Repetition priming of words, pseudowords, and nonwords

In 5 experiments, the authors assessed repetition priming for words, pseudowords, and nonwords using a task that combines an implicit perceptual fluency measure and a recognition memory assessment for each list item. Words and pseudowords generated a consistently strong repetition effect even when there was a failure to recognize the stimulus. In 2 of the experiments, the repetition effect for nonwords was reliably above chance even when there was a failure to recognize the stimulus. The authors propose a parallel distributed processing (PDP) model based on the work of J. McClelland and D. Rumelhart (1985) as a way to understand the mechanisms potentially responsible for the pattern of findings. Although the error-driven nature of learning in the model results in a poor fit to the nonword priming data, this is not endemic to all PDP models. Using a model based on Hebbian learning, the authors instantiate a property that they believe is characteristic of implicit memory--that learning is primarily based on the strengthening of connections between units that become active during the processing of a stimulus. This model provides a far more satisfactory account of the data than does the error-driven model.     

Contribution of perceptual fluency to recognition judgments.

Following a shallow (count vowels) or deep (read) study task, old and new words were tested for both fluency of perception and recognition memory. Subjects first identified a test word as it came gradually into view and then judged it as old or new. Old words were identified faster than new words, indicating implicit, perceptual memory for old words. Independently of this effect, words judged old were identified faster than words judged new, especially after shallow study. Eight experiments examined the possible causal relationship between perceptual fluency and recognition judgements. Experiments 1 to 4 showed that fast identifications per se do not promote old judgments. Accelerating the identification of test items by semantically priming them or making them come more quickly into view did not affect recognition judgments. Experiment 5 showed that the usual association of fast identifications with old judgments is not an artifact of item selection because the association disappeared when the identifications and judgements were segregated into different phases of the test task. Experiments 6 and 7 showed tha the likelihood of old judgments increases directly with the pretested perceptibility of test words, but only after shallow study. Experiment 8 showed that the dependency of recognition judgments on perceptual fluency continues to hold when the requirement to identify the words before judging them is eliminated. We conclude that fluency of perception contributes to recognition judgments, but only when the fluency is produced naturally (e.g., through perceptual memory) and explicit memory is minimal.     

The sensorimotor contributions to implicit memory, familiarity, and recollection

The sensorimotor contributions to memory for prior occurrence were investigated. Previous research has shown that both implicit memory and familiarity draw on gains in stimulus-related processing fluency for old, compared with novel, stimuli, but recollection does not. Recently, it has been demonstrated that processing fluency itself resides in stimulus-specific motor simulations or reenactment (e.g., covert pronouncing simulations for words as stimuli). Combining these lines of evidence, it was predicted that stimulus-specific motor interference preventing simulations should impair both implicit memory and familiarity but leave recollection unaffected. This was tested for words as verbal stimuli associated to pronouncing simulations in the oral muscle system (but also for tunes as vocal stimuli and their associated vocal system, Experiment 2). It was found that oral (e.g., chewing gum), compared with manual (kneading a ball), motor interference prevented mere exposure effects (Experiments 1-2), substantially reduced repetition priming in word fragment completion (Experiment 3), reduced the familiarity estimates in a remember-know task (Experiment 5) and in receiver-operating characteristics (Experiment 6), and completely neutralized familiarity measured by self-reports (Experiment 4) and skin conductance responses (Experiment 7), while leaving recollection and free recall unaffected (across Experiments 1-7). This pattern establishes a rare memory dissociation in healthy participants, that is, explicit without implicit memory or recognizing without feeling familiar. Implications for embodied memory and neuropsychology are discussed.     

Age differences in implicit memory: fragmented object identification and category exemplar generation.

In a cross-sectional study of 164 participants aged 21 to 91, the authors examined age differences on two implicit tests, fragmented object identification (FOI) and category exemplar generation (CEG), and on tests of explicit memory, attention, and verbal fluency. FOI results revealed impaired perceptual skill learning in those over 60 and a decrease in perceptual priming across young, middle-aged, and older groups. CEG priming was impaired in those over 80. Regression analysis revealed explicit contamination of priming on both the FOI and CEG tests. Across the three implicit measures, age accounted for 4 to 13% of the variance when explicit memory was controlled. Semantic fluency predicted CEG priming, suggesting possible frontal lobe involvement on the test. Altogether, results indicate that age has a small but reliable influence on implicit memory.     

