The mnemonic mechanisms of errorless learning

Neuropsychologia 44 (2006) 2806–2813

The mnemonic mechanisms of errorless learning Nicole D. Anderson a,b,c,∗ , Fergus I.M. Craik c,d a

Kunin-Lunenfeld Applied Research Unit, Baycrest, 3560 Bathurst Street, Toronto, Ont. M6A 2E1, Canada b Department of Medicine (Psychiatry), University of Toronto, Canada c Department of Psychology, University of Toronto, Canada d Rotman Research Institute, Baycrest, Canada Received 10 November 2005; received in revised form 13 April 2006; accepted 22 May 2006 Available online 9 August 2006

Abstract Errorless learning enhances memory relative to errorful, trial-and-error learning, but the extent to which this advantage relies on implicit or explicit memory processes is not clear. Previous attempts to determine the mnemonic mechanisms of errorless learning have relied on contrasts between patient groups or between tasks, but both approaches are problematic. In this study, healthy younger and older adults were engaged in errorless or errorful learning using a process dissociation procedure that provides separate estimates of explicit recollection and implicit familiarity within-subjects and within-task (Hay & Jacoby, 1996). Consistent with much prior research, we found an age-related decrement in recollection, but age-invariance in familiarity. In the young adults, errorless learning reduced the misleading familiarity of prior errors, but this benefit was offset by the non-elaborative nature of the errorless learning condition that also reduced recollection. In the older adults, who are less able to oppose familiaritybased errors because of their lower recollection, errorless learning only reduced the misleading impact of previous errors. Our results support Baddeley and Wilson’s (1994) position that the errorless learning effect is mediated by implicit memory processes: individuals with reduced explicit memory benefit from errorless learning because errorless learning bypasses the need to engage explicit error elimination processes. We do not recommend standard errorless learning for individuals with intact explicit memory, such as students trying to learn information in preparation for an examination. © 2006 Elsevier Ltd. All rights reserved. Keywords: Errorless learning; Aging; Memory; Explicit memory; Implicit memory; Process dissociation procedure

Errorless learning is a technique wherein individuals are prevented from making errors when initially learning information. This technique, originally devised within the animal learning field (Terrace, 1963), was first applied to the rehabilitation of memory impairments by Baddeley and Wilson (1994). Their study compared the effects of errorful and errorless learning in a group of amnestic individuals and younger and older healthy control participants. In errorful learning, participants were told, for example, “I am thinking of a five-letter word that begins with QU”. Participants then generated up to three errors before being told the correct word that they were to remember. In the errorless condition, participants were told, for example, “I am thinking of a five-letter word that begins with QU and it is QUOTE”. Baddeley and Wilson found that in the amnestic participants, subsequent learning and memory was more successful if the initial learning experience was errorless rather than errorful. The

∗

Corresponding author. Tel.: +1 416 785 2500x3366; fax: +1 416 785 4295. E-mail address: [email protected] (N.D. Anderson).

0028-3932/$ – see front matter © 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.neuropsychologia.2006.05.026

same general pattern was found for the older control participants, but the data were limited by ceiling effects in both control groups. Similar benefits of errorless learning in the amnestic patient KC using a different paradigm were reported by Hayman, Macdonald, and Tulving (1993). The benefit of errorless learning for memory-impaired individuals has since been replicated many times, in people with brain injury (Hayman et al., 1993; Komatsu, Mimura, Kato, Wakamatsu, & Kashima, 2000; McKenna & Gerhand, 2002; Parkin, Hunkin, & Squires, 1998; Tailby & Haslam, 2003; Wilson, Baddeley, Evans, & Shiel, 1994), Alzheimer’s disease (Clare, Wilson, Carter, Roth, & Hodges, 2002), and schizophrenia (O’Carroll, Russell, Lawrie, & Johnstone, 1999). Moreover, the technique has been applied broadly, for example to train word processing skills (Hunkin, Squires, Aldrich, & Parkin, 1998), proper names (Parkin et al., 1998), and face-name associations (Clare et al., 2002; Kalla, Downes, & Van den Broek, 2001). The cognitive mechanisms of the errorless learning effect are debated. Some argue for a role of implicit memory. For example, Baddeley and Wilson (1994) proposed that implicit memory is

