Journal of Experimental Psychology: Learning, Memory, and Cognition 1992. Vol. 18. No'. 6, 1284-1297

Copyright 1992 by the American Psychological Association. Inc. 0278-7393/92/S3.OO

Direct and Indirect Measures of Memory for Modality in Young and Older Adults Leah L. Light

Donna LaVoie, Debra Valencia-Laver, and Shirley A. Albertson Owens

Pitzer College

Claremont Graduate School

Gale Mead

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Pitzer College In 2 experiments, young and older adults demonstrated modality effects of similar magnitude in perceptual identification tasks. That is, both young and older adults demonstrated more repetition priming when study and test modalities matched than when they were different, suggesting that contextual information was equally available across age. However, when asked explicitly to retrieve modality information, older adults were less accurate than young adults. These results constitute evidence for a dissociation between direct and indirect measures of memory for modality information. They call into question hypotheses that memory impairment in old age is due to deficient encoding of contextual information and challenge current accounts of modality effects in repetition priming.

Contemporary accounts of memory distinguish between mechanisms dependent on familiarity, activation, or perceptual fluency and mechanisms dependent on memory for new associations, either associations between events experienced simultaneously or between events and the environmental or cognitive contexts in which they occur (e.g., Gillund & Shiffrin, 1984; Humphreys, Bain, & Pike, 1989; Jacoby & Dallas, 1981; Mandler, 1980). In particular, activation, familiarity, or perceptual fluency mechanisms have been posited to underlie repetition priming phenomena, whereas context-dependent processes underlie recall and recognition (e.g., Graf & Mandler, 1984; Jacoby & Dallas, 1981). Several lines of evidence converge to suggest that in old age there is relative sparing of activation processes and that age-related deficits in recollection are due to problems in acquisition or utilization of contextual information (e.g., Balota, Duchek, & Paullin, 1989; Light, Singh, & Capps, 1986; Rabinowitz, 1984). In this article, we report two experiments that contradict one aspect of this explanation. We show that memory for context is impaired in old age when direct measures of memory for context requiring explicit report are used but that no age differences exist when memory for modality is tested indirectly. Before reporting the experiments, however, we review

This research was supported by National Institute on Aging Grant AG 02452. We are grateful to P. Gail Mahoney for assistance with analysis of the Experiment 1 data and to Deborah Burke, Darlene Howard, David Mitchell, and Tony Whetstone for helpful comments on an earlier version of this article. Shirley A. Albertson Owens is now at the Department of Psychology, Southern California College. Debra Valencia-Laver is now at the Department of Psychology and Human Development, California State Polytechnic University. Correspondence concerning this article should be addressed to Leah L. Light, Department of Psychology, Pitzer College, Claremont, California 91711. 1284

research supporting the hypothesis that activation processes are immune to the effects of aging whereas context-dependent processes are not. Evidence that activation is spared in old age comes from two rather different paradigms, namely, semantic priming and repetition priming. First, studies of semantic priming in lexical decision and word naming reveal no differences in the extent or breadth of activation (e.g., Balota & Duchek, 1988; Howard, McAndrews, & Lasaga, 1981; Nebes, Boiler, & Holland, 1986). Such studies are generally interpreted as supporting preserved activation processes (e.g., Howard, 1988a), although the spreading activation account of semantic priming has been challenged (Ratcliff & McKoon, 1988). Second, when compared with young adults, older adults show impaired retention on direct measures of memory such as recall and recognition. On indirect measures of memory that do not require deliberate recollection, however, age differences are either small or nonexistent (see Light, 1991, for a review). Thus, the magnitude of repetition priming appears to be relatively stable over the adult years. Similar levels of repetition priming across age have been found for word fragment completion (Light et al., 1986), word stem completion (Howard, 1988b; Light & Singh, 1987), perceptual identification of degraded words (Light & Singh, 1987), picture naming (Mitchell, 1989; Mitchell, Brown, & Murphy, 1990), lexical decision (Moscovitch, 1982), category judgments (Rabbitt, 1982, 1984), and spelling of homophones in accordance with previously biased meanings (Howard, 1988b). Although some studies have reported reliable age differences in these tasks (Chiarello & Hoyer, 1988; Davis et al., 1990; Hultsch, Masson, & Small, 1991; Rose, Yesavage, Hill, & Bower, 1986), when the same individuals are compared on direct memory tests (recall or recognition) and indirect memory tests (repetition priming paradigms), age differences are typically small and unreliable on indirect measures and substantial and reliable on direct measures. On the assumption that activation