Implicit /explicit memory versus analytic/nonanalytic processing: Rethinking the mere exposure effect

In studies of the mere exposure effect, rapid presentation of items can increase liking without accurate recognition. The effect on liking has been explained as a misattribution of fluency caused by prior presentation. However, fluency is also a source of feelings of familiarity. It is, therefore, surprising that prior experience can enhance liking without also causing familiarity-based recognition. We suggest that when study opportunities are minimal and test items are perceptually similar, people adopt an analytic approach, attempting to recognize distinctive features. That strategy fails because rapid presentation prevents effective encoding of such features; it also prevents people from experiencing fluency and a consequent feeling of familiarity. We suggest that the liking-without-recognition effect results from using an effective (nonanalytic) strategy in judging pleasantness, but an ineffective (analytic) strategy in recognition. Explanations of the mere exposure effect based on a distinction between implicit and explicit memory are unnecessary.     

Are two heuristics better than one? The fluency and distinctiveness heuristics in recognition memory

Four experiments were conducted to test the impact of having multiple heuristics (distinctiveness and fluency) available during a recognition test. Recent work by Gallo, Perlmutter, Moore, and Schacter (Memory & Cognition 36:461–466, 2008) suggested that fluency effects are reduced when the distinctiveness heuristic can be applied to a recognition decision. In Experiment 1, we used a response reversal paradigm (Van Zandt & Maldonado-Molina Journal of Experimental Psychology: Learning, Memory, and Cognition 30:1147–1166, 2004) to demonstrate that participants transitioned from an early response strategy that was largely reliant on fluency to a later strategy in which the influences of fluency and distinctiveness were both observable. Experiments 2a, 2b, and 3 showed no evidence for reduction of the fluency heuristic after picture study when the test required a delayed response (Exp. 2a), confidence ratings (Exp. 2b), or the application of conceptual fluency (Exp. 3). The results are consistent with models of memory that assume that familiarity and recollection influence individual memory decisions Wixted (Psychological Review, 114:152–176, 2007).     

流畅性对再认的影响:实验证据及理论解释

流畅性可以影响再认,而且仅影响熟悉性加工的观点已得到大量研究的证实。近年一些研究者采用掩蔽启动范式并结合修改的R/K范式、独立判断的R/K范式等实验范式,操控测验项目的流畅性,发现流畅性影响的可能是猜测或者回想加工,因而质疑这个结论。为解释流畅性对再认的影响,流畅性归因理论侧重对流畅性的归因、冲突-归因理论侧重期待流畅性和实际流畅性之间的冲突、预激活-适应模型侧重启动刺激引起的神经活动激活或适应、线索-学习理论侧重流畅性线索的有效性。未来研究应关注流畅性对来源和联结记忆的影响,并考察流畅性对再认的影响在不同年龄人群或遗忘症人群中的表现是否一致。     

Size and orientation of objects in explicit and implicit memory: A reversal of the dissociation between perceptual similarity and type of test

Memory of size and orientation of objects was tested in explicit and implicit memory tests. Explicit memory was tested by object recognition and by recognition of the congruency of the changed sensory features. Implicit memory was tested by size assessment (Exps. 1 and 2), orientation judgement (Exps. 4 and 5), picture-fragment naming (Exp. 6), and classification (Exps. 3 and 7). Memory of sensory features was investigated by the comparison of performances of test-congruent with test-incongruent stimuli (i.e., same size or orientation vs. different size or orientation). The main result was a dissociation between these two tasks pertaining to the influence of sensory congruency on performance. However, it was in opposition to the usual relationship between the type of test and the perceptual similarity from study to test. In this study explicit, but not implicit, memory depended on sensory congruency. In the explicit tests performances were better when the stimuli were congruent than when they were incongruent. In the implicit test this variation had no influence. To get a repetition effect, it was important only that the object was repeated, and the size of this effect did not depend on sensory congruency. However, a change in another sensory feature — distortions of shape — strongly influenced the size of the repetition effect in the implicit test. Neither transfer-appropriate processing nor a system approach can easily explain this pattern of results. A multi-level, multi-token model is proposed to account for the different effects of sensory features in explicit and implicit memory.     