N.D. Anderson, F.I.M. Craik / Neuropsychologia 44 (2006) 2806–2813

unable to eliminate strong incorrect competing responses, and hence amnestic individuals, who rely mainly on implicit memory, benefit from the prevention of errors during learning (see also Evans et al., 2000). Others, however, argue that explicit memory is responsible for the errorless learning effect. Hunkin, Squires, Parkin, and Tidy (1998) compared indirect word fragment completion and direct cued recall performance after errorless or errorful learning in a group of amnestic brain-injured individuals. They found an advantage for errorless learning in free recall, a task that arguably relies heavily on explicit memory, but no difference between the learning conditions for word fragment completion, a task that relies mainly on implicit memory. Hunkin et al. concluded that explicit memory, however limited in brain-injured populations, benefits from the prevention of errors during learning (see also Tailby & Haslam, 2003, for a similar approach and conclusion). These previous attempts to determine whether the errorless learning effect is mediated by implicit or explicit memory suffer because they address the question indirectly. As pointed out by many (e.g., Evans et al., 2000; Hunkin, Squires, Parkin, et al., 1998), even patients with severe amnesia typically have some degree of residual explicit memory. Similarly, neither direct nor indirect tests of memory are process-pure (Jacoby, Toth, & Yonelinas, 1993)—there is involvement of implicit memory on direct tests (e.g., “‘dog’ just feels right so I am going to say it” in a free recall test), and involvement of explicit memory in indirect tests, an effect that has been called “explicit contamination”. Hence, using either subject groups or memory tests to disentangle the contributions of explicit and implicit memory to errorless learning is problematic. Our goal was to explore the mnemonic mechanisms of errorless learning more directly. To this end, we used the habit paradigm developed by Hay and Jacoby (1996). This paradigm uses a process dissociation procedure (Jacoby, 1991) that pits implicit and explicit memory against each other within a task. We agree with Jacoby (1991) that the terms “explicit” and “implicit”, meant to relate to memory processes, have become too entangled with particular memory tests (e.g., recall and word stem completion, respectively), and hence prefer the terms “recollection” and “familiarity” to refer to the intentional and unintentional (respectively) memory processes that are involved during both explicit and implicit memory. In Hay and Jacoby’s (1999) paradigm, familiarity-based memory habits were created in a training phase of the study, and then episodic memory was explored for a list of items that were either congruent or incongruent with the habits. More specifically, in the training phase participants were presented with a word and a stem of an associated word (e.g., “knee-b n ”) and participants guessed what the second word was before it was presented. These pairs were made either “typical” by being presented on 75% of the trials (e.g., “knee-bend”) or “atypical” by being presented on 25% of the trials (e.g., “knee-bone”). In the subsequent episodic memory phase, participants were presented with short lists of word pairs to study that were either typical or atypical, and were then given the first word from each pair and asked to recall the second word. When participants studied typical word pairs, correct recall of the typical response word

2807

could be mediated either by recollection (R) or by familiarity (F), as both would lead to a correct response (thus R or F). However, when participants studied atypical word pairs, they would provide the (incorrect) typical response word only if recollection for the immediately preceding study list had failed and they were relying on the familiarity-based memory habit developed in the first phase of the study (F alone). Hence, an estimate of recollection (R) is derived from the probability of a correct typical response on typical trials (R or F) minus the probability of an erroneous typical response on atypical trials (F alone). An estimate of familiarity (F) is then computed by dividing the probability of an incorrect typical response to atypical word pairs by 1-R (Jacoby, 1991). Hay and Jacoby (1996, 1999) reported that manipulating the strength of the habit by changing the percentage of typical trials during training affected familiarity but not recollection, whereas normal aging, faster presentation rates, and shorter response deadlines affected recollection but not familiarity. These dissociations support the view that recollection and familiarity make independent contributions to memory performance within a task. The Hay and Jacoby (1996, 1999) paradigm is an errorful learning paradigm, in that participants were made to guess during the training phase, and given that the atypical pair was presented on some of the trials, errors were common. We therefore replicated their paradigm as an errorful learning condition but also added a second errorless learning condition in which the word pairs were shown in full on each trial, thereby eliminating errors. Because any differences between the errorful and errorless conditions could be attributed to participants not attending in the errorless condition (because they were not required to make any response), we added a third errorless condition in which the word pairs were also shown in full on each trial, but participants were asked to read each response word out loud.1 We tested healthy younger and healthy older adults with the aims of replicating the common pattern of an age-related decrement in recollection but age invariance of familiarity (see Jacoby, Jennings, & Hay, 1996), and exploring the mnemonic mechanisms of errorless learning. Recollection always leads to a correct response, but the accuracy of memories that are mediated by familiarity depends on the situation. In the current experiment, reliance on familiarity with the typical responses established in the training phase leads to correct responses for typical pairs, but it also leads to errors for atypical pairs. In general, when recollection and familiarity are in conflict, performance will improve to the extent that one uses recollection to oppose the misleading effects of familiarity. If errorless learning eliminates the implicit influence of prior errors on current learning and memory, as Baddeley and Wilson (1994) contended, then in an opposition paradigm as used in this study estimates of familiarity should be lower following errorless than errorful learning (i.e., fewer erroneous typical responses should be emitted). If errorless learning facilitates explicit memory, as Hunkin, Squires, Aldrich, et al. (1998) and Hunkin, Squires, Parkin, et al.