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MEMORY FOR MODALITY IN YOUNG AND OLDER ADULTS

mechanisms underlie repetition priming, finding age invariance on repetition priming tasks constitutes evidence for preserved activation in old age. Evidence that contextual information about experiences is less available in old age comes from studies that require the reporting of nonsemantic attributes of events. Such studies generally find that older adults are less adept at monitoring the sources of information they have received. For instance, they are not as good at recalling whether information was presented auditorily or visually (Kausler & Puckett, 1981a; Lehman & Mellinger, 1984, 1986; Mclntyre & Craik, 1987), in uppercase or lowercase letters (Kausler & Puckett, 1980, 198 la), in a male voice or a female voice (Kausler & Puckett, 1981b), or in a particular color (Park & Puglisi, 1985). Similarly, older adults have more difficulty than young adults in remembering whether they saw a word or generated it from a clue (Mitchell, Hunt, & Schmitt, 1986; Rabinowitz, 1989), in remembering whether they learned a fact in an experimental setting or knew it before (Janowsky, Shimamura, & Squire, 1989; Mclntyre & Craik, 1987), in deciding whether they thought or said a word (Hashtroudi, Johnson, & Chrosniak, 1989), and in remembering which of two orienting tasks they used for a word during encoding (Brigham & Pressley, 1988; Mueller, Wonderlich, & Dugan, 1986). Older adults are also more susceptible to the effects of misleading information presented after they witness a series of events, suggesting that they are confused about the source of the information (Cohen & Faulkner, 1989). In addition, older adults are more likely than young adults to call a previously seen name or face "famous" when it is encountered later, indicating faulty source attribution (Bartlett, Strater, & Fulton, 1991; Dywan & Jacoby, 1990). Finally, an extensive literature documents age-related impairment for spatial and temporal information (see Kausler, 1990, for a review). Thus, considerable evidence points to reduced ability to deliberately retrieve contextual information in old age. Still, the conclusion that context-dependent processes are impaired in old age may be premature. Memory for contextual information in old age has been assessed almost exclusively by direct measures. That is, people have been asked to recollect particulars of the study experience, such as its modality. Given the finding of equivalent performance of young and old when memory for content is tested by indirect means, it is possible that memory for context will also prove to be age-invariant under conditions that do not require deliberate recollection. In the two experiments reported in this article, we put this hypothesis to the test by comparing young and older adults on both direct and indirect measures of memory for one type of contextual information, the modality in which words were studied. In each study, half of the words were presented visually and half were presented auditorily. The direct measure of memory for context was a recognition memory test in which previously presented words were intermixed with new words; the subject's task was to indicate for previously presented words whether they had been seen or heard initially. The indirect measure of memory for context was a perceptual identification test, with test modality matching input modality for half of the items and test modality being different for the remaining half. In Experiment 1, the

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perceptual identification test was visual identification of briefly presented words; in Experiment 2, it was ability to identify words presented auditorily in noise. Our indirect measure of context capitalizes on the fact that repetition priming is sensitive to changes in the physical format of items between study and test. Repetition priming is attenuated, though usually not eliminated, when there is a mismatch between study and test in modality, case, or script (e.g., Clarke & Morton, 1983; Jacoby & Dallas, 1981; Jacoby & Heyman, 1987; Roediger & Blaxton, 1987). This outcome is inconsistent with the idea that repetition priming depends solely on the activation of ahistorical memory units—that is, memory units that do not record the contextual details of individual episodes. Rather, the modality effect in repetition priming seems most consistent with a two-process view of repetition priming in which both activation and memory for contextual information play a role (e.g., Feustel, Shiffrin, & Salasoo, 1983). Kirsner, Dunn, and Standen (1989) have suggested that repetition priming effects can be decomposed into two components, one that is specific to modality of presentation and one that is nonspecific. The specific component is reflected in the greater magnitude of repetition priming when modality is the same between study and test, whereas the nonspecific component is manifest in the superiority of different-modality test items over new items. If older adults store less information about context, and if modality effects in repetition priming depend on the availability of precise information about specific episodes, we might expect to find that older adults would demonstrate smaller modality effects in perceptual identification as well as reduced ability to deliberately recollect input modality. In particular, the logic of Kirsner et al. (1989) would lead us to expect that the difference in accuracy for items originally studied in the test modality and those studied in another modality would be greater for young than for old because of decreased memory for modality-specific information in the old. The same logic would lead to the prediction that nonspecific priming effects reflected in improved perceptual identification of items presented in different modalities at study and test over new items should be constant across age to the extent that activation is unimpaired in normal aging. The findings reviewed above do not jibe with this prediction, however. Evidence has been presented that the overall level of repetition priming is about the same in young and old. If the modality-specific component of repetition priming were reduced in old age, then it would be surprising to find undiminished overall repetition priming effects in the old— unless there were a compensatory increase in the nonspecific component of priming. Such an increase would suggest that activation increases in old age as well, inasmuch as activation underlies nonspecific priming. Although there is some evidence that activation processes become increasingly important in old age relative to context-dependent processes (Jennings & Jacoby, 1992; Light, 1988), we know of no reason to suggest that the absolute amount of activation is greater in the old. Hence, we have no reason to expect that when overall levels of repetition priming remain constant, the contributions of either the modality-specific component or the nonspecific component of priming will fluctuate with age.

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All of this suggested to us that age decrements in intentional recollection of contextual information might coexist with unimpaired utilization of contextual information in tasks that do not require deliberate recollection of that information. Interestingly enough, such a situation appears to exist in anterograde amnesia. Graf, Shimamura, and Squire (1985) found that severely impaired anterograde amnesics, whose free-recall levels were much lower than those of controls, displayed normal modality effects in repetition priming. Although there do not appear to have been any studies specifically comparing amnesics and controls on deliberate recollection of modality information, Pickering, Mayes, and Fairbairn (1989) reported that amnesics were less able to report whether they had read words aloud or had heard them spoken by an experimenter; amnesics are also known to have poor source memory in other paradigms (Schacter, Harbluk, & McLachlan, 1984). Our aim, then, was to determine whether a similar pattern would emerge for older adults. To anticipate our results, we found no age differences in the size of the modality effect in repetition priming in either of the experiments reported here but consistent age differences, favoring the young, in the likelihood of recalling the modality of words correctly recognized as being from the study list. After describing the two experiments, we discuss the implications of our findings for the hypothesis that activation processes are preserved in old age but that processes involving storage or utilization of contextual information are impaired. Experiment 1 Experiment 1 had two goals. The primary goal was to compare young and older adults on both direct and indirect measures of memory for modality. Young and older adults first made judgments about a list of words (see Materials section), half presented visually and half auditorily. They were then tested for visual perceptual identification. Words were flashed briefly on the screen of a monitor, and repetition priming was assessed by comparing accuracy for previously seen words, previously heard words, and new words. Finally, subjects received a recognition memory test in which they identified previously studied items as "saw" or "heard." To permit assessment of the effects of seeing target words on the perceptual identification task (as well as experiencing them either auditorily or visually on the original study list) on subsequent ability to report input modality for correctly recognized words, only half of the items originally seen or heard were tested for perceptual identification. The remaining half of the originally seen or heard words also appeared on the recognition test and provided a purer measure of recollection of input modality without interference from the perceptual identification task. The magnitude of the modality effect in the perceptual identification test constituted an indirect measure of memory for contextual information. The recognition test, which required an explicit choice of modality for items judged as having been previously presented, constituted a direct measure of memory for contextual information. On the basis of prior research, we expected to observe age differences on the direct measure. At issue was whether the size of modality effect in perceptual identification would vary with age.

