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Response Deadline and Subjective Awareness in Recognition Memory
Consciousness and Cognition 8, 484–496 (1999) Article ID ccog.1999.0409, available online at http://www.idealibrary.com on
Response Deadline and Subjective Awareness in Recognition Memory John M. Gardiner 1 and Cristina Ramponi City University, London, United Kingdom
and Alan Richardson-Klavehn Westminster University, London, United Kingdom Level of processing and generation effects were replicated in separate experiments in which recognition memory was tested using either short (500 ms) or long (1500 ms) response deadlines. These effects were similar at each deadline. Moreover, at each deadline these effects were associated with subsequent reports of remembering, not of knowing. And reports of both knowing and remembering increased following the longer deadline. These results imply that knowing does not index an automatic familiarity process, as conceived in some dual-process models of recognition, and that both remembering and knowing increase with the slower, more controlled processing permitted by the longer response time. 1999 Academic Press
Remember and know responses were introduced by Tulving (1985) as measures of autonoetic and noetic consciousness, which in his theory respectively reflect two different mind/brain systems, episodic and semantic memory. Autonoetic consciousness is characterized by awareness of one’s self in relation to time and place and is expressed in recollective experiences. Noetic consciousness is characterized by awareness of knowledge, including awareness of events, but it does not include recollective experiences of one’s self in relation to time and place. It is expressed in feelings of familiarity or of just knowing. Recognition memory studies that have made use of remember and know responses have established that remembering and knowing can be systematically dissociated from each other and may even be functionally independent. Some variables affect remembering and not knowing. Some variables affect knowing, not remembering. Other variables affect both remembering and knowing in opposite ways. Remembering and knowing have also been found to differ systematically in different subject populations, to be selectively influenced by psychopharmacological agents, and to be associated with differences in electrophysiological measures of neural activation. Such evidence provides compelling support for the existence of the two states of awareness and for the implication that they may reflect different mind/brain systems. For a comprehensive review, see Gardiner and Richardson-Klavehn (in press). Remembering and knowing have also been related to dual-process models of rec1 To whom correspondence and reprint requests should be addressed at Department of Psychology, City University, Northampton Square, London EC1V 0HB, England. E-mail: [email protected]. 484 1053-8100/99 $30.00
Copyright 1999 by Academic Press All rights of reproduction in any form reserved.
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ognition memory which propose that recognition can be accomplished on the basis of two independent processes, a relatively fast, automatic, familiarity process and a relatively slow, more consciously controlled, recollection process (e.g., Jacoby, 1991). These theories assume that the two processes of recollection and familiarity give rise respectively to conscious experiences of recollection and to feelings of familiarity, as measured by remember and know responses (Jacoby, Yonelinas, & Jennings, 1997). The use of remember and know responses differs from tests of dualprocess models primarily in its focus on the actual subjective experiences, rather than on the hypothetical processes. One approach to testing dual-process models of recognition memory makes use of a response-signal procedure in which subjects are trained to make their recognition test decisions at varying intervals following the presentation of test items. For example, Toth (1996) used this procedure with just two intervals, 500 and 1500 ms. How does this manipulation impact on recognition decisions? The logic is that the shorter response deadline does not allow much time for the slower, more controlled recollection process to come into play and that recognition decisions must be based largely on the faster, more automatic familiarity process. In contrast, the longer response deadline allows the slower, more controlled recollection process to come more into play and recognition decisions then will be based largely on that process. One of Toth’s (1996) findings was that a deep compared with a shallow level of processing at study led to improved recognition at the shorter as well as at the longer deadline. There was no significant interaction between level of processing and response deadline, though the effect was somewhat reduced at the shorter deadline (cf. Mulligan & Hirshman, 1995). This finding suggests that familiarity may reflect conceptual, as well as perceptual, automaticity. And Toth provided further support for this conclusion in other experiments, including one in which inclusion/exclusion tasks were used at each deadline so that Jacoby’s (1991) process dissociation procedure could be applied to provide estimates of familiarity and recollection. Evidence of effects of deeper level of processing on the familiarity process contrasts with the general finding that there is no such effect upon the experience of familiarity as measured by know responses (Gardiner, Java, & Richardson-Klavehn, 1996a). However, no previous study has investigated remembering and knowing in conjunction with the response-signal procedure. We describe two experiments in which this was done. Subjects in our experiments were also trained to make their recognition decisions either 500 or 1500 ms after the presentation of the test items. After positive recognition decisions, subjects reported whether they were aware of remembering or of knowing the prior occurrence of the item. In addition, if no such awareness was experienced, subjects were instructed to report that they had been guessing, though they were not encouraged to guess. Indeed, subjects were told to respond as accurately as possible at both response deadlines, in order to avoid any speed–accuracy tradeoff. In addition, in Experiment 1, level of processing was manipulated. The experiment had several goals. The first goal was to replicate the effects of level of processing and response deadline reported by Toth (1996). Deeper conceptual processing, and a longer deadline, should both lead to improved recognition performance, and there should be no interaction between these effects. The second goal
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was to determine how these effects relate to subsequent reports of remembering and knowing. On the basis of Toth’s (1996) findings and dual-process models, one might expect effects of deeper conceptual processing in know responses at the short deadline, if not at the long deadline. And one might expect an interaction such that remembering increases more with response time than knowing. One might also expect more know responses at the short deadline than at the long deadline, if know responses index automaticity of processing. In contrast, on the basis of previous remember– know studies one might expect level of processing effects to be confined to remember responses, even at the short deadline. And there is little reason to expect response deadline to interact with the proportions of remember and know responses. We also predicted that guess responses, unlike remember or know responses, should reveal little or no memory for study list encounters with the words that elicit them. Gardiner and Conway (in press) described a meta-analysis of 40 different experimental conditions in which subjects reported guesses, as well as remembering and knowing. The results of this meta-analysis showed that guesses for studied items, if anything, tended to be lower than guesses for unstudied items, presumably because of reduced response opportunity (see too, e.g., Gardiner et al., 1996a). EXPERIMENT 1
Method Subjects. The subjects were 32 male or female undergraduate students at City University, London. They were either paid for their participation or they were given course credits. They were tested individually. Design and materials. The design was a 2 ⫻ 2 mixed factorial with response deadline (500 vs. 1500 ms) as a between subjects factor and level of processing (semantic vs. phonemic) as a within subject factor. Sixteen subjects were randomly assigned to each response deadline. The materials were 96 common two-syllable words selected from the Toronto word pool. These words were randomly divided into two 48-word study lists, which were counterbalanced across subjects. Within each group, half the subjects received one study list, half the other. Study lists were presented in a fixed random order. In the study phase, subjects performed a semantic orienting task on half the list and a phonemic orienting task on the other half. These tasks were blocked, and their order was counterbalanced within each group. The recognition test consisted of the 96 words from both study lists. The test list was presented in a unique random order for each subject. Following positive decisions in the recognition test, remember, know, or guess responses were required. Prior to the recognition test, subjects were given a lexical decision task in order to train them to respond within a specific time interval (400 ms) following a response signal that occurred either 500 or 1500 ms after each test item was presented. Procedure. Study, training, and test lists were presented on a Macintosh PowerBook computer. Subjects were initially informed only that the experiment involved several different verbal tasks. In the study phase, for the semantic task subjects were told to rate the ease of generating semantic associates of the presented words on a 5-point scale (1 ⫽ very easy; 5 ⫽ very difficult). For the phonemic task subjects