1 We thank an anonymous reviewer on an earlier version of this manuscript for this suggestion.

2808

N.D. Anderson, F.I.M. Craik / Neuropsychologia 44 (2006) 2806–2813

Table 1 Participant demographic data Group

Condition

Age

Education

Mill Hill

Digit symbol

M

S.D.

M

S.D.

M

S.D.

M

S.D.

Young

Errorful (n = 24) Errorless (n = 24) Errorless-speak (n = 12)

21.0 21.1 20.9

3.3 3.2 2.7

14.8 14.9 15.2

2.2 2.6 2.3

18.5 17.2 18.8

3.3 4.5 3.9

93.0 90.2 96.2

12.0 10.2 15.0

Old

Errorful (n = 26) Errorless (n = 26) Errorless-speak (n = 12)

73.6 75.9 74.3

6.0 5.5 5.1

15.2 14.7 16.5

3.3 3.6 2.7

21.6 20.6 23.6

5.0 5.2 4.6

58.4 57.4 61.7

12.2 9.4 15.4

(1998) argued, then estimates of recollection should be higher following errorless than errorful learning. There is reason to believe, however, that errorless learning may not be beneficial for memory in all cases (cf. Evans et al., 2000). Errorful learning requires participants to generate target memoranda when given an associated cue, whereas errorless learning is entirely passive. We know from much previous research with healthy adults that elaborative processing and generating to-be-remembered material improve later memory performance (Craik & Tulving, 1975; Slamecka & Graf, 1978) and are associated with large increases in recollection and smaller but reliable increases in familiarity (for a review see Yonelinas, 2002). Hence, recollection and familiarity may in fact be higher following errorful than errorless learning. 1. Method 1.1. Participants Sixty younger adults and 64 healthy older adults volunteered to participate. Twenty-four younger adults and 26 older adults were assigned to each of the errorful and errorless conditions, and an additional 12 participants in each age group participated in the errorless-speak condition (see procedure). Participants were recruited from volunteer research participant pools or responded to flyers posted at the university, and were paid for their participation or received course credit. Age and years of formal education did not differ between learning conditions within age group and the education level did not differ between younger and older adults (all p > 0.28, see Table 1). Consistent with prior research comparing younger and older adults, vocabulary scores were higher in the older than younger group, t(122) = 4.34, p < 0.001, whereas digit symbol performance was better in the younger than older group, t(122) = 15.94, p < 0.001. Vocabulary and digit symbol scores did not differ between conditions for either age group (all ps > 0.23). This study was approved by the Research Ethics Boards at the University of Toronto and Baycrest.

1.2. Materials, design, and procedure The materials were from Hay and Jacoby (1996), and consisted of 16 nouns, each paired with two associates that completed the same word fragment (e.g., bend/bone for knee-b n and farm/yard for barn- ar ). One associate for each homograph was assigned to Set A, and the other to Set B. Participants were tested individually using an IBM-compatible laptop (15 in. screen) running Presentation software Version 0.76. Words were presented in the middle of a white screen in black lowercase Times New Roman letters, with each letter approximately 15 × 10 mm in size. Participants were seated approximately 75 cm from the screen. Participants first completed the Mill Hill vocabulary test and then the memory task. The training phase and study-test phase procedures are illustrated in Fig. 1. The errorful condition proceeded much as described by Hay and Jacoby (1999).