A secondary goal of Experiment 1 was to determine whether modality effects in repetition priming depend on the nature of the orienting activities carried out when target items are presented for study. Perceptual identification is less affected by manipulations of orienting tasks than recognition memory is (Hashtroudi, Ferguson, Rappold, & Chrosniak, 1988; Jacoby & Dallas, 1981; Light & Singh, 1987), suggesting that data-driven processes play an important role in perceptual identification. This idea is bolstered by the fact that perceptual identification is sensitive to variations in study and test modalities. The robust finding of cross-modal priming in perceptual identification, however, suggests that conceptually driven processes are also operative. Because conceptually driven processes are thought to be affected by the nature of the orienting task during study (Srinivas & Roediger, 1990), we might expect that the nonspecific component of repetition priming in perceptual identification would be responsive to variations in encoding task, whereas the modality-specific component of repetition priming would not be. Given that the total amount of priming (same modality vs. new items) seems to be about the same regardless of orienting task, this does not seem likely. More plausible here is that the relative contributions of data-driven (modality-specific) and conceptually driven (nonspecific) processes would shift with different orienting tasks. Interestingly enough, MacLeod and Bassili (1989) made just this prediction. They conjectured (but offered no evidence) that orienting tasks that encourage processing of relational (contextual and associative) information rather than item-specific information should lead to reduced encoding of modality-specific information and a reduction in the size of the modality effect in indirect memory tasks. We should also point out that a parallel prediction can be made about deliberate recollection of modality—if MacLeod and Bassili are correct, direct measures of modality should also be negatively affected by processing of relational information. To investigate these matters, we asked half of the participants in Experiment 1 to rate words for pleasantness during study and half to perform a task designed to focus on nonsemantic aspects of the study words. The latter task was to count the number of syllables in the word silently and to report that number. If the pleasantness-rating task, which presumably fosters relational encoding, reduces the amount of modality-specific information that is stored, the modality effect should be smaller in the pleasantness-rating condition than in the syllable-counting condition; the amount of nonspecific priming should be correspondingly larger for the pleasantness-rating task, so that overall priming remains constant across orienting tasks.

Method Subjects. Thirty-two young adults (18 women and 14 men) and 32 older adults (18 women and 14 men) participated in Experiment 1. The young adults (mean age = 21.75 years, range = 18-32) were graduate and undergraduate students of the Claremont Colleges, and the older adults (mean age = 71.72 years, range = 64-80) were residents of the Claremont community, many being alumni of the Claremont Colleges. The older adults had somewhat more years of education (mean = 17.31 years) than the young (mean = 15.06 years),

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MEMORY FOR MODALITY IN YOUNG AND OLDER ADULTS F(l, 62) = 13.40, MSe = 6.04. Older adults also had higher scores (mean = 22.03) than young adults (mean = 18.22) on a 25-item version of the Nelson-Denny Vocabulary Test (1960), F(l, 62) = 26.88, MSC = 8.65. Both groups reported themselves to be in good health, with mean ratings of 8.38 for the young and 8.00 for the old (maximum = 10). Data from nine additional older adults were excluded from analysis; four had hearing problems, three had perceptual identification baselines (see Procedures section) that were too high (.70 or greater), and two were unable to follow the instructions. Data from one additional young adult whose perceptual identification baseline was too low (less than .10) were also excluded. Subjects were paid $5 for their participation. Materials. Two target lists of 80 words were prepared. Each list consisted of 80 nouns, five to nine letters in length and containing one to four syllables; the Francis and Kucera (1982) word frequencies ranged from 1 to 20. Half of the words in each list were presented auditorily and half visually. Order of words within lists was random, with the restriction that no more than two words could appear successively in either modality. Counterbalancing presentation modality resulted in four lists, two of which were mirror images of the other two with respect to presentation modality. These four lists were used equally often for participants in both age groups and orienting conditions. All lists were presented on a Macintosh SE computer. Auditorily presented words werefirsttape-recorded and then digitized for presentation on the Macintosh. Procedure. Thefirsttask was designed to familiarize participants with speech presented by the Macintosh. A list of 20 words similar to those used in the experiment was presented for perceptual identification; subjects unable to report at least 16 words correctly were replaced (see Subjects section). Following this screening task, the target list was presented at a 5 s/word rate. Subjects were given a cover story explaining that the purpose of the study was to norm materials for future use; there was no mention of a subsequent memory test. Half of the subjects in each age group rated the words for pleasantness (1 = very pleasant, 5 = very unpleasant) and half counted the number of syllables contained in each word. All responses were given orally and recorded by the experimenter, but subjects did not repeat the words themselves aloud. Ten practice items were given to familiarize subjects with the rating tasks prior to list presentation. The perceptual identification task followed list presentation. The first part of the task consisted of a procedure to establish durations that would yield about 50% correct identification for previously unstudied items. Thirty-six items were presented during this portion of the task. A 500-ms prompt, consisting of horizontal arrows pointing to the space where the target would appear, began each trial. The arrows were replaced by a pattern mask for 500 ms and were followed by the target for a variable duration. After the target had been on the screen for its allotted duration, the pattern mask was superimposed on it for 500 ms. The first four items were presented at a rate of 150 ms/item. After each of the four items, presentation duration decreased by 1 tic (16.67 ms) until a duration of 1 tic was reached. The duration at which 50% of the items were identified was used for a practice session of 40 additional items, during which the presentation duration was further adjusted to maintain the desired baseline accuracy. The mean presentation durations were 43 ms for the young (range = 3383) and 74 ms for the old (range = 33-149). The main perceptual identification task was then given after a break for instructions. There were 120 items on this test, 40 from the study list (20 auditory, 20 visual) and the 80 previously unstudied items from the alternate target list. Subjects were instructed to respond as quickly and accurately as possible by saying out loud the word they thought they had just seen. They were asked to respond to all items and to guess if uncertain. After each item, the target was shown on the monitor and the subject was queried by the program as to whether the response given was the target; the experimenter recorded accuracy at this point.