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were told to rate the ease of generating words that rhyme with the presented words, using the same 5-point scale. The study list words were presented in the center of the computer screen for 1 second. Buttons labeled 1 to 5 appeared next to each word and remained on the screen until subjects responded by clicking the appropriate one. These responses were not recorded, though subjects were not aware of that fact. Their responses triggered the presentation of the next word on the screen. In addition to the critical set of studied words, six filler words were presented, three at the beginning of each of the two orienting tasks, to accustom subjects to these tasks. Following the presentation of the study list, subjects were given a similar lexical decision task to that used by Toth (1996), in order to train them with respect to the response-signal procedure. The materials were a set of 40 items, 20 words and 20 nonwords, all four letters long and all pronounceable. These items were presented on the computer screen in a fixed random order and subjects were instructed that they had to decide whether each item was a word, or not, and to make their response at the prescribed times. A set of arrows was shown for 1 s before each word or nonword appeared and in the same location of the screen. A row of asterisks was then presented as the response signal, either 500 or 1500 ms after the test item, depending on the group to which the subject had been assigned. The asterisks appeared a little below the test item, and subjects were told that they had to respond within 400 ms of the appearance of this signal. They responded by pressing one of two buttons on the keyboard, one labeled Yes, indicating that the item was a word, and one labeled No, indicating that it was not. Subjects used the index finger of their left hand for the Yes response and the index finger of their right hand for the No response. The computer recorded the time interval between the appearance of each response signal and the subject’s response. When the subject responded the screen cleared and a dialogue box giving the response time and a verbal message was displayed at the top of the screen. If the response was faster than 50 ms, the message was ‘‘Too fast . . . wait for the asterisks to appear.’’ If the response time was between 50 and 400 ms, the message was ‘‘Good.’’ And if the response time was longer than 400 ms, the message was ‘‘Too slow . . . try to respond faster.’’ Response times and the accompanying messages were displayed for 2 s, and after a 1-s gap, the arrows preceding the presentation of the next test item appeared. In order to further encourage subjects to respond within the appropriate times, they were told that the number of times they managed to stay within those time boundaries would be displayed at the end of the test and that they should aim to achieve the highest possible score. After this training session, subjects were given instructions for the recognition test. They were informed that none of the items in this test had been used in the lexical decision task, but, rather, that they were either words they had rated earlier or words that had not previously appeared. They were told that they now had to decide which words were ones they had seen earlier and that their decisions, and the timing of those responses, would be similar to those in the lexical decision task, except that a Yes response now meant that they recognized the word, and a No response now meant that they did not recognize the word. In other respects, including the provision of feedback on subjects’ response times, subjects were told that the procedure was similar to that in the previous lexical decision task. In addition to this, subjects were told that immediately after the feedback dialogue
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TABLE 1 Proportions of Responses as a Function of Level of Processing and Response Deadline (with Standard Errors of the Means in Parentheses) Studied Response category for each deadline (ms)
Semantic
Phonemic
Unstudied
500
1500
500
1500
500
1500
Remember Know Guess
.43 (.06) .09 (.02) .04 (.01)
.59 (.04) .15 (.03) .03 (.01)
.28 (.06) .10 (.01) .10 (.03)
.32 (.04) .21 (.03) .06 (.02)
.01 (.00) .05 (.01) .06 (.01)
.02 (.01) .07 (.02) .04 (.01)
Overall
.56 (.05)
.77 (.03)
.48 (.05)
.59 (.05)
.12 (.02)
.13 (.02)
box disappeared three other buttons, labeled Remember, Know, or Guess, would appear on the screen if their earlier response had been Yes. They were given the usual instructions regarding the states of awareness appropriate for each of these responses (for a full version of these instructions, see Gardiner & Richardson-Klavehn, in press). Subjects were also discouraged from guessing and told to regard it as a default response, partly in order to try to reduce false alarm rates generally and partly to try to obtain similar false alarm rates for each response deadline. The first 12 words in the recognition test were filler items, to allow subjects to become accustomed to the new decision task. Six of these filler items were the filler words presented in the study lists; the other 6 were similar words. Recognition accuracy for these filler items was not recorded, but subjects were provided with feedback on their response times. After the recognition test, the experimenter arbitrarily selected a few remember, know, and guess responses and asked subjects to describe in more detail their experiences in making those responses, as a further check that they had correctly understood them. Results and Discussion The principal results are summarized in Table 1. Following Toth (1996), responses were included for analysis if they occurred between 50 and 500 ms of the response signal. He considered responses earlier than 50 ms to be anticipatory and responses later than 500 ms to largely reflect conscious recollection. Of a total of 3072 responses, only 282 (or 9%) fell outside these intervals. The pattern of results when all responses are considered did not differ in any important way from the pattern of results when only responses within the time boundaries were considered, so responses outside these boundaries are not discussed further. The responses summarized in Table 1 also show that the instructions that discouraged guessing were quite successful. False alarm rates were generally low, and there was only a trivial difference in the overall false alarm rate between response deadlines (t ⬍ 1). And, as predicted, guess responses to studied compared with unstudied words did not differ much either. So neither false alarms nor guesses were included in the main statistical analyses
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that we describe. The main conclusions we draw are pretty much the same even when those responses are included, as we show later. The major trends in the data summarized in Table 1 are readily apparent. Recognition was enhanced by the deeper level of processing and by the longer response deadline. There was little indication of any interaction between these two effects. Know as well as remember responses increased with the longer deadline. And the level of processing effect was evident only in conjunction with remember responses, even at the short response deadline. This description of the results was borne out by the results of analyses of variance (ANOVAs) carried out on individual subject hit rates for remember and know responses. (Remember and know responses were treated as an additional factor in these analyses because statistical comparisons between these responses are necessary for the conclusions we wish to draw.) The α level was set at .05. Both the main effect of response deadline [F(1, 30) ⫽ 8.48, MSE ⫽ .03] and of level of processing [F(1, 30) ⫽ 35.04, MSE ⫽ .01] were significant. The interaction between response deadline and level of processing was not significant [F(1, 30) ⫽ 1.66, MSE ⫽ .01]. There were more remember than know responses [F(1, 30) ⫽ 47.84, MSE ⫽ .05]. The interaction between response type and response deadline was not significant [F ⬍ 1]. The interaction between response type and level of processing was, however, significant [F(1, 30) ⫽ 29.83, MSE ⫽ .02]. The three-way interaction was nearly but not quite significant [F(1, 30) ⫽ 3.52, MSE ⫽ .02, p ⫽ .07]. This last outcome largely seems to reflect the fact that, following the phonemic compared with the semantic level of processing, the 1500-ms deadline was associated with a somewhat smaller increase in remember responses and a somewhat larger increase in know responses. However, the comparable three-way interaction in Experiment 2 did not approach significance. Thus the experiment replicated Toth’s (1996) results in finding no interaction between level of processing effects and response deadline and extended them by adding the subjective reports. Level of processing was found to influence remembering, rather than knowing, even at the short deadline. And remembering and knowing increased in parallel with response deadline. EXPERIMENT 2
Experiment 2 was designed to replicate Experiment 1, but with generating versus reading study list words taking the place of the level of processing manipulation (see too, e.g., Gardiner et al., 1996a). Generating versus reading arguably provides an even stronger test of the influence of conceptual processing than that provided by a level of processing manipulation. In other respects the two experiments were quite similar, except that a longer retention interval was used in Experiment 2, largely to mitigate against possible ceiling effects. Method Subjects. The subjects were 40 other male or female undergraduate students at City University, London. They were either paid for their participation or they were given course credits. They were tested individually.