In the training phase, participants were presented with a stimulus-word fragment pair (e.g., knee-b n ), and were instructed to guess the response word. Participants had 2 s to respond (verbally) and then the correct response word for that trial was presented for 1 s, followed by a blank screen inter-stimulus interval (ISI) for 500 ms. The Errorless condition proceeded in a similar way, except that the complete stimulus-response pair was shown in full for 3 s on each trial, followed by a blank screen ISI for 500 ms. The Errorless-speak condition was identical to the errorless condition, except that participants were instructed to read the response words out loud. The response words from one of the sets (A or B) were shown on 75% of the trials (“typical” pairs), and the response words from the other set were shown on the remaining 25% of the trials (“atypical” pairs). Set assignment to typical and atypical pairs was counterbalanced across participants. Participants were instructed to pay attention to the responses that were presented, that more than one response word would appear for each stimulus word, and that some response words would appear more often than others. The examiner recorded responses. The training phase consisted of three consecutive blocks of 128 trials, with each stimulus word presented eight times in each block with six typical and two atypical response words. The order of the items within each block was random, with the restriction that the same stimulus word was not presented more than three times in a row. The entire training phase lasted approximately 25 min. After training, participants completed 16 successive study-test lists divided into two halves of eight lists. Each study list comprised eight word pairs from the training phase—six typical and two atypical, maintaining the response probabilities from the training phase. Participants in the errorful condition were again presented with the stimulus-word fragment pair and were instructed to guess the response word within 2 s and then the correct response word for that trial was shown for 1 s. Participants in the Errorless condition were shown the complete word pair for 3 s; the study phase proceeded the same way in the errorless-speak condition, except participants were asked to read the response words aloud. After each study list, a random number between 30 and 100 appeared on the screen for 1 s, followed by a blank screen for 6.5 s, and participants were instructed to count backwards by threes from the presented number until the test list began. Each test list consisted of eight stimulus-word fragment pairs corresponding to studied items and participants were instructed to supply the response word from the immediately preceding study list. Participants were warned that each test list would also contain pairs from the training phase that were not presented in the study list (two unstudied pairs were presented in each test list),2 and for these items, participants were to supply the first word that came to mind. Participants in both conditions were given 3 s to respond and the examiner again recorded the responses. Test pairs were followed by a 550 ms ISI. Each typical pair was tested six times (three times in each half of the test phase), each atypical pair was tested twice (once in each half of the test phase), and each unstudied pair appeared twice (once in each half of the test phase). No stimulus word was used more than once within a study-test list. The digit symbol task was administered in between the two halves of the test phase. The entire study-test phase lasted approximately 25 min. 2 Each pair was meant to appear as an unstudied pair twice in the study-test phase, once in each half, but due to a programming error the two unstudied pairs were selected randomly (without replacement for that list) from the items that were not in the current study list.

N.D. Anderson, F.I.M. Craik / Neuropsychologia 44 (2006) 2806–2813

2809

Fig. 1. Schematic description of the training and study-test phase procedures. In the training phase and study phase for the errorful group, participants saw a stimulus word and an associated word fragment and have 2 s to guess what the target word was, and then the correct target was shown beside the cue word for 1 s. In the training phase and study phase for the errorless groups, participants were shown the correct full word pair for that trial for 3 s. In the test phases in all conditions, participants saw a cue word and an associated word fragment and had 3 s to recall the response word that was presented in the immediately preceding study list or provide the first word that came to mind.

2. Results An alpha level of 0.05 was used for all statistical tests, and significant effects were decomposed using Sidak post hoc comparisons. 2.1. Training data The training data were analyzed using 2 × 3 repeated measures ANOVAs, with Age group between-subjects and Block within-subjects. Note that training data are available only from the participants in the errorful condition, as participants in the errorless condition made no response during this phase of the study. Participants provided either the typical or the atypical response on the majority of trials, particularly by the second block (see Fig. 2), but did occasionally provide another response

Fig. 2. Mean probability of providing a typical (white bars) or atypical (hatched bars) response in each block of the training phase (±1 S.E.M.).