A written recognition test was given after the perceptual identification task. This test included all 80 of the originally studied words, 40 words from the alternate study list (which had also appeared on the perceptual identification task), and 40 new distractors that had not been seen or heard previously during the experiment. Order of items on the test was random with two restrictions: (1) no more than three previously presented words could appear consecutively, and (2) all distractors that appeared on the perceptual identification test were in the first half of the recognition test. Our experience suggests that performance on recognition tests deteriorates as subjects progress through the test. Placing the presumably more difficult distractors early in the test was designed to reduce the difficulty of these, especially for older adults. Although this introduces a confound between order and perceptual identification task status (present vs. not present), this confound was eliminated in Experiment 2. Next to each word on the recognition test were the responses "saw" and "heard." Participants were asked to circle "saw" for items seen in the original study list, "heard" for items heard in the original study list, and neither answer if they had neither seen nor heard the test item in the original list.

Results and Discussion The results of the perceptual identification task are discussed first, followed by those of the recognition and modality judgment test. Unless stated otherwise, the significance level was set at .05 for all statistical tests. Perceptual identification. The mean proportions of correctly identified words are given in Table 1 as a function of age, orienting task, and item status (saw, heard, new). Table 2 gives the magnitudes of the overall priming effect (SawNew), the modality-specific priming component (SawHeard), and the nonspecific priming component (HeardNew). Examination of Tables 1 and 2 suggests that the modality effect in repetition priming is robust and varies with neither age nor orienting task. A 2 (age) x 2 (orienting task) x 3 (item status: saw vs. heard vs. new) analysis of variance bears out these observations. There was a main effect of item status, F(2, 120) = 86.26, MSt = 0.006. Previously seen items were identified best (.665), followed by previously heard items (.578) and new items (.485). Planned comparisons indicated reliable repetition priming for both originally seen items, F(\, 60) = 169.46, Table 1 Proportions Correct and Standard Deviations of Perceptual Identification as a Function of Age and Item Status in Experiments 1 and 2 Young Experiment Saw Heard Experiment 1 Syllable count P .606 .509 SD .189 .170 Pleasantness P .703 .594 SD .219 .201 Experiment 2 P .457 .495 SD .193 .152 Note. Test modalities are in bold.

Older New Saw Heard New .427 .693 .189 .137

.630 .131

.540 .131

.471 .658 .170 .140

.578 .141

.503 .144

.397 .443 .166 .122

.498 .112

.378 .134

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Table 2 Magnitude of Priming in Experiments 1 and 2 Older Components of priming Young Experiment 1 Syllable count .179 .153 Overall priming .097 .063 Modality-specific priming .082 .090 Nonspecific priming Pleasantness .232 Overall priming .155 .109 .080 Modality-specific priming .123 .075 Nonspecific priming Experiment 2 .098 .120 Overall priming .038 .055 Modality-specific priming .060 .065 Nonspecific priming Note. For Experiment 1, Overall priming = Saw - New; modalityspecific priming = Saw - Heard; and Nonspecific priming = Heard - New. For Experiment 2, Overall priming = Heard — New; Modality-specific priming = Heard — Saw; and Nonspecific priming = Saw - New.

MSe = 0.006, and originally heard items, F(l, 60) = 58.66, MSe = 0.005. The difference between previously seen and previously heard items, that is, the modality effect, was also reliable, F(\, 60) = 33.73, MSe = 0.007. Neither the main effect of age (F = 1.60) nor the interaction between age and item status (F — 1.87) was reliable. Moreover, there were no main effects or interactions involving orienting task (all Fs < 2.29). Recognition. For each participant, we obtained both a hit rate and a false alarm rate. Hit proportions were computed by summing the proportions of words that subjects correctly indicated as studied items by responding either "saw" or "heard"; this was done separately for previously seen and for previously heard items. These proportions are shown in Table 3 as a function of age, orienting task, and input modality. False alarms, also shown in Table 3, were defined as unstudied (new) items to which subjects responded either "saw" or "heard," thereby indicating an erroneous belief that these items had been studied previously.