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TABLE 2 Proportions of Responses as a Function of Generating versus Reading and Response Deadline (with Standard Errors of the Means in Parentheses) Studied Response category for each deadline (ms)
Generate
Read
Unstudied
500
1500
500
1500
500
1500
Remember Know Guess
.19 (.04) .14 (.03) .03 (.01)
.23 (.04) .22 (.03) .03 (.01)
.08 (.02) .14 (.03) .04 (.01)
.13 (.02) .19 (.02) .05 (.02)
.03 (.01) .09 (.02) .03 (.01)
.02 (.01) .08 (.02) .04 (.01)
Overall
.36 (.05)
.48 (.03)
.26 (.04)
.37 (.04)
.15 (.02)
.14 (.03)
Design and materials. The design was a 2 ⫻ 2 mixed factorial with response deadline (500 vs. 1500 ms) as a between subjects factor and generating versus reading study list words as a within subject factor. Twenty subjects were randomly assigned to each response deadline. The materials consisted of 80 common words that have been used in previous studies (e.g., Java & Gardiner, 1991). For each of these 80 words there was a descriptive phrase which, when presented at study together with the first letter of the word, virtually guaranteed its successful generation. In most essential respects the experimental design was the same as that in Experiment 1, except that subjects either generated the words at study, given a descriptive phrase and initial letter, or read the words, and there was a retention interval of between 3 and 7 days (depending on subject availability) after the study phase, before the lexical decision training task and recognition test. Procedure. The procedure was similar to that of Experiment 1 in all but two respects. First, for the generate and read study tasks, subjects had to say each study list word aloud. In the generate task a descriptive phrase and the initial letter of the word were shown on the computer screen. Examples are: Building in which horses are kept: S; Bird seen in Trafalgar Square: P; Object or area to aim at: T; String of beads used in prayer: R. For the read task the words were presented alone. Presentation of successive items in the study list was controlled manually by the subject, contingent upon his or her having said each word aloud. When subjects failed to generate the word, the experimenter said it. (The incidence of such failures was negligible, and so the data were not conditionalized upon generation success.) The same training session used in Experiment 1 took place when subjects returned to the laboratory, followed by a similar recognition test. However, pilot work indicated that after the longer retention interval in this experiment, subjects were much more inclined to adopt lenient response criteria in making their recognition decisions. In order to discourage this tendency, subjects were told not to press the Yes key unless they were absolutely sure the word had occurred in the study list. Results and Discussion The principal results summarized in Table 2 again refer to responses that occurred between 50 and 500 ms after the response signal. Of a total of 3840 responses, only
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355 (or 9%) fell outside these intervals. The pattern of results when all responses are considered did not differ in any important way from the pattern of results when only responses within the time boundaries were considered, so responses outside these boundaries are not discussed further. The responses summarized in Table 2 also show that the instructions that discouraged guessing were quite successful. False alarm rates were almost as low as those in Experiment 1, and again there was only a trivial difference in the overall false alarm rate between response deadlines (t ⬍ 1). Nor did guess responses to studied and unstudied words differ much. So in this experiment too, neither false alarms nor guesses were included in the main statistical analyses that we describe. The major trends in the data summarized in Table 2 are readily apparent. Recognition was enhanced by generating, compared with reading, and by the longer response deadline. There was little indication of any interaction between these two effects. Know as well as remember responses increased with the longer deadline. And the generation effect was evident only in conjunction with remember responses, even at the short response deadline. In comparison with the results summarized in Table 1, however, it is clear the longer retention interval led to a marked decrease in the number of remember responses, as would be expected from previous findings (Gardiner & Java, 1991). An ANOVA was carried out on individual subject hit rates for remember and know responses summarized in Table 2. Both the main effect of response deadline [F(1, 38) ⫽ 6.06, MSE ⫽ .02] and of generating versus reading [F(1, 38) ⫽ 12.75, MSE ⫽ .01] were significant. The interaction between response deadline and generating versus reading was not significant [F ⬍ 1]. There were no more remember than know responses [F ⬍ 1]. The interaction between response type and response deadline was not significant [F ⬍ 1]. The interaction between response type and generating versus reading was, however, significant [F(1, 38) ⫽ 5.45, MSE ⫽ .02]. There was no threeway interaction [F ⬍ 1]. GENERAL DISCUSSION
Each of these two experiments replicate Toth’s (1996) finding that deeper conceptual processing at study enhances recognition performance at the short as well as at the long response deadline. They also replicate the finding that recognition performance generally increases with the longer deadline and the finding that there was no interaction between these two effects. Given the assumption that the short response deadline compels recognition decisions to be based largely on a more automatic familiarity process, then these findings can be interpreted as evidence that the more automatic familiarity process, as well as the more controlled recollection process, is influenced by conceptual processing. The facilitatory effects of conceptual processing on the faster, more automatic recognition decisions did not, however, influence experiences of familiarity as measured directly by know responses. Effects of conceptual processing were apparent only in remember responses. Moreover, know responses, as well as remember responses, increased with longer compared with shorter response deadlines. Granted that with a long deadline slower more controlled processing can be brought more
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into play, then it seems that knowing, as well as remembering, increases with increasing control. Conversely, granted that with a short deadline processing is more automatic, then it seems that remembering, as well as knowing, may be triggered relatively automatically. The finding of low numbers of know responses at the short response deadline runs counter to the expectation that at this deadline there might have been a relatively high incidence of these responses. But it raises the possibility that the absence of any effects of deeper conceptual processing on know responses might be related to scale attenuation. We think this unlikely, however. In an additional median split analysis, for the short response deadline only, we reanalyzed data from the 8 subjects with know hit rates above the median know hit rate in Experiment 1 and from the 10 subjects with know hit rates above the median know hit rate in Experiment 2. Averaged over all 18 subjects, the mean know hit rate for the deeper conceptual processing conditions was .19 and for the shallower conceptual processing conditions it was .18. These know hit rates are virtually identical (t ⬍ 1). Moreover they are quite similar to the know hit rates observed for all subjects at the longer response deadlines. Nor was the overall pattern of results much changed in Experiment 2, compared with Experiment 1, despite the very different numbers of remember responses in each experiment. Our findings support the conclusion that remembering and knowing do not correspond with recollection and familiarity processes as conceived in some dual-process theories. This conclusion holds good not just at an experiential level but also if the familiarity process is estimated by the independence remember–know model discussed by Jacoby et al. (1997; see too, e.g., Jacoby, Jones, & Dolan, 1998). In this model familiarity is estimated by dividing the proportion of correct know responses by one minus the proportion of correct remember responses. Calculated from the aggregate scores summarized in Tables 1 and 2, at the short deadline this model gives familiarity estimates of .16 and .14, for the semantic and phonemic tasks in Experiment 1, and familiarity estimates of .17 and .15, for the generate and read tasks in Experiment 2. The corresponding estimates for the longer deadline are .37 and .31, in Experiment 1, and .29 and .22, in Experiment 2. Thus, if anything, familiarity estimates show larger effects of conceptual processing at the longer deadline. Moreover, these estimates show that the familiarity process increases with the longer deadline and does so to a greater extent than the recollection process, which in this model is given simply by the proportion of correct remember responses, as shown in Tables 1 and 2. But we do not think these familiarity estimates are legitimate and, in marked contrast, Toth’s (1996) estimates of familiarity from the process dissociation procedure showed large effects of conceptual processing and little effect of response deadline. The difference between results from the two procedures no doubt reflects their different focus on actual subjective experiences and on hypothetical processes. Because of this, even with an independence assumption remember and know responses may not provide an appropriate source of evidence for testing this dual-process model. That does not constitute evidence against the model, so far as the hypothetical processes are concerned. It does constitute evidence against its ability to account for experiences of remembering and knowing and the claim that the independence
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FIG. 1. Recognition memory ROCs plotted in z space for (going from left to right) remembering, remembering plus knowing, and remembering plus knowing and guessing.