On the modularity of implicit sequence learning: independent acquisition of spatial, symbolic, and manual sequences

Learning sequential structures is of fundamental importance for a wide variety of human skills. While it has long been debated whether implicit sequence learning is perceptual or response-based, here we propose an alternative framework that cuts across this dichotomy and assumes that sequence learning rests on associative changes that can occur concurrently in distinct processing systems and support the parallel acquisition of multiple uncorrelated sequences. In three experiments we used a serial search task to test critical predictions of this framework. Experiments 1 and 2 showed that participants learnt uncorrelated sequences of auditory letters and manual responses, as well as sequences of visual letters, spatial locations, and manual responses simultaneously, as indicated by a reliable response time (RT) cost incurred by occasional deviants violating either of the sequences. This RT cost was reliable even when participants showing explicit knowledge were excluded. In Experiment 3 learning of spatial and nonspatial sequences was functionally dissociated: whereas a spatio-motor distractor task disrupted learning of location but not of letter sequences, a phonological distractor task had the reverse effect. The distractor tasks thus did not reduce unspecific attentional resources, but selectively disrupted the formation of sequential associations within spatial and nonspatial processing dimensions. These results support the view that implicit sequence learning rests on experience-dependent changes that can occur in parallel in multiple processing systems involved in spatial attention, object recognition, phonological processing, and manual response selection. The resulting dimension-specific sequence representations support independent predictions of what will appear next, where it will appear, and how one will have to respond to it.     

知觉模糊度影响学习的延迟效应

基于迁移适当加工理论,采用连续识别任务范式,通过操纵字词和图片的模糊度来考察知觉模糊非流畅的延迟效应。结果发现：（1）模糊不流畅的材料学习判断值更低;（2） 知觉模糊程度对即时的再认成绩没有影响,但在延迟再认测试中流畅性较低的模糊材料成绩更好。该结果表明实验操纵方式所引发的编码过程和记忆测试所需的检索过程性质上相匹配,而且延迟测试时,知觉非流畅可以促进学习,说明该效应存在边界。     

Effects of repetition priming on recognition memory: testing a perceptual fluency-disfluency model

Five experiments explored the effects of immediate repetition priming on episodic recognition (the "Jacoby-Whitehouse effect") as measured with forced-choice testing. These experiments confirmed key predictions of a model adapted from D. E. Huber and R. C. O'Reilly's (2003) dynamic neural network of perception. In this model, short prime durations pre-activate primed items, enhancing perceptual fluency and familiarity, whereas long prime durations result in habituation, causing perceptual disfluency and less familiarity. Short duration primes produced a recognition preference for primed words (Experiments 1, 2, and 5), whereas long duration primes produced a preference against primed words (Experiments 3, 4, and 5). Experiment 2 found prime duration effects even when participants accurately identified short duration primes. A cued-recall task included in Experiments 3, 4, and 5 found priming effects only for recognition trials that were followed by cued-recall failure. These results suggest that priming can enhance as well as lower familiarity, without affecting recollection. Experiment 4 provided a manipulation check on this procedure through a delay manipulation that preferentially affected recognition followed by cued-recall success.     

Fluency does not express implicit knowledge of artificial grammars

It is commonly held that implicit knowledge expresses itself as fluency. A perceptual clarification task was used to examine the relationship between perceptual processing fluency, subjective familiarity, and grammaticality judgments in a task frequently used to produce implicit knowledge, artificial grammar learning (AGL). Four experiments examined the effects of naturally occurring differences and manipulated differences in perceptual fluency, where decisions were based on a brief exposure to test-strings (during the clarification task only) or normal exposure. When perceptual fluency was not manipulated, it was weakly related to familiarity and grammaticality judgments, but unrelated to grammatical status and hence not a source of accuracy. Counterbalanced grammatical and ungrammatical strings did not differ in perceptual fluency but differed substantially in subjective familiarity. When fluency was manipulated, faster clarifying strings were rated as more familiar and were more often endorsed as grammatical but only where exposure was brief. Results indicate that subjective familiarity derived from a source other than perceptual fluency, is the primary basis for accuracy in AGL. Perceptual fluency is found to be a dumb heuristic influencing responding only in the absence of actual implicit knowledge.     

Perceptual fluency can be used as a cue for categorization decisions

Learning in the prototype distortion task is thought to involve perceptual learning in which category members experience an enhanced visual response (Ashby & Maddox. Annual Review of Psychology, 56, 149-178, 2005). This response likely leads to more-efficient processing, which in turn may result in a feeling of perceptual fluency for category members. We examined the perceptual-fluency hypothesis by manipulating fluency independently from category membership. We predicted that when perceptual fluency was induced using subliminal priming, this fluency would be misattributed to category membership and would affect categorization decisions. In a prototype distortion task, the participants were more likely to judge stimuli that were not members of the category as category members when the nonmembers were made perceptually fluent with a matching subliminal prime. This result suggests that perceptual fluency can be used as a cue during some categorization decisions. In addition, the results provided converging evidence that some types of categorization are based on perceptual learning.     