A 2 (age) x 2 (orienting task) x 2 (input modality) x 2 (tested on perceptual identification task [PI] vs. not tested on perceptual identification task [non-PI]) analysis of variance (ANOVA) was conducted on the proportions of hits. There was a main effect of orienting task, F(l, 60) = 63.34, MS, = 0.094; rating pleasantness produced a higher hit rate (.845) than did syllable counting (.541), the well-known levels of processing effect. Also, items that appeared on the PI task as well as on the original list were more often correctly identified as old (.738) than items not appearing on the PI task (.648), F{\, 60) = 37.33, MS, = 0.014. Two interactions were also reliable, those between orienting task and input modality, F(l, 60) = 5.85, MS, = 0.008, and between orienting task and presence on the PI task, F(l, 60) = 16.59, MS, = 0.014. Examination of the cell means for the Orienting Task x Input Modality interaction suggests that the superiority of the pleasantness-rating task over the syllable-counting task was somewhat greater for visually presented items (.867 vs. .536) than for auditorily presented items (.823 vs. .545); this interaction is not large. The interaction between orienting task and presence on the PI task appears to be the result of ceiling effects in the pleasantness condition, where the proportions of hits were .860 for PI items and .830 for non-PI items, but not in the syllable-counting task, where the corresponding proportions were .615 and .466. Hit rates were nearly identical for young (.702) and older adults (.684) (F < 1) and age did not interact with any other variable (all i-s < 1.15). The false alarm data were submitted to a 2 (age) x 2 (orienting task) x 2 (PI vs. non-PI) ANOVA. There were main effects of both age, F(l, 60) = 4.06, MS, = 0.093, and presence on the PI task, F(l, 60) = 58.39, MS, = 0.019. Older adults made more false alarms (.270) than young adults (. 162). Items that appeared on the PI task were more likely to be called "old" erroneously (.310) than non-PI items (.123). There was no evidence of an interaction between age and presence on the PI task (F < 1). Memory for presentation modality. The conditional probability of specifying the input modality for items correctly identified as "old" was computed for each subject for all

Table 3 Proportions and Standard Deviations of Hits and False Alarms in Experiment 1 Non-PI items

PI items FA Hits—saw Hits—heard Age Young Syllable count P .612 .634 .278 .176 .234 SD .163 Pleasantness P .909 .834 .219 .080 .122 .252 SD Older Syllable count .591 .622 .374 P .206 .268 .262 SD Pleasantness .831 .367 P .866 SD .172 .149 .299 Note. FA = false alarm; PI = perceptual identification.

Hits—saw

Hits—heard

FA

.469 .160

.447 .172

.066 .056

.866 .136

.847 .090

.084 .215

.472 .263

.478 .260

.164 .249

.828 .132

.781 .126

.177 .244

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MEMORY FOR MODALITY IN YOUNG AND OLDER ADULTS

combinations of input modality and presence on the PI task. These conditional probabilities (shown in Table 4) were subjected to a 2 (age) x 2 (orienting task) x 2 (input modality) x 2 (PI vs. non-PI) ANOVA. The ANOVA deleted the data of one older adult who did not contribute entries to all cells. There were main effects of age, modality of presentation, and presence on the PI task. Young adults were more accurate (.779) than older adults (.643) in correctly identifying presentation modality, F(l, 59) = 21.09, MSC = 0.055. Visually presented items were correctly identified more often (.752) than auditorily presented items (.673), F(l, 59) = 6.76, MSC = 0.060. And items that had been presented on the PI task fared worse (.676) in the modality judgment task than items that had not (.749), F(l, 59) = 18.46, MS, = 0.017. Interpretation of these main effects must be qualified because of the presence of a reliable interaction between input modality and presence on the PI task, F(l, 59) = 13.71, MSe = 0.024, and a nearly reliable triple interaction of these variables with orienting task, F(l, 59) = 3.95, MS, = 0.024, p = .052. Inspection of the means entering into these interactions indicates that there was no effect of input modality for items that did not appear on the PI task, with means of .751 for previously seen items and .743 for previously heard items. However, modality identification was depressed for items on the PI task that were originally heard (.600) relative to those that were originally seen (.752). This pattern was stronger for the syllable-counting task than for the pleasantness-rating task. Thus, judging input modality of items is harder when that judgment also involves keeping track of whether an item appeared in the most recent task. This was especially true for previously heard items in the syllable condition that had appeared on the PI task as well as on the original list. The interaction of age and presence on the PI task was nearly significant, F{\, 59) = 3.64, MSe = 0.017, p = .061. This interaction arises from the fact that the difference between young and old was larger for the non-PI items (.830 vs. .663) than for the PI items (.728 vs. .624). There were two

Table 4 Conditional Probabilities and Standard Deviations of Correct Modality Judgments in Experiment 1 PI items Age

Saw

Young Syllable count Conditional P .811 SD .110 Pleasantness Conditional P .843 SD .124 Older Syllable count Conditional P .757 SD .178 Pleasantness Conditional P .596 SD .246 Note. PI = perceptual identification.