remember–know model leads to converging estimates with respect to the familiarity process (for more discussion, see Richardson-Klavehn, Gardiner, & Java, 1996). It is instructive also to look at our data from the standpoint of a trace strength account in which remember, know, and guess responses are treated as three increasingly lenient response criteria (e.g., Donaldson, 1996; Hirshman & Master, 1997). Figure 1 shows receiver operating characteristics (ROCs) plotted in z space separately for each experiment. They are based on the cumulative proportions of remember, remember plus know, and remember plus know and guess responses shown in Tables 1 and 2. These cumulative proportions were then transformed to z scores and plotted with normal deviates. As can be seen, the resulting plots were quite linear, as they should be according to this signal detection model. They support our main empirical
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conclusions by showing strong effects of response deadline and of conceptual processing, which essentially had additive effects, particularly in Experiment 2. However, apart from the tendency toward some deviation in Experiment 1, the plots are not only linear but also parallel. If a faster familiarity process were indeed contributing disproportionately to the more automatic responses at the short response deadline the slopes should increase more sharply with that deadline than with the long deadline. This is because the familiarity process is closely identified with the more lenient criteria, which include know responses. Not only do the plots fail to show this pattern, if anything, in Experiment 1 they tend to show the reverse pattern. We use these plots merely to illustrate that our conclusions largely hold even when the data are looked at from this alternative perspective and do not mean to imply that we view a criteria-based account of the subjective states of awareness as a viable theory. There are other considerations and other data that present considerable difficulties for such a theory. These include its lack of explanatory value (see, e.g., Gardiner, Ramponi, & Richardson-Klavehn, 1998) and the fact that, both at the level of meta-analyses of many experimental conditions and at the level of individual subjects, tests of the model show that know responses generally, if not always, reflect an additional source of memory (see Gardiner & Conway, in press; Gardiner & Gregg, 1997). Indeed, in concluding a recent review of the literature we suggested that neither the kind of dual-process model that we have been primarily concerned with in the present experiments nor a single trace-strength model can provide an adequate account of remembering and knowing (Gardiner & Richardson-Klavehn, in press). A few other caveats are in order. One concerns the timing of the subjective reports. The response buttons for those judgments appeared immediately after the feedback dialogue box disappeared from the screen. Subjects then had immediately to click on the appropriate button. The time interval between the recognition decision and the appearance of the response buttons labeled ‘‘remember,’’ ‘‘know,’’ or ‘‘guess’’ was exactly the same in the short and long response deadline conditions. It is possible that some phenomenal experiences may have come to mind in the brief interval between the recognition decision and the time subjects clicked the appropriate subjective report button. But it seems unlikely that that would have happened to any significant extent, and it could have happened at the long as well as at the short response deadlines and with knowing as well as with remembering. This sequence of responses—recognition decision followed by subjective report—defines the most commonly used remember/know paradigm (though see Hicks and Marsh, 1999). Remember and know judgments in the present experiments were no less and no more retrospective than usual. We believe that even at the short response deadline the subjective reports largely corresponded with subjective awareness at the time of the recognition decision. Even if they had not, the dual-process model still leads one to expect the kinds of outcome we described—that there should be relatively more know responses following the shorter response deadline, for example, and that those know responses should show effects of the conceptual variables. It still remains the case that there is a theoretical problem with the claim that such a model can account for remembering and knowing. Another caveat concerns the possible role of the different amounts of time for
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which test words were displayed at the two response deadlines. This procedure was adopted in order to duplicate the procedure used to obtain the effects of response deadline and conceptual processing that we were trying to replicate. We cannot discount the possibility that the patterns of remember, know, and guess responses might in part have been influenced by the difference in the time the test words remained visible, above and beyond any effects of the response deadline. But we can think of no reason why they should. A further problem that might be addressed in subsequent research concerns the possibility that under other circumstances the tendency toward an interaction between conceptual processing and response deadline in Experiment 1 might become significant (see, too, Mulligan & Hirshman, 1995). We discounted that possible interaction largely because there was clearly no such interaction in Experiment 2. But it is also possible that the very different retention intervals involved across the two experiments may be important, as suggested when comparing the top and bottom plots shown in Figure 1. There are two final comments. First, our findings are also of interest because only one other independent variable has been found to lead to a parallel increase in remembering and knowing. That variable is repeated study trials, compared with a single study trial, with excerpts from highly unfamiliar folk music (Gardiner, Kaminska, Dixon, & Java, 1996b; Gardiner & Radomski, 1999). Evidence of associations between remembering and knowing completes the fourfold pattern of outcomes needed to establish that they are not merely dissociable states of awareness, but functionally independent. Second, Dewhurst and Conway (1994) measured response latency for recognition decisions and correlated those latencies with subsequent reports of remembering and knowing. Their results converge nicely with ours. They found that the shortest response latencies were those associated with remembering rather than with knowing. From their data too the implication is that remembering may be relatively automatic, as well as more controlled. Our conclusion is that remembering and knowing do not correspond with the distinction between consciously controlled and automatic processes, as conceived in some dual-process models of recognition. The subjective states of awareness seem more orthogonal to that process distinction than identifiable with it. ACKNOWLEDGMENTS This research was supported by Grant 000236225 from the Economic and Social Research Council (ESRC) of Great Britain and we thank them for their support. We also thank Mark Baldwin, Vernon Gregg, Stephen Lindsay, and two anonymous reviewers for their comments on earlier versions of the paper. And we are grateful to William Banks for suggesting the ROC plots and pointing out their relevance to our conclusions.