2810

N.D. Anderson, F.I.M. Craik / Neuropsychologia 44 (2006) 2806–2813

or failed to respond. The probability of providing either the typical or the atypical response was higher in the younger than older adults, F(1, 48) = 17.86, and increased across blocks, F(2, 96) = 162.90, particularly for the older adults, F(2, 96) = 11.98. The probability of providing a typical response did not differ overall between younger and older adults, F(1, 48) < 1, but increased across blocks, F(2, 96) = 35.50, and this increase was particularly marked for the older adults from Blocks 1 to 2 (age group × Block interaction), F(2, 96) = 11.37. The probability of providing an atypical response was greater in the younger than older adults, F(1, 48) = 13.80, and increased from blocks 1 to 2, F(2, 96) = 4.17, marginally more so for younger than older adults (age group × Block interaction), F(2, 96) = 3.15, p = 0.05. 2.2. Study-test data The probability of providing a typical response in the studytest phase, given that the test item was a typical studied pair, an atypical studied pair, or unstudied pair is shown in Fig. 3. These data were first analyzed using a 2 × 3 × 3 repeated measures ANOVA, with Age group and learning condition betweensubjects factors and test item type a within-subjects factor. All effects were significant at p < 0.05. To help decompose these interactions, separate 2 × 3 ANOVAs were conducted within each pair type. The probability of providing a (correct) typical response for typical study pairs (Fig. 3; panel A) was higher in younger than older adults, F(1, 118) = 28.83, and higher in the errorful than in the two errorless conditions (which did not differ from each other), F(2, 118) = 28.35, with no interaction between age group and learning condition, F(2, 118) < 1. The probability of providing an (erroneous) typical response for atypical study pairs (Fig. 3; panel B) was higher in older than younger adults, F(1, 118) = 48.77, and there was an interaction between age group and learning condition, F(2, 118) = 4.76, as younger adults provided comparable proportions of typical responses in the three learning conditions, F(2, 57) = 1.12 (n.s.), whereas older adults provided more erroneous typical responses in the errorful than in the errorless conditions, F(2, 61) = 4.50. The probability of providing a typical response for unstudied pairs (Fig. 3; panel C) was only affected by the learning condition, being higher following errorful than errorless learning, whether or not the response words were read aloud, F(2, 118) = 18.74 (other Fs < 1). Participants provided either the typical or the atypical response on the majority of the trials (M = 0.97–0.99); hence, the comparable analyses of atypical responses provided mirror image results. 2.3. Recollection and familiarity

Fig. 3. Mean probability of providing a typical response to typical word pairs (panel A), atypical word pairs (panel B) and unstudied word pairs (panel C) in the study-test phase (±1 S.E.M.).

Table 2 Estimates of recollection and familiarity Age group

Estimates of recollection and familiarity are shown in Table 2 and were analyzed in separate 2 × 3 ANOVAs, with age group and learning condition between-subjects factors. Recollection was higher in younger than older adults, F(1, 118) = 77.09, and was higher after errorful than errorless learning overall, F(2, 118) = 4.30, but the effects of Age group and Learning condition interacted, F(2, 118) = 3.37. This is because recollection was higher after errorful than errorless learning for the younger

Condition

Recollection

Familiarity

M

S.D.

M

S.D.

Young

Errorful Errorless Errorless-speak

0.62 0.49 0.41

0.19 0.16 0.19

0.70 0.64 0.62

0.20 0.09 0.13

Old

Errorful Errorless Errorless-speak

0.23 0.24 0.20

0.18 0.15 0.10

0.76 0.63 0.60

0.11 0.09 0.16

N.D. Anderson, F.I.M. Craik / Neuropsychologia 44 (2006) 2806–2813

adults, F(2, 57) = 6.34, but not for older adults, F(2, 61) < 1. Familiarity was greater following errorful than errorless learning, F(2, 118) = 9.84, but did not differ between Age groups in either condition. 3. Discussion Our goal was to explore the independent contributions of explicit and implicit memory processes to errorless learning in healthy younger and older adults, using a process dissociation procedure (Hay & Jacoby, 1996, 1999). We found that estimates of (explicit) recollection were reduced in the older group relative to their younger counterparts, whereas estimates of (implicit) familiarity did not differ between the two age groups, consistent with much previous research (e.g., Hay & Jacoby, 1999; Jennings & Jacoby, 1997). The current study also revealed a dissociation between the mnemonic mechanisms underlying errorless learning in younger and older adults. In younger adults, errorless learning reduced both recollection and familiarity, whereas in older adults, it only reduced familiarity. Hence for both groups, errorless learning reduced the misleading, automatic influence of prior errors. This was also seen in the responses to unstudied pairs. The training phase was designed to create a memory habit such that participants would guess the typical response on 75% of trials. In the errorful condition this was clearly achieved, as younger and older participants provided typical responses to unstudied pairs on 76 and 77% of trials, respectively.3 However, errorless learning lead to a weaker memory habit (64 and 63% for the younger and older adults, respectively). The reductions in familiarity and habit strength as a function of errorless learning are consistent with Baddeley and Wilson’s (1994) claim that errorless learning works through implicit memory. Moreover, the effects of errorless learning on familiarity and habit strength cannot be explained by a failure to attend to the word pairs during training: participants in the errorless-speak condition were required to read the response words aloud, yet their performance did not differ from that of participants in the standard errorless learning condition. For the younger adults, however, errorless learning was associated with an additional reduction in recollection. We know from other research that the more a person is engaged in elaborative, semantic processing of memoranda, the better the memory (e.g., Craik & Tulving, 1975; Slamecka & Graf, 1978). Indeed, Tailby and Haslam (2003) recently demonstrated that the errorless learning advantage is amplified if participants engaged in more active encoding strategies. Similarly, Rodriguez-Fornells, Kofidis, and M¨unte (2004) reported that recognition hit rates were higher for words studied in an errorful than errorless learning condition, and also suggested that the requirement to guess the target information leads to deeper levels of processing. The fact that generating a semantic associate in the errorful condition increased recollection only for the younger adults suggests that

3

This match between actual and observed probabilities of a typical response is all the more interesting given the fact that the allocation of word pairs to unstudied items was not balanced as intended (see footnote 2).