Non-PI items

Heard

Saw

Heard

.545 .206

.802 .154

.776 .218

.713 .166

.886 .096

.858 .113

.548 .237

.647 .266

.639 .263

.594 .215

.669 .224

.698 .230

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more marginally significant interactions involving age, which are reported here for completeness. These were the two-way interaction of age and orienting task, F( 1,59) = 2.87, MSe = 0.055, p = .10, and the three-way interaction of these two variables with presence on the PI task, F(l, 59) = 2.94, MSe = 0.017, p = .092. Given the suggestion of these interactions, and because judgments for those items that did not appear on the PI task provide the cleanest comparison with the perceptual identification data, we carried out separate ANOVAs for the PI and non-PI conditions. For items not appearing on the PI task, only the main effect of age was reliable F(l, 59) = 20.02, MSe = 0.044; young adults were more accurate on this measure (.831) than older adults (.664). For items that had been on the PI task, the young (.728) outperformed the old (.623), F(l, 59) = 12.07, MSe = 0.028. Also, modality judgments were better for previously seen items (.752) than for previously heard items (.601), F(l, 59) = 16.36, MS, = 0.044. Two interactions were reliable in this ANOVA, those between orienting task and age, F(l, 59) = 6.86, MS, = 0.028, and between orienting task and input modality, F(\, 59) = 5.22, MS, = 0.044. The first of these interactions is due to the fact that young and old performed about the same after counting syllables, with means of .678 for the young and .652 for the old, but the young were more accurate (.778) than the old (.595) after rating words for pleasantness. The second interaction reflects the fact that the modality of previously seen items was better remembered after syllable counting (.784) than after pleasantness rating (.720), whereas the modality of previously heard items was better reported after pleasantness rating (.654) than after syllable counting (.546). We do not have a ready explanation of these findings. The lack of a consistent effect of orienting task on modality judgments, however, is inconsistent with the view that semantic processing reduces the amount of modality-specific information available for reporting. Because young adults were more accurate than older adults on the modality judgment task, and given the marginal interaction between age and presence on the PI task, it is important to ascertain whether older adults' performance exceeded chance in all conditions. In fact, for older adults, the probability of making a correct modality judgment was better than chance (.50) for all non-PI conditions (all ts > 2.05), whereas their performance in PI conditions was better than chance only for previously seen items in the syllable condition (t = 5.59) and for previously heard items in the pleasantness-rating condition (/ = 1.75). Young adults' proportions of correct modality judgments were better than chance (all rs > 5.07) for all but heard items in the syllable condition that appeared on the PI task. Finally, we examined the false alarm data for evidence of differential response bias in young and older adults. None was found. For young adults who made false alarms, the proportion of false alarms that were "saw" responses was .552 of the total, whereas for older adults who made false alarms, the proportion of "saw" responses among these false alarms was .568 (F < 1). As might be anticipated, the proportion of "saw" responses was greater for false alarms made to PI items (.692) than to non-PI items (.430), F(l, 43) = 21.66, MS, = 0.070. However, there was no hint of an interaction between

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age and PI status (F< 1). Thus, older adults did not seem to be especially disadvantaged by the presence of items on the PI task; this result parallels that for the overall false alarm data. To summarize the results of Experiment 1, the perceptual identification task replicates previous research by showing that the overall magnitude of repetition priming is unaffected by age. What was true for the overall priming effect was also true for each of its components. There was no age difference in the magnitude of nonspecific priming; young and older adults benefited from hearing target words to the same extent, suggesting that activation is preserved in old age. More important, the results of the perceptual identification task also suggest that modality information is equally available in the memories of young and older adults, because there was no age difference in the size of the modality effect in repetition priming; young and older adults benefited to the same degree from having modality remain constant for study and test. Nevertheless, the modality judgment task, which required deliberate recollection of whether an item identified as belonging to the study list had been seen or heard, produced age differences. The observed pattern of findings is similar to that seen in anterograde amnesia, where modality effects appear to be normal but source memory is impaired. The perceptual identification task was also insensitive to variations of the orienting task used during study, replicating prior work. No interaction was observed between orienting task and the magnitude of either the modality-specific component or the nonspecific component of repetition priming. Thus, contrary to the conjecture of MacLeod and Bassili (1989), we found no evidence that pleasantness rating, which presumably increases relational encoding, decreases item-specific encoding. Nor did we find evidence that the nonspecific component of repetition priming is sensitive to orienting task. If the nonspecific component is mediated by conceptually driven processes, what we seem to have here is an instance of conceptually driven processing that does not respond to orienting tasks. Nonspecific priming effects in perceptual identification may be mediated by processes other than those operative in other conceptually driven memory phenomena. Alternatively, nonspecific priming may not be conceptually driven. Kirsner et al. (1989), however, summarized a number of studies showing that nonspecific priming is more responsive to variations in word frequency than is modality-specific priming, a finding consistent with a role for conceptually driven processing in nonspecific priming. Resolution of this issue awaits further investigation. Experiment 2 In Experiment 1, the perceptual identification test was visual, and indeed, all previous repetition priming studies comparing young and older adults have involved vision. The primary goal of Experiment 2, then, was to determine whether the same pattern offindingswould be observed in an auditory task, namely, identifying words presented in noise. Hearing loss in old age is well documented (Olsho, Harkins, & Lenhardt, 1985). Although we screened participants for ability to perceive auditorily presented words in Experiment 1, we were concerned that modality effects in visual word identification

could arise for the old as an artifact of not hearing some of the words correctly. That is, if older adults missed more formerly heard words than formerly seen words on the perceptual identification task, this could have been because they had not heard some of those words correctly when presented originally rather than because they had not preserved information about input modality. This seemed unlikely inasmuch as there were no interactions of age and input modality for hits on the recognition test in Experiment 1, but finding age constancy in modality effects in an auditory identification task would remove any possible ambiguity about this matter. Moreover, finding a modality effect in repetition priming in Experiment 2 would eliminate any doubt that the modality effect in Experiment 1, which involved visual perceptual identification, resulted from the longer presentation time of visual items than of auditory items. A secondary goal of Experiment 2 was to explore a phenomenon reported by Jacoby, Allan, Collins, and Larwill (1988). These investigators found that when previously studied material was presented in noise, the background was judged as quieter than when new material was presented in the same noise. This effect was explained as an attribution based on perceptual fluency. Previously presented material is easier to perceive, and the subjective experience is of relative loudness of the material as compared to the background noise. Loudness judgments constitute an indirect measure of memory because people are not asked to deliberately recollect anything but simply to rate their subjective experiences. We were interested in determining whether older adults would demonstrate preserved memory when tested in this way.