REFERENCES Dewhurst, S. A., & Conway, M. A. (1994). Pictures, images, and recollective experience. Journal of Experimental Psychology: Learning, Memory, and Cognition, 20, 1088–1098. Donaldson, W. (1996). The role of decision processes in remembering and knowing. Memory and Cognition, 24, 523–533. Gardiner, J. M., & Conway, M. A. Levels of awareness and varieties of experience. In B. H. Challis &
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B. M. Velichovsky (Eds.), Stratification of consciousness and cognition. Amsterdam: Benjamin. [in press] Gardiner, J. M., & Gregg, V. H. (1997). Recognition memory with little or no remembering: Implications for a detection model. Psychonomic Bulletin and Review, 4, 474–479. Gardiner, J. M., & Java, R. I. (1991). Forgetting in recognition memory with and without recollective experience. Memory and Cognition, 19, 617–623. Gardiner, J. M., Java, R. I., & Richardson-Klavehn, A. (1996a). How level of processing really influences awareness in recognition memory. Canadian Journal of Experimental Psychology, 50, 114–122. Gardiner, J. M., Kaminska, Z., Dixon, M., & Java, R. I. (1996b). Repetition of previously novel melodies sometimes increases both remember and know responses in recognition memory. Psychonomic Bulletin and Review, 3, 366–371. Gardiner, J. M., & Radomski, E. (1999). Awareness of recognition memory for Polish and English folk songs in Polish and English folk. Memory, 7, 461–470. Gardiner, J. M., Ramponi, C., & Richardson-Klavehn, A. (1998). Experiences of remembering, knowing, and guessing. Consciousness and Cognition, 7, 1–26. Gardiner, J. M., & Richardson-Klavehn, A. Remembering and knowing. In E. Tulving & F. I. M. Craik (Eds.), Handbook of memory. New York: Oxford Univ. Press. [in press] Hicks, J. L., & Marsh, R. L. (1999). Remember-know judgments can depend on how memory is tested. Psychonomic Bulletin and Review, 6, 117–122. Hirshman, E., & Master, S. (1997). Modeling the conscious correlates of recognition memory: Reflections on the remember-how paradigm. Memory and Cognition, 24, 345–351. Jacoby, L. L. (1991). A process-dissociation framework: Separating automatic from intentional uses of memory. Journal of Memory and Language, 30, 513–541. Jacoby, L. L., Jones, T. C., & Dolan, P. O. (1998). Two effects of repetition: Support for a dual-process model of know judgements and exclusion errors. Psychonomic Bulletin and Review, 5, 705–709. Jacoby, L. L., Yonelinas, A. P., & Jennings, J. M. (1997). The relation between conscious and unconscious (automatic) influences: A declaration of independence. In J. D. Cohen & J. W. Schooler (Eds.), Scientific approaches to the question of consciousness (pp. 13–47). Hillsdale: Erlbaum. Java, R. I., & Gardiner, J. M. (1991). Priming and aging: Further evidence of preserved memory function. American Journal of Psychology, 104, 89–100. Mulligan, N., & Hirshman, E. (1995). Speed-accuracy trade-offs and the dual process model of recognition memory. Journal of Memory and Language, 34, 1–18. Richardson-Klavehn, A., Gardiner, J. M., & Java, R. I. (1996). Memory: Task dissociations, process dissociations, and dissociations of consciousness. In G. Underwood (Ed.), Implicit cognition (pp. 85–158). Oxford: Oxford Univ. Press. Toth, J. P. (1996). Conceptual automaticity in recognition memory: Levels-of-processing effects on familiarity. Canadian Journal of Experimental Psychology, 50, 123–138. Tulving, E. (1985). Memory and consciousness. Canadian Psychologist, 26, 1–12. Received July 29, 1998
Response Deadline and Subjective Awareness in Recognition Memory John M. Gardiner 1 and Cristina Ramponi City University, London, United Kingdom
and Alan Richardson-Klavehn Westminster University, London, United Kingdom Level of processing and generation effects were replicated in separate experiments in which recognition memory was tested using either short (500 ms) or long (1500 ms) response deadlines. These effects were similar at each deadline. Moreover, at each deadline these effects were associated with subsequent reports of remembering, not of knowing. And reports of both knowing and remembering increased following the longer deadline. These results imply that knowing does not index an automatic familiarity process, as conceived in some dual-process models of recognition, and that both remembering and knowing increase with the slower, more controlled processing permitted by the longer response time. 1999 Academic Press
Remember and know responses were introduced by Tulving (1985) as measures of autonoetic and noetic consciousness, which in his theory respectively reflect two different mind/brain systems, episodic and semantic memory. Autonoetic consciousness is characterized by awareness of one’s self in relation to time and place and is expressed in recollective experiences. Noetic consciousness is characterized by awareness of knowledge, including awareness of events, but it does not include recollective experiences of one’s self in relation to time and place. It is expressed in feelings of familiarity or of just knowing. Recognition memory studies that have made use of remember and know responses have established that remembering and knowing can be systematically dissociated from each other and may even be functionally independent. Some variables affect remembering and not knowing. Some variables affect knowing, not remembering. Other variables affect both remembering and knowing in opposite ways. Remembering and knowing have also been found to differ systematically in different subject populations, to be selectively influenced by psychopharmacological agents, and to be associated with differences in electrophysiological measures of neural activation. Such evidence provides compelling support for the existence of the two states of awareness and for the implication that they may reflect different mind/brain systems. For a comprehensive review, see Gardiner and Richardson-Klavehn (in press). Remembering and knowing have also been related to dual-process models of rec1 To whom correspondence and reprint requests should be addressed at Department of Psychology, City University, Northampton Square, London EC1V 0HB, England. E-mail: [email protected]. 484 1053-8100/99 $30.00
Copyright 1999 by Academic Press All rights of reproduction in any form reserved.
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ognition memory which propose that recognition can be accomplished on the basis of two independent processes, a relatively fast, automatic, familiarity process and a relatively slow, more consciously controlled, recollection process (e.g., Jacoby, 1991). These theories assume that the two processes of recollection and familiarity give rise respectively to conscious experiences of recollection and to feelings of familiarity, as measured by remember and know responses (Jacoby, Yonelinas, & Jennings, 1997). The use of remember and know responses differs from tests of dualprocess models primarily in its focus on the actual subjective experiences, rather than on the hypothetical processes. One approach to testing dual-process models of recognition memory makes use of a response-signal procedure in which subjects are trained to make their recognition test decisions at varying intervals following the presentation of test items. For example, Toth (1996) used this procedure with just two intervals, 500 and 1500 ms. How does this manipulation impact on recognition decisions? The logic is that the shorter response deadline does not allow much time for the slower, more controlled recollection process to come into play and that recognition decisions must be based largely on the faster, more automatic familiarity process. In contrast, the longer response deadline allows the slower, more controlled recollection process to come more into play and recognition decisions then will be based largely on that process. One of Toth’s (1996) findings was that a deep compared with a shallow level of processing at study led to improved recognition at the shorter as well as at the longer deadline. There was no significant interaction between level of processing and response deadline, though the effect was somewhat reduced at the shorter deadline (cf. Mulligan & Hirshman, 1995). This finding suggests that familiarity may reflect conceptual, as well as perceptual, automaticity. And Toth provided further support for this conclusion in other experiments, including one in which inclusion/exclusion tasks were used at each deadline so that Jacoby’s (1991) process dissociation procedure could be applied to provide estimates of familiarity and recollection. Evidence of effects of deeper level of processing on the familiarity process contrasts with the general finding that there is no such effect upon the experience of familiarity as measured by know responses (Gardiner, Java, & Richardson-Klavehn, 1996a). However, no previous study has investigated remembering and knowing in conjunction with the response-signal procedure. We describe two experiments in which this was done. Subjects in our experiments were also trained to make their recognition decisions either 500 or 1500 ms after the presentation of the test items. After positive recognition decisions, subjects reported whether they were aware of remembering or of knowing the prior occurrence of the item. In addition, if no such awareness was experienced, subjects were instructed to report that they had been guessing, though they were not encouraged to guess. Indeed, subjects were told to respond as accurately as possible at both response deadlines, in order to avoid any speed–accuracy tradeoff. In addition, in Experiment 1, level of processing was manipulated. The experiment had several goals. The first goal was to replicate the effects of level of processing and response deadline reported by Toth (1996). Deeper conceptual processing, and a longer deadline, should both lead to improved recognition performance, and there should be no interaction between these effects. The second goal
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was to determine how these effects relate to subsequent reports of remembering and knowing. On the basis of Toth’s (1996) findings and dual-process models, one might expect effects of deeper conceptual processing in know responses at the short deadline, if not at the long deadline. And one might expect an interaction such that remembering increases more with response time than knowing. One might also expect more know responses at the short deadline than at the long deadline, if know responses index automaticity of processing. In contrast, on the basis of previous remember– know studies one might expect level of processing effects to be confined to remember responses, even at the short deadline. And there is little reason to expect response deadline to interact with the proportions of remember and know responses. We also predicted that guess responses, unlike remember or know responses, should reveal little or no memory for study list encounters with the words that elicit them. Gardiner and Conway (in press) described a meta-analysis of 40 different experimental conditions in which subjects reported guesses, as well as remembering and knowing. The results of this meta-analysis showed that guesses for studied items, if anything, tended to be lower than guesses for unstudied items, presumably because of reduced response opportunity (see too, e.g., Gardiner et al., 1996a). EXPERIMENT 1