2811

the older adults were relying more on automatic, familiaritybased processes during errorful learning. That is, although the probabilities of providing a typical response during the training phase were similar for younger and older adults, the mnemonic mechanisms may have differed for the two age groups: errorful training appears to have built stronger memory habits and recollections in younger adults, whereas it built only stronger memory habits in the older adults. This idea that errorful, or feedbackbased, learning can occur either via implicit or explicit processes is consistent with other research (e. g., Shohamy et al., 2004). As described in the introduction, the memorial advantage of errorless learning has been shown in many studies (see Kessels & De Haan, 2003, for a review). In the current study, errorless learning was actually less beneficial than errorful learning when correctly recalling highly probable items (i.e., typical word pairs). However, for the older adults errorless learning did reduce the number of errors made when recalling less probable items (i.e., atypical word pairs). In a paradigm such as that used in the current study, recollection and familiarity are placed in opposition with one another, and hence the optimal strategy would be to rely on recollection to oppose the misleading influence of familiarity. The older adults showed the typical age-related reduction in recollection relative to the younger adults, and hence were less adept at using recollection to suppress incorrect familiaritybased responses (cf. Baddeley & Wilson, 1995; Jennings & Jacoby, 1997). The reduction in the strength of activation of the typical responses caused by errorless learning hence reduced their likelihood of being emitted, leading to lower estimates of familiarity following errorless than errorful learning conditions. It should also be pointed out that the current paradigm differs from prior errorless learning paradigms in that it involved probabilistic learning. On some trials a particular response was correct, whereas on other trials a different response was correct. We used this paradigm because it fostered a large proportion of errors during learning. It will be important in future studies to explore whether the current findings hold in paradigms in which the correct response is invariant across learning trials. It would be interesting to use a remember-know paradigm (Gardiner & Richardson-Klavehn, 2000; Tulving, 1985) to explore the effects of errorless learning on recollection and familiarity. In this paradigm, a list of items could be presented at study, in one or multiple study trials under conditions of errorless or errorful learning, and then in a recognition task, participants would indicate whether each item is new, remembered from the study list along with specific details from the encoding context, or whether they simply know the item was on the study list but cannot recollect the actual encoding event. Estimates of recollection and familiarity can be derived from this paradigm (Jacoby, Yonelinas, & Jennings, 1997). Hence, learning would be non-probabilistic, given that the “correct” answer would not change from trial to trial. Nevertheless, given the current results, we would expect the errorless learning advantage to be mediated by familiarity, rather than recollection. Moreover, in a remember-know paradigm, recollection and familiarity are not in opposition but rather work in concert supporting correct responses. There would be no penalty for relying on familiarity in this case, because either process would lead to correct