Method Subjects. Thirty-two young adults (18 women and 14 men) and 32 older adults (22 women and 10 men) drawn largely from the same populations as those in Experiment 1 participated in Experiment 2. The mean age of the young adults was 24.36 years (range = 18-33) and that of the older adults was 70.48 years (range = 58-78). Young and older adults were closely matched in educational level; the mean numbers of years of schooling were 15.39 for the young and 15.88 for the old (F < 1). However, as we have found before, the old outperformed the young on our 25-item version of the Nelson-Denny Vocabulary Test. The mean scores were 15.25 for the young and 20.38 for the old, F(l, 62) = 59.83, MS, = 7.02. Although there was a reliable age difference in reported health favoring the young, F(l, 62) = 4.11, MSt — 1.52, both groups thought themselves to be in good health, with means of 8.66 for the young and 8.03 for the old. Data from an additional 3 young adults who were not native speakers of English were excluded from analysis. Four additional older adults did not understand task instructions, and 1 older adult had a selfreported hearing problem. Also, 1 young and 1 older adult had baselines below .20 on the perceptual identification task. The data from these 10 people were not included in the analyses. All subjects were paid $8 for participating in the experiment. Materials. Two word lists were prepared for use in Experiment 2. The construction of these lists paralleled that of the lists in Experiment 1. Each list contained 60 words ranging in length from one to four syllables (three to nine letters), with Francis-Kucera (1982) word frequencies between 25 and 40. Within each list, half of the words were presented auditorily and half visually, with the constraint that no more than 4 words in a row could be in the same modality. A further five buffer words appeared at the beginning of

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MEMORY FOR MODALITY IN YOUNG AND OLDER ADULTS the list and five at the end. Counterbalancing presentation modality across lists resulted in four presentation lists that were used equally often for young and older adults. Visually presented words were printed in 24-point lowercase bold Geneva on 5 x 8 in. white note cards. The auditory portions of the lists were recorded on both channels of a JVC model TD-W301 cassette tape deck through a microphone attached to an Ampex sound mixer. Subjects listened to the list through a set of Sony MDR-V6 headphones connected to a Sony STR-AV310 amplifier. Amplifier playback was controlled by the sound mixer and an audio attenuator interfaced with the cassette tape deck. The loudness level for items studied auditorily was 70 dB. Procedure, Subjects performed four tasks during the experimental session. The first was to make judgments of pleasantness on a 5-point scale (1 = very pleasant, 5 = very unpleasant) as the target list was presented at a 7 s/item rate. The experimenter held up cards for visually presented words as the tape was presented; the tape was silent during visual presentation of words. As in Experiment 1, subjects were led to believe that materials were being normed for future use, and no mention of a forthcoming memory test was made. Pleasantness ratings were given orally and were recorded by the experimenter. The second task was identification of words presented in noise. Words were recorded on the right channel of the tape, and white noise was recorded from an H. R. Scott model 811 random noise generator on the left channel of the tape; when played back through the sound mixer, words and noise were on a single channel. The first phase of this task was to determine a noise level that would produce 50% correct identifications of previously unstudied words for each subject. The volume of the voice speaking the words was initially set at 70 dB, and the noise level was fixed at 80 dB. A modified method of limits (i.e., a series of alternating ascending and descending changes in voice volume) was used, with the volume of the voice increasing or decreasing in steps of 0.4 dB. The mean reduction in voice volume was 0.685 dB for the young (range = 0.23-1.13 dB) and 0.867 dB for the old (range = 0.20-1.60 dB). After voice volume was determined, the subject received a list of 20 new words to identify with voice level set at the individual's level without background noise. In the absence of noise, performance was at 100% accuracy for all participants. The final, critical, phase of the perceptual identification task followed. In this task, subjects were presented with a list of 120 words, 30 from the originally studied list (15 auditory, 15 visual), 30 from the alternate study list, and 60 fillers. The 30 old words and the 30 words from the alternate list were all presented with background noise loudness set at 80 dB. The background loudness of the remaining 60 items was 60 dB, 65 dB, 70 dB, or 75 dB, with 15 items at each level. Thus, over the entire list, five levels of background noise were used. Subjects attempted to identify each item as it was spoken, guessing if unsure, and also judged the loudness of the background noise for each item on a 5-point scale (1 = very quiet, 5 = very loud). To familiarize subjects with the noise judgment procedure, 20 practice trials (4 words at each of the five noise levels) were also given. The recognition memory test was administered immediately after the perceptual identification task. This test included all 60 of the originally studied items (30 of which had also been presented for perceptual identification), 30 distractors from the alternate target list, which had also appeared on the perceptual identification task, and 30 completely new distractors. Subjects were asked to read each word and to circle "saw" if they had seen the word originally, "heard" if they had heard the word originally, or "new" if the word had not been presented in the original study list.

Results and Discussion Perceptual identification. The data of interest here are the proportions of words correctly identified in 80 dB of background noise. Mean proportions of items correctly identified