Method Subjects. The subjects were 32 male or female undergraduate students at City University, London. They were either paid for their participation or they were given course credits. They were tested individually. Design and materials. The design was a 2 ⫻ 2 mixed factorial with response deadline (500 vs. 1500 ms) as a between subjects factor and level of processing (semantic vs. phonemic) as a within subject factor. Sixteen subjects were randomly assigned to each response deadline. The materials were 96 common two-syllable words selected from the Toronto word pool. These words were randomly divided into two 48-word study lists, which were counterbalanced across subjects. Within each group, half the subjects received one study list, half the other. Study lists were presented in a fixed random order. In the study phase, subjects performed a semantic orienting task on half the list and a phonemic orienting task on the other half. These tasks were blocked, and their order was counterbalanced within each group. The recognition test consisted of the 96 words from both study lists. The test list was presented in a unique random order for each subject. Following positive decisions in the recognition test, remember, know, or guess responses were required. Prior to the recognition test, subjects were given a lexical decision task in order to train them to respond within a specific time interval (400 ms) following a response signal that occurred either 500 or 1500 ms after each test item was presented. Procedure. Study, training, and test lists were presented on a Macintosh PowerBook computer. Subjects were initially informed only that the experiment involved several different verbal tasks. In the study phase, for the semantic task subjects were told to rate the ease of generating semantic associates of the presented words on a 5-point scale (1 ⫽ very easy; 5 ⫽ very difficult). For the phonemic task subjects
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were told to rate the ease of generating words that rhyme with the presented words, using the same 5-point scale. The study list words were presented in the center of the computer screen for 1 second. Buttons labeled 1 to 5 appeared next to each word and remained on the screen until subjects responded by clicking the appropriate one. These responses were not recorded, though subjects were not aware of that fact. Their responses triggered the presentation of the next word on the screen. In addition to the critical set of studied words, six filler words were presented, three at the beginning of each of the two orienting tasks, to accustom subjects to these tasks. Following the presentation of the study list, subjects were given a similar lexical decision task to that used by Toth (1996), in order to train them with respect to the response-signal procedure. The materials were a set of 40 items, 20 words and 20 nonwords, all four letters long and all pronounceable. These items were presented on the computer screen in a fixed random order and subjects were instructed that they had to decide whether each item was a word, or not, and to make their response at the prescribed times. A set of arrows was shown for 1 s before each word or nonword appeared and in the same location of the screen. A row of asterisks was then presented as the response signal, either 500 or 1500 ms after the test item, depending on the group to which the subject had been assigned. The asterisks appeared a little below the test item, and subjects were told that they had to respond within 400 ms of the appearance of this signal. They responded by pressing one of two buttons on the keyboard, one labeled Yes, indicating that the item was a word, and one labeled No, indicating that it was not. Subjects used the index finger of their left hand for the Yes response and the index finger of their right hand for the No response. The computer recorded the time interval between the appearance of each response signal and the subject’s response. When the subject responded the screen cleared and a dialogue box giving the response time and a verbal message was displayed at the top of the screen. If the response was faster than 50 ms, the message was ‘‘Too fast . . . wait for the asterisks to appear.’’ If the response time was between 50 and 400 ms, the message was ‘‘Good.’’ And if the response time was longer than 400 ms, the message was ‘‘Too slow . . . try to respond faster.’’ Response times and the accompanying messages were displayed for 2 s, and after a 1-s gap, the arrows preceding the presentation of the next test item appeared. In order to further encourage subjects to respond within the appropriate times, they were told that the number of times they managed to stay within those time boundaries would be displayed at the end of the test and that they should aim to achieve the highest possible score. After this training session, subjects were given instructions for the recognition test. They were informed that none of the items in this test had been used in the lexical decision task, but, rather, that they were either words they had rated earlier or words that had not previously appeared. They were told that they now had to decide which words were ones they had seen earlier and that their decisions, and the timing of those responses, would be similar to those in the lexical decision task, except that a Yes response now meant that they recognized the word, and a No response now meant that they did not recognize the word. In other respects, including the provision of feedback on subjects’ response times, subjects were told that the procedure was similar to that in the previous lexical decision task. In addition to this, subjects were told that immediately after the feedback dialogue
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TABLE 1 Proportions of Responses as a Function of Level of Processing and Response Deadline (with Standard Errors of the Means in Parentheses) Studied Response category for each deadline (ms)
Semantic
Phonemic
Unstudied
500
1500
500
1500
500
1500
Remember Know Guess
.43 (.06) .09 (.02) .04 (.01)
.59 (.04) .15 (.03) .03 (.01)
.28 (.06) .10 (.01) .10 (.03)
.32 (.04) .21 (.03) .06 (.02)
.01 (.00) .05 (.01) .06 (.01)
.02 (.01) .07 (.02) .04 (.01)
Overall
.56 (.05)
.77 (.03)
.48 (.05)
.59 (.05)
.12 (.02)
.13 (.02)
box disappeared three other buttons, labeled Remember, Know, or Guess, would appear on the screen if their earlier response had been Yes. They were given the usual instructions regarding the states of awareness appropriate for each of these responses (for a full version of these instructions, see Gardiner & Richardson-Klavehn, in press). Subjects were also discouraged from guessing and told to regard it as a default response, partly in order to try to reduce false alarm rates generally and partly to try to obtain similar false alarm rates for each response deadline. The first 12 words in the recognition test were filler items, to allow subjects to become accustomed to the new decision task. Six of these filler items were the filler words presented in the study lists; the other 6 were similar words. Recognition accuracy for these filler items was not recorded, but subjects were provided with feedback on their response times. After the recognition test, the experimenter arbitrarily selected a few remember, know, and guess responses and asked subjects to describe in more detail their experiences in making those responses, as a further check that they had correctly understood them. Results and Discussion The principal results are summarized in Table 1. Following Toth (1996), responses were included for analysis if they occurred between 50 and 500 ms of the response signal. He considered responses earlier than 50 ms to be anticipatory and responses later than 500 ms to largely reflect conscious recollection. Of a total of 3072 responses, only 282 (or 9%) fell outside these intervals. The pattern of results when all responses are considered did not differ in any important way from the pattern of results when only responses within the time boundaries were considered, so responses outside these boundaries are not discussed further. The responses summarized in Table 1 also show that the instructions that discouraged guessing were quite successful. False alarm rates were generally low, and there was only a trivial difference in the overall false alarm rate between response deadlines (t ⬍ 1). And, as predicted, guess responses to studied compared with unstudied words did not differ much either. So neither false alarms nor guesses were included in the main statistical analyses
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that we describe. The main conclusions we draw are pretty much the same even when those responses are included, as we show later. The major trends in the data summarized in Table 1 are readily apparent. Recognition was enhanced by the deeper level of processing and by the longer response deadline. There was little indication of any interaction between these two effects. Know as well as remember responses increased with the longer deadline. And the level of processing effect was evident only in conjunction with remember responses, even at the short response deadline. This description of the results was borne out by the results of analyses of variance (ANOVAs) carried out on individual subject hit rates for remember and know responses. (Remember and know responses were treated as an additional factor in these analyses because statistical comparisons between these responses are necessary for the conclusions we wish to draw.) The α level was set at .05. Both the main effect of response deadline [F(1, 30) ⫽ 8.48, MSE ⫽ .03] and of level of processing [F(1, 30) ⫽ 35.04, MSE ⫽ .01] were significant. The interaction between response deadline and level of processing was not significant [F(1, 30) ⫽ 1.66, MSE ⫽ .01]. There were more remember than know responses [F(1, 30) ⫽ 47.84, MSE ⫽ .05]. The interaction between response type and response deadline was not significant [F ⬍ 1]. The interaction between response type and level of processing was, however, significant [F(1, 30) ⫽ 29.83, MSE ⫽ .02]. The three-way interaction was nearly but not quite significant [F(1, 30) ⫽ 3.52, MSE ⫽ .02, p ⫽ .07]. This last outcome largely seems to reflect the fact that, following the phonemic compared with the semantic level of processing, the 1500-ms deadline was associated with a somewhat smaller increase in remember responses and a somewhat larger increase in know responses. However, the comparable three-way interaction in Experiment 2 did not approach significance. Thus the experiment replicated Toth’s (1996) results in finding no interaction between level of processing effects and response deadline and extended them by adding the subjective reports. Level of processing was found to influence remembering, rather than knowing, even at the short deadline. And remembering and knowing increased in parallel with response deadline. EXPERIMENT 2
Experiment 2 was designed to replicate Experiment 1, but with generating versus reading study list words taking the place of the level of processing manipulation (see too, e.g., Gardiner et al., 1996a). Generating versus reading arguably provides an even stronger test of the influence of conceptual processing than that provided by a level of processing manipulation. In other respects the two experiments were quite similar, except that a longer retention interval was used in Experiment 2, largely to mitigate against possible ceiling effects. Method Subjects. The subjects were 40 other male or female undergraduate students at City University, London. They were either paid for their participation or they were given course credits. They were tested individually.