2812

N.D. Anderson, F.I.M. Craik / Neuropsychologia 44 (2006) 2806–2813

responses for studied items, and hence, errorless learning may well increase estimates of familiarity. Kessels, Te Boekhorst, and Postma (2005) recently reported another process dissociation study of errorless and errorful learning in younger and older adults in a spatial memory task. Their study involved a single learning trial, in which participants were either shown (errorless learning) or guessed (errorful learning) the location of objects in a scene. This was followed by an Inclusion memory task in which participants were to place the object in the target location and an Exclusion memory task in which participants were to place the object in an incorrect location. Recollection or familiarity would lead participants to place objects in the target location on the Inclusion task, but only familiarity, in the absence of recollection, would result in erroneous placement of objects in the target location on the exclusion task. Kessels et al. (2005) reported lower recollection in older than younger adults, but no age-related differences in familiarity, the same age-related pattern that was found in the current study. However, in their study errorless learning affected recollection but not familiarity, and did so only for the younger adults such that recollection estimates were higher in errorless than errorful learning. There are a few potential explanations why the current results and those of Kessels et al. diverge. First, some have argued that the different task instructions for Inclusion and Exclusion confuse participants and can lead to different levels of response bias (Curran & Hintzman, 1995; Graf & Komatsu, 1994). One advantage of the current paradigm over the inclusion/exclusion paradigm is that estimates of recollection and familiarity are obtained within a single task and using a single set of instructions. Second, it is unclear how many errors were actually made during errorful learning in Kessels et al.’s study: if subject selected the correct object location, the next trial was presented. In our study, younger and older adults both made mean totals of 178 erroneous guesses during learning (out of 384 trials). Third, participants made fewer errors on the exclusion task in the study by Kessels et al. than in our comparable condition (i.e., typical responses to atypical study pairs): roughly 12 and 16% for the younger and older adults in their study versus 29 and 60% in the current study. Low error rates pose problems for estimating familiarity within participants, and indeed Kessels et al. were unable to estimate familiarity for nine of their participants, a problem that was not encountered in the current study. The underestimation of familiarity estimates in their study would have limited their chances of observing an effect of errorless learning on implicit memory processes. Nevertheless, there remains the possibility that in some circumstances, the errorless learning effect is not only mediated through familiarity, as was found in the current study, but also increases conscious recollection, as reported by Kessels et al. This will have to be explored in future studies. In summary, the current study demonstrated an age-related difference in the mnemonic mechanisms of errorless learning. For both age groups, errorless learning reduced the misleading effects of prior errors. Errorless learning is effective for individuals with explicit memory deficits (e.g., older adults, people with amnesia or Alzheimer’s disease) because their ability to oppose the misleading influence of prior errors is reduced, and errorless

learning reduces the implicit activation of these errors. However, errorless learning also reduced recollection in the younger adults. Standard errorless learning methods may not be ideal for individuals with intact explicit memory processes (e.g., in education settings to help students prepare for exams) because these methods under-utilize self-initiated, elaborative processes. The key to successful memory rehabilitation for all groups may be to design encoding environments that are error-free (thereby reducing the misleading familiarity of errors), but nonetheless require people to engage in elaborative processing (thereby increasing recollection). Acknowledgments We are grateful to Samy Arita, Cherylyn Dickson, and Sharyn Krueger for data collection, to Kyla MacKay for data checking, to Jimmy Shen for computer programming, to Janine M. Hay for sharing her stimuli, and to Larry L. Jacoby for his advice on the design of this experiment. This work was supported by an operating grant (RGPIN 238361-03) from the Natural Sciences and Engineering Council of Canada awarded to the first author. References Baddeley, A., & Wilson, B. A. (1994). When implicit learning fails: Amnesia and the problem of error elimination. Neuropsychologia, 32(1), 53–68. Clare, L., Wilson, B. A., Carter, G., Roth, I., & Hodges, J. R. (2002). Relearning face-name associations in early Alzheimer’s disease. Neuropsychology, 16(4), 538–547. Craik, F. I. M., & Tulving, E. (1975). Depth of processing and the retention of words in episodic memory. Journal of Experimental Psychology: General, 104(3), 268–294. Curran, T., & Hintzman, D. L. (1995). Violations of the independence assumption in process dissociation. Journal of Experimental Psychology: Learning, Memory, and Cognition, 21, 531–547. Evans, J. J., Wilson, B. A., Schuri, U., Andrade, J., Baddeley, A., Bruna, O., et al. (2000). A comparison of “errorless” and “trial-and-error” learning methods for teaching individuals with acquired memory deficits. Neuropsychological Rehabilitation, 10(1), 67–101. Gardiner, J. M., & Richardson-Klavehn, A. (2000). Remembering and knowing. In E. Tulving & F. I. M. Craik (Eds.), The Oxford handbook of memory (pp. 229–244). Oxford: Oxford University Press. Graf, P., & Komatsu, S. (1994). Process dissociation procedure: Handle with caution!. European Journal of Cognitive Psychology, 6, 113–129. Hay, J. F., & Jacoby, L. L. (1996). Separating habit and recollection: Memory slips, process dissociations, and probability matching. Journal of Experimental Psychology: Learning, Memory, and Cognition, 22, 1323–1335. Hay, J. F., & Jacoby, L. L. (1999). Separating habit and recollection in young and older adults: Effects of elaborative processing and distinctivness. Psychology and Aging, 14(1), 122–134. Hayman, C. A. G., Macdonald, C. A., & Tulving, E. (1993). The role of repetition and associative interference in new semantic learning in amnesia: A case experiment. Journal of Cognitive Neuroscience, 5(4), 375–389. Hunkin, N. M., Squires, E. J., Aldrich, F. K., & Parkin, A. J. (1998). Errorless learning and the acquisition of word processing skills. Neuropsychological Rehabilitation, 8(4), 433–449. Hunkin, N. M., Squires, E. J., Parkin, A. J., & Tidy, J. A. (1998). Are the benefits of errorless learning dependent on implicit memory? Neuropsychologia, 36(1), 25–36. Jacoby, L. L. (1991). A process dissociation framework: Separating automatic from intentional uses of memory. Journal of Memory and Language, 30, 513–541.