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by young and older adults are given in Table 1 for previously heard words, previously seen words, and new (baseline) words. Examination of Table 1 reveals that previously heard words were recognized best (.496) followed by previously seen words (.450) and new items (.388). A 3 (item status: saw vs. heard vs. new) x 2 (age) ANOVA confirmed this visual impression. There was a reliable main effect of item status, F(2, 124) = 20.64, MSC = 0.009. Additional planned comparisons indicated that repetition priming (see Table 2) was reliable for both heard and seen items, F(\, 62) = 40.94, MSe = 0.009, and F(l, 62) = 17.19, MSC = 0.007, respectively. Most important, the difference in correct identifications for previously heard and seen items was reliable, F(\, 62) = 6.14, MSe = 0.011. There was neither a main effect of age nor an Age x Item Status interaction (both Fs < 1). Thus, these results replicate those of Experiment 1 in demonstrating equivalent modality effects in repetition priming for young and old. Indeed, in Experiment 2, the amount of repetition priming and the size of each of its components was slightly larger for the old than for the young. One potential problem with our conclusions is that effect sizes (Borenstein, Cohen, Rothstein, Pollack, & Kane, 1990) were generally small for comparisons between the magnitudes of priming in young and older adults, with most falling in the small range (< .25), and estimates of power were correspondingly low, with most values less than .20 in both Experiments 1 and 2. Small effect sizes are, of course, compatible with our belief that age differences in repetition priming are small or nil. This belief is reinforced by the outcomes of two analyses that boosted power by combining across the two experiments. The first of these involved combining the data from the two experiments (collapsing across orienting tasks in Experiment 1) and carrying out two 2 (age) x 2 (experiment) ANOVAs, one for the modality-specific priming effect (saw vs. heard) and one for the nonspecific priming effect. In neither ANOVA was there a main effect of age, F(l, 124) = 0.47 for the modality-specific effect and F(l, 124) = 1.39 for the nonspecific effect. There was, however, a reliable interaction between age and experiment for the modality-specific priming component, F(l, 124) = 4.27, MSe = 0.017, reflecting the fact that there was a bigger effect for the young in Experiment 1 and a bigger effect for the old in Experiment 2. The second method we used was a meta-analytic technique described by Winer (1971, p. 50), which produced a z statistic based on the t values for comparing young and old; the zs obtained for the modality-specific and nonspecific components of repetition priming were both less than 1. Hence, even doubling our sample sizes by combining across experiments failed to produce reliable age effects, again no doubt because the direction of the effects was opposite in the two studies. Recognition. Mean proportions of hits and false alarms are shown in Table 5. Two ANOVAs were conducted to determine whether young and older adults differed in discrimination of items that had been studied originally and items that had not been studied originally. A 2 (previously seen vs. previously heard) x 2 (PI vs. non-PI) x 2 (young vs. old) analysis of variance was carried out on the proportion of recognition hits. There were no reliable main effects of input modality (F < 1), presence on the PI task (F < 1), or age, F( 1, 62) = 1.05, MSe = 0.058. Nor were any of the interactions

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reliable (all Fs < 2.36). A 2 (PI vs. non-PI) x 2 (age) analysis of variance conducted on the false alarm rates yielded a main effect of age, F(\, 62) = 4.15, MS, = 0.081, with older adults making more false alarms (.405) than young adults (.303). There were more false alarms for items that had been on the PI task (.378) than for items that had not been (.330), F(l, 62) = 4.96, MS, = 0.015. In addition, there was an interaction between presence on the PI task and age, F(\, 62) = 8.40, MS, = 0.015; older adults made more false alarms than young adults for both PI and non-PI items, but the age difference was much larger for PI items (.460 vs. .296) than for non-PI items (.351 vs. .310). In sum, as is usually found, recognition performance was poorer for older adults than for young adults. Also, in Experiment 2, older adults had difficulty in discriminating items that had appeared on the perceptual identification test from completely new distractors, suggesting difficulty in memory for contextual information. This contrasts with the finding in Experiment 1, where no interaction between age and presence on the PI task was observed. Hence, the two studies reported here are inconclusive with respect to the question of whether this type of contextual discrimination is more difficult for older adults. Memory for presentation modality. The conditional probability of correctly identifying the presentation modality of words correctly recognized as being on the study list was computed for each subject for each combination of input modality and PI status. A 2 (previously seen vs. previously heard) x 2 (PI vs. non-PI) x 2 (age) ANOVA produced reliable main effects of input modality, PI status, and age. As is clear from Table 6, auditorily presented items were more often correctly identified as having been heard (.814) than visually presented words were identified as having been seen (.582), F(l, 62) = 47.73, MS, = 0.072. The input modality of items that had not appeared on the PI test was more accurately reported (.716) than was that of items that had appeared on the PI test also (.681), F(l, 62) = 6.28, MSe = 0.012. Young adults were more accurate (.757) than older adults (.640), F(l, 62) = 18.24, MS, = 0.048. Finally, there was an Age x Input Modality interaction, F{\, 62) = 8.39, MS, = 0.072. Young adults were much more accurate in reporting input modality than older adults for previously seen items (.689 vs. .475), F(l, 62) = 22.40, MS, = 0.066; the age difference for previously heard items was negligible (.824 vs. .804) and was not reliable {F < 1). Given the absence of an

Table 5 Proportions and Standard Deviations of Hits and False Alarms in Experiment 2 Non-PI items

PI items Age

Hits—saw Hits—heard FA Hits—saw Hits—heard FA

Young P SD

.887 .137

.887 .113

.296 .196

.883 .117

.865 .124

.310 .193

.830 .460 .843 .863 .862 .171 .211 .147 .184 .140 Note. FA = false alarm; PI = perceptual identification.

.351 .266

Older P SD

Table 6 Conditional Probabilities and Standard Deviations of Correct Modality Judgments in Experiment 2 PI Items

Heard Young .675 .810 Conditional P .189 SD .180 Older .434 .804 Conditional P .213 .197 SD Note. PI = perceptual identification. Age

Saw

Non-PI Items Saw

Heard

.703 .195

.838 .185

.516 .187

.805 .167

interaction between age and presence on the PI task (F< 1), it is not surprising that the main effects of age and input modality and the interaction between these two variables were also found when PI and non-PI items were analyzed separately (all Fs > 4.68). Nor is it surprising that young adults' performance on modality judgments was reliably better than chance (.50) for all combinations of modality and PI status (all ts > 5.26). Older adults' scores, on the other hand, were reliably better than chance for previously heard items (both ts > 8.72); for previously seen items, their scores were reliably lower than chance for PI items (/ = 1.76) and at chance for non-PI items (t