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TABLE 2 Proportions of Responses as a Function of Generating versus Reading and Response Deadline (with Standard Errors of the Means in Parentheses) Studied Response category for each deadline (ms)
Generate
Read
Unstudied
500
1500
500
1500
500
1500
Remember Know Guess
.19 (.04) .14 (.03) .03 (.01)
.23 (.04) .22 (.03) .03 (.01)
.08 (.02) .14 (.03) .04 (.01)
.13 (.02) .19 (.02) .05 (.02)
.03 (.01) .09 (.02) .03 (.01)
.02 (.01) .08 (.02) .04 (.01)
Overall
.36 (.05)
.48 (.03)
.26 (.04)
.37 (.04)
.15 (.02)
.14 (.03)
Design and materials. The design was a 2 ⫻ 2 mixed factorial with response deadline (500 vs. 1500 ms) as a between subjects factor and generating versus reading study list words as a within subject factor. Twenty subjects were randomly assigned to each response deadline. The materials consisted of 80 common words that have been used in previous studies (e.g., Java & Gardiner, 1991). For each of these 80 words there was a descriptive phrase which, when presented at study together with the first letter of the word, virtually guaranteed its successful generation. In most essential respects the experimental design was the same as that in Experiment 1, except that subjects either generated the words at study, given a descriptive phrase and initial letter, or read the words, and there was a retention interval of between 3 and 7 days (depending on subject availability) after the study phase, before the lexical decision training task and recognition test. Procedure. The procedure was similar to that of Experiment 1 in all but two respects. First, for the generate and read study tasks, subjects had to say each study list word aloud. In the generate task a descriptive phrase and the initial letter of the word were shown on the computer screen. Examples are: Building in which horses are kept: S; Bird seen in Trafalgar Square: P; Object or area to aim at: T; String of beads used in prayer: R. For the read task the words were presented alone. Presentation of successive items in the study list was controlled manually by the subject, contingent upon his or her having said each word aloud. When subjects failed to generate the word, the experimenter said it. (The incidence of such failures was negligible, and so the data were not conditionalized upon generation success.) The same training session used in Experiment 1 took place when subjects returned to the laboratory, followed by a similar recognition test. However, pilot work indicated that after the longer retention interval in this experiment, subjects were much more inclined to adopt lenient response criteria in making their recognition decisions. In order to discourage this tendency, subjects were told not to press the Yes key unless they were absolutely sure the word had occurred in the study list. Results and Discussion The principal results summarized in Table 2 again refer to responses that occurred between 50 and 500 ms after the response signal. Of a total of 3840 responses, only
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355 (or 9%) fell outside these intervals. The pattern of results when all responses are considered did not differ in any important way from the pattern of results when only responses within the time boundaries were considered, so responses outside these boundaries are not discussed further. The responses summarized in Table 2 also show that the instructions that discouraged guessing were quite successful. False alarm rates were almost as low as those in Experiment 1, and again there was only a trivial difference in the overall false alarm rate between response deadlines (t ⬍ 1). Nor did guess responses to studied and unstudied words differ much. So in this experiment too, neither false alarms nor guesses were included in the main statistical analyses that we describe. The major trends in the data summarized in Table 2 are readily apparent. Recognition was enhanced by generating, compared with reading, and by the longer response deadline. There was little indication of any interaction between these two effects. Know as well as remember responses increased with the longer deadline. And the generation effect was evident only in conjunction with remember responses, even at the short response deadline. In comparison with the results summarized in Table 1, however, it is clear the longer retention interval led to a marked decrease in the number of remember responses, as would be expected from previous findings (Gardiner & Java, 1991). An ANOVA was carried out on individual subject hit rates for remember and know responses summarized in Table 2. Both the main effect of response deadline [F(1, 38) ⫽ 6.06, MSE ⫽ .02] and of generating versus reading [F(1, 38) ⫽ 12.75, MSE ⫽ .01] were significant. The interaction between response deadline and generating versus reading was not significant [F ⬍ 1]. There were no more remember than know responses [F ⬍ 1]. The interaction between response type and response deadline was not significant [F ⬍ 1]. The interaction between response type and generating versus reading was, however, significant [F(1, 38) ⫽ 5.45, MSE ⫽ .02]. There was no threeway interaction [F ⬍ 1]. GENERAL DISCUSSION
Each of these two experiments replicate Toth’s (1996) finding that deeper conceptual processing at study enhances recognition performance at the short as well as at the long response deadline. They also replicate the finding that recognition performance generally increases with the longer deadline and the finding that there was no interaction between these two effects. Given the assumption that the short response deadline compels recognition decisions to be based largely on a more automatic familiarity process, then these findings can be interpreted as evidence that the more automatic familiarity process, as well as the more controlled recollection process, is influenced by conceptual processing. The facilitatory effects of conceptual processing on the faster, more automatic recognition decisions did not, however, influence experiences of familiarity as measured directly by know responses. Effects of conceptual processing were apparent only in remember responses. Moreover, know responses, as well as remember responses, increased with longer compared with shorter response deadlines. Granted that with a long deadline slower more controlled processing can be brought more
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into play, then it seems that knowing, as well as remembering, increases with increasing control. Conversely, granted that with a short deadline processing is more automatic, then it seems that remembering, as well as knowing, may be triggered relatively automatically. The finding of low numbers of know responses at the short response deadline runs counter to the expectation that at this deadline there might have been a relatively high incidence of these responses. But it raises the possibility that the absence of any effects of deeper conceptual processing on know responses might be related to scale attenuation. We think this unlikely, however. In an additional median split analysis, for the short response deadline only, we reanalyzed data from the 8 subjects with know hit rates above the median know hit rate in Experiment 1 and from the 10 subjects with know hit rates above the median know hit rate in Experiment 2. Averaged over all 18 subjects, the mean know hit rate for the deeper conceptual processing conditions was .19 and for the shallower conceptual processing conditions it was .18. These know hit rates are virtually identical (t ⬍ 1). Moreover they are quite similar to the know hit rates observed for all subjects at the longer response deadlines. Nor was the overall pattern of results much changed in Experiment 2, compared with Experiment 1, despite the very different numbers of remember responses in each experiment. Our findings support the conclusion that remembering and knowing do not correspond with recollection and familiarity processes as conceived in some dual-process theories. This conclusion holds good not just at an experiential level but also if the familiarity process is estimated by the independence remember–know model discussed by Jacoby et al. (1997; see too, e.g., Jacoby, Jones, & Dolan, 1998). In this model familiarity is estimated by dividing the proportion of correct know responses by one minus the proportion of correct remember responses. Calculated from the aggregate scores summarized in Tables 1 and 2, at the short deadline this model gives familiarity estimates of .16 and .14, for the semantic and phonemic tasks in Experiment 1, and familiarity estimates of .17 and .15, for the generate and read tasks in Experiment 2. The corresponding estimates for the longer deadline are .37 and .31, in Experiment 1, and .29 and .22, in Experiment 2. Thus, if anything, familiarity estimates show larger effects of conceptual processing at the longer deadline. Moreover, these estimates show that the familiarity process increases with the longer deadline and does so to a greater extent than the recollection process, which in this model is given simply by the proportion of correct remember responses, as shown in Tables 1 and 2. But we do not think these familiarity estimates are legitimate and, in marked contrast, Toth’s (1996) estimates of familiarity from the process dissociation procedure showed large effects of conceptual processing and little effect of response deadline. The difference between results from the two procedures no doubt reflects their different focus on actual subjective experiences and on hypothetical processes. Because of this, even with an independence assumption remember and know responses may not provide an appropriate source of evidence for testing this dual-process model. That does not constitute evidence against the model, so far as the hypothetical processes are concerned. It does constitute evidence against its ability to account for experiences of remembering and knowing and the claim that the independence
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FIG. 1. Recognition memory ROCs plotted in z space for (going from left to right) remembering, remembering plus knowing, and remembering plus knowing and guessing.