N.D. Anderson, F.I.M. Craik / Neuropsychologia 44 (2006) 2806–2813 Jacoby, L. L., Jennings, J. M., & Hay, J. F. (1996). Dissociating automatic and consciously controlled processes: Implications for diagnosis and rehabilitation of memory deficits. In D. Herrmann, C. McEvoy, C. Hertzog, P. Hertel, & M. K. Johnson (Eds.), Basic and applied memory research: Theory in context: Vol. 1, (pp. 161–193). Mahwah, NJ: Erlbaum. Jacoby, L. L., Toth, J. P., & Yonelinas, A. P. (1993). Separating conscious and unconscious influences of memory: Measuring recollection. Journal of Experimental Psychology: Learning, Memory, and Cognition, 122, 139–154. Jacoby, L. L., Yonelinas, A. P., & Jennings, J. M. (1997). The relation between conscious and unconscious (automatic) influences: A declaration of independence. In J. Cohen & J. W. Schooler (Eds.), Scientific approaches to consciousness (pp. 13–47). Mahwah, NJ: Erlbaum. Jennings, J. M., & Jacoby, L. L. (1997). An opposition procedure for detecting age-related deficits in recollection: Telling effects of repetition. Psychology and Aging, 12(2), 352–361. Kalla, T., Downes, J. J., & Van den Broek, M. (2001). The pre-exposure technique: Enhancing the effects of errorless learning in the acquisition of face-name associations. Neuropsychological Rehabilitation, 11(1), 1–16. Kessels, R. P. C., & De Haan, E. H. F. (2003). Implicit learning in memory rehabilitation: A meta-analysis on errorless learning and vanishing cues methods. Journal of Clinical and Experimental Neuropsychology, 25(6), 805–814. Kessels, R. P. C., Te Boekhorst, S., & Postma, A. (2005). The contribution of implicit and explicit memory to the effects of errorless learning: A comparison between young and older adults. Journal of the International Neuropsychological Society, 11, 144–151. Komatsu, S., Mimura, M., Kato, M., Wakamatsu, N., & Kashima, H. (2000). Errorless and effortful processes involved in the learning of face-name associations by patients with alcoholic Korsakoff’s syndrome. Neuropsychological Rehabilitation, 10(2), 113–132.

2813

McKenna, P., & Gerhand, S. (2002). Preserved semantic learning in an amnesic patient. Cortex, 38, 37–58. O’Carroll, R. E., Russell, H. H., Lawrie, S. M., & Johnstone, E. C. (1999). Errorless learning and the cognitive rehabilitation of memory-impaired schizophrenic patients. Psychological Medicine, 29, 105–112. Parkin, A. J., Hunkin, N. M., & Squires, E. J. (1998). Unlearning John Major: The use of errorless learning in the reacquisition of proper names fellowing herpes simplex encephalitis. Cognitive Neuropsychology, 15(4), 361–375. Rodriguez-Fornells, A., Kofidis, C., & M¨unte, T. F. (2004). An electrophysiological study of errorless learning. Cognitive Brain Research, 19, 160–173. Shohamy, D., Myers, C. E., Grossman, S., Sage, J., Gluck, M. A., & Poldrack, R. A. (2004). Cortico-striatal contributions to feedback-based learning: Converging data from neuroimaging and neuropsychology. Brain, 127, 851– 859. Slamecka, N. J., & Graf, P. (1978). The generation effect: Delineation of a phenomenon. Journal of Experimental Psychology: Human Learning and Memory, 4(6), 592–604. Tailby, R., & Haslam, C. (2003). An investigation of errorless learning in memory-impaired patients: Improving the technique and clarifying theory. Neuropsychologia, 41, 1230–1240. Terrace, H. S. (1963). Errorless discrimination learning in the pigeon: Effects of chlorpromazine and imipramine. Science, 140, 318–319. Tulving, E. (1985). Memory and consciousness. Canadian Psychology, 26(1), 1–12. Wilson, B. A., Baddeley, A., Evans, J., & Shiel, A. (1994). Errorless learning in the rehabilitation of memory impaired people. Neuropsychological Rehabilitation, 4(3), 307–326. Yonelinas, A. P. (2002). The nature of recollection and familiarity: A review of 30 years of research. Journal of Memory and Language, 46, 441–517.