m having a very hard time deciding which kind to get. Maybe you can help me choose. [Follow deviation] REFERENCES Austin, J. L. 1962. How to do things with words. Oxford: Oxford Univ. Press. Bihrle, A. M., Brownell, H. H., Powelson, J. A., & Gardner, X. 1986. Comprehension of humorous and non-humorous materials by left and right brain-damaged patients. Bruin and Cognition, 5, 399-311. Brownell, H. H., & Gardner, H. 1988. Neurological insights into humor. In J. Durant & J. Miller (Eds.), Laughing mafters. London: Longman. Brownell, H. H., Potter, H., Bihrle, A., & Gardner, H. 1986. Inference deficits in right brain-damaged patients. Brain and Language, 27, 310-321. Clark, H. H., & Clark, E. 1977. Psychology and language. New York: Harcourt Brace Jovanovich. Davidson, R. E. 1984. Affect, cognition, and hemispheric specialization. In C. E. Izard, J. Kagan, & R. Zajonc (Eds.), Emotion, cognition, und behavior. New York: Cambridge Univ. Press. Pp. 320-365. Delis, D., Wapner, W., Gardner, H., & Moses, J. A. 1983. The contribution of the right hemisphere to the organization of paragraphs. Cortex, 19, 43-50. Foldi, N. S. 1987. Appreciation of pragmatic interpretation of indirect commands: Comparison of right and left brain-damaged patients. Bruin and Language, 31, 88-108. Gardner, H. 1975. The shuttered mind. New York: Knopf. Gardner, H., Brownell, H. H., Wapner, W., & Michelow, D. 1983. Missing the point: The role of the right hemisphere in the processing of complex linguistic materials. In E. Perecman (Ed.), Cognitive processing in rhe right hemisphere. New York: Academic Press. Geschwind, N. 1976. An approach to a theory of localization of emotion in the human bruin. Paper presented at the International Neuropsychology Symposium: Rot-Amadour, France. Grice, H. P. 1975. Logic and conversation. In P. Cole & J. L. Morgan (Eds.), 5yntu.x und semantics. New York: Academic Press. Vol. III, Pp. 41-58. Heilman, K. M., Bowers, D., & Valenstein, E. 1985. Emotional disorders associated with neurological diseases. In K. M. Heilman & E. Valenstein (Eds.), Clinical neuropsychology. New York: Oxford Univ. Press. Pp. 377-402. Hirst, W., LeDoux, J., & Stein, S. 1984. Constraints on the processing of indirect speech acts: Evidence from aphasiology. Bruin and Language, 23, 26-33. Hough, M. 1990. Narrative comprehension in adults with right and left hemisphere braindamage: Theme organization. Brain and Language, 38, 253-277. Huber, W., & Gleber, J. 1982. Linguistic and nonlinguistic processing of narratives in aphasia. Bruin and Language, 16, 1-18. Joanette, Y., Goulet, P., Ska, B., & Nespoulous, J.-L. 1986. Informative content of narrative discourse in right-brain-damaged right-handers. Brain and Language, 29, 89-105. Johnson-Laird, P. 1983. Mental models. Cambridge: Harvard U. Press. Kaplan, J. A., Brownell, H. H., Jacobs, J. R., & Gardner, H. 1990. The effects of right hemisphere damage on the pragmatic interpretation of conversational remarks. Brain and Language, 38, 315-333. Lezak, M. 1983. Neuropsychological assessment. New York: Oxford Univ. Press. Second ed. Molloy, R., Brownell, H. H., & Gardner, H. 1990. Discourse comprehension by right

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