remember–know model leads to converging estimates with respect to the familiarity process (for more discussion, see Richardson-Klavehn, Gardiner, & Java, 1996). It is instructive also to look at our data from the standpoint of a trace strength account in which remember, know, and guess responses are treated as three increasingly lenient response criteria (e.g., Donaldson, 1996; Hirshman & Master, 1997). Figure 1 shows receiver operating characteristics (ROCs) plotted in z space separately for each experiment. They are based on the cumulative proportions of remember, remember plus know, and remember plus know and guess responses shown in Tables 1 and 2. These cumulative proportions were then transformed to z scores and plotted with normal deviates. As can be seen, the resulting plots were quite linear, as they should be according to this signal detection model. They support our main empirical
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conclusions by showing strong effects of response deadline and of conceptual processing, which essentially had additive effects, particularly in Experiment 2. However, apart from the tendency toward some deviation in Experiment 1, the plots are not only linear but also parallel. If a faster familiarity process were indeed contributing disproportionately to the more automatic responses at the short response deadline the slopes should increase more sharply with that deadline than with the long deadline. This is because the familiarity process is closely identified with the more lenient criteria, which include know responses. Not only do the plots fail to show this pattern, if anything, in Experiment 1 they tend to show the reverse pattern. We use these plots merely to illustrate that our conclusions largely hold even when the data are looked at from this alternative perspective and do not mean to imply that we view a criteria-based account of the subjective states of awareness as a viable theory. There are other considerations and other data that present considerable difficulties for such a theory. These include its lack of explanatory value (see, e.g., Gardiner, Ramponi, & Richardson-Klavehn, 1998) and the fact that, both at the level of meta-analyses of many experimental conditions and at the level of individual subjects, tests of the model show that know responses generally, if not always, reflect an additional source of memory (see Gardiner & Conway, in press; Gardiner & Gregg, 1997). Indeed, in concluding a recent review of the literature we suggested that neither the kind of dual-process model that we have been primarily concerned with in the present experiments nor a single trace-strength model can provide an adequate account of remembering and knowing (Gardiner & Richardson-Klavehn, in press). A few other caveats are in order. One concerns the timing of the subjective reports. The response buttons for those judgments appeared immediately after the feedback dialogue box disappeared from the screen. Subjects then had immediately to click on the appropriate button. The time interval between the recognition decision and the appearance of the response buttons labeled ‘‘remember,’’ ‘‘know,’’ or ‘‘guess’’ was exactly the same in the short and long response deadline conditions. It is possible that some phenomenal experiences may have come to mind in the brief interval between the recognition decision and the time subjects clicked the appropriate subjective report button. But it seems unlikely that that would have happened to any significant extent, and it could have happened at the long as well as at the short response deadlines and with knowing as well as with remembering. This sequence of responses—recognition decision followed by subjective report—defines the most commonly used remember/know paradigm (though see Hicks and Marsh, 1999). Remember and know judgments in the present experiments were no less and no more retrospective than usual. We believe that even at the short response deadline the subjective reports largely corresponded with subjective awareness at the time of the recognition decision. Even if they had not, the dual-process model still leads one to expect the kinds of outcome we described—that there should be relatively more know responses following the shorter response deadline, for example, and that those know responses should show effects of the conceptual variables. It still remains the case that there is a theoretical problem with the claim that such a model can account for remembering and knowing. Another caveat concerns the possible role of the different amounts of time for
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which test words were displayed at the two response deadlines. This procedure was adopted in order to duplicate the procedure used to obtain the effects of response deadline and conceptual processing that we were trying to replicate. We cannot discount the possibility that the patterns of remember, know, and guess responses might in part have been influenced by the difference in the time the test words remained visible, above and beyond any effects of the response deadline. But we can think of no reason why they should. A further problem that might be addressed in subsequent research concerns the possibility that under other circumstances the tendency toward an interaction between conceptual processing and response deadline in Experiment 1 might become significant (see, too, Mulligan & Hirshman, 1995). We discounted that possible interaction largely because there was clearly no such interaction in Experiment 2. But it is also possible that the very different retention intervals involved across the two experiments may be important, as suggested when comparing the top and bottom plots shown in Figure 1. There are two final comments. First, our findings are also of interest because only one other independent variable has been found to lead to a parallel increase in remembering and knowing. That variable is repeated study trials, compared with a single study trial, with excerpts from highly unfamiliar folk music (Gardiner, Kaminska, Dixon, & Java, 1996b; Gardiner & Radomski, 1999). Evidence of associations between remembering and knowing completes the fourfold pattern of outcomes needed to establish that they are not merely dissociable states of awareness, but functionally independent. Second, Dewhurst and Conway (1994) measured response latency for recognition decisions and correlated those latencies with subsequent reports of remembering and knowing. Their results converge nicely with ours. They found that the shortest response latencies were those associated with remembering rather than with knowing. From their data too the implication is that remembering may be relatively automatic, as well as more controlled. Our conclusion is that remembering and knowing do not correspond with the distinction between consciously controlled and automatic processes, as conceived in some dual-process models of recognition. The subjective states of awareness seem more orthogonal to that process distinction than identifiable with it. ACKNOWLEDGMENTS This research was supported by Grant 000236225 from the Economic and Social Research Council (ESRC) of Great Britain and we thank them for their support. We also thank Mark Baldwin, Vernon Gregg, Stephen Lindsay, and two anonymous reviewers for their comments on earlier versions of the paper. And we are grateful to William Banks for suggesting the ROC plots and pointing out their relevance to our conclusions.
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