What makes recognition without awareness appear to be elusive? Strategic factors that influence the accuracy of guesses

Various factors could conceivably promote the accuracy of guesses during a recognition test. Two that we identified in previous studies are forced-choice testing format and high perceptual similarity between the repeat target and novel foil. In restricted circumstances, the relative perceptual fluency of the target can be compared with that of the foil and used as a reliable cue to guide accurate responses that occur without explicit retrieval—a phenomenon we referred to as “implicit recognition.” In this issue, Jeneson and colleagues report a failure to replicate accurate guesses and also a tendency on the part of subjects to hazard guesses infrequently, even though testing circumstances were very similar to those that we used. To resolve this discrepancy, we developed a simple manipulation to encourage either guessing or confident responding. Encouraging guessing increased both the prevalence of guesses and the accuracy of guesses in a recognition test, relative to when confident responding was encouraged. When guessing was encouraged, guesses were highly accurate (as in our previous demonstrations of implicit recognition), whereas when confident responding was encouraged, guesses were at chance levels (as in Jeneson and colleagues'' data). In light of a substantial literature showing high accuracy despite low confidence in certain circumstances, we infer that both the prevalence and accuracy of guessing can be influenced by whether subjects adopt guessing-friendly strategies. Our findings thus help to further characterize conditions likely to promote implicit recognition based on perceptual fluency.In several prior experiments, we reported findings indicative of recognition without awareness (Voss et al. 2008; Voss and Paller 2009). The experiments involved recognition tests for colorful and complex geometric shapes (kaleidoscope images). Subjects attempted to discriminate repeat stimuli (targets) from novel stimuli (foils). In some of our experiments, subjects made recognition responses and also rated the quality of their recognition experience or their confidence in their decision. For example, recognition often occurred with awareness of memory retrieval and with some level of confidence. On the other hand, correct recognition of a target sometimes occurred with no discernable awareness of memory retrieval or confidence; essentially, subjects felt that their response was merely a guess—and yet they were correct.Of course, the reason that a guess might be correct in a recognition test might have nothing at all to do with the subject having retrieved relevant information; the response might be merely a “lucky guess.” Our results, however, provided evidence that processes of implicit memory were operative in producing at least a subset of the correct guesses. In recognition tests using a forced-choice format, targets and foils shared a high degree of perceptual similarity and were displayed side-by-side, and we found that, for guess responses, the repeat stimulus was correctly selected remarkably often. With no stored information (and given that the target occurred equally often on the left side and the right side, and that targets and foils were counterbalanced across subjects), the repeat stimulus should be selected correctly 50% of the time in the long run. In our original report, we found that 82% of the guess responses were correct, which was more accurate than responses when trials with high- or low-confidence responses were pooled together (56%; data combined for all study conditions) (Experiment 2 of Voss et al. 2008). We referred to this phenomenon as recognition without awareness or implicit recognition. For the present discussion, we will use the latter term.Indeed, our results provided several additional reasons for linking implicit memory with this phenomenon of implicit recognition. In one experiment, each trial was classified as either (1) a recognition experience in which subjects recollected episodic information from their initial experience with the target; (2) recognition with familiarity for the target, but no other recall of prior information concerning the target; or (3) a guess with no confidence in the accuracy of the response (Voss and Paller 2009). We found that guesses were approximately as accurate as recollection responses (73% vs. 79%, respectively, averaged across encoding conditions), and that guesses were more accurate than decisions based on familiarity (59%, averaged across encoding conditions).Another feature of these experiments was that we contrasted two types of learning conditions. In one condition, to-be-remembered stimuli were viewed while subjects simultaneously performed a verbal working memory task. This task required that the subject listen to a spoken digit on each trial and respond according to whether the digit on the prior trial was odd or even (i.e., a one-back task). In the other condition, there were no spoken digits, and attention could be allocated fully to viewing the to-be-remembered stimuli. In several different experiments, recognition accuracy was higher with divided-attention study than with full-attention study. Although this is a highly unusual outcome for recognition performance, it was clear that divided attention during the study led to relatively less confidence during the recognition test, such that guessing was more prevalent, and these guess responses were highly accurate.Notably, these two key results—highly accurate guessing, and a recognition advantage for divided over full attention at study—were not obtained when recognition was tested with a yes–no format (targets and highly similar foils randomly intermixed and shown one stimulus at a time), or when a forced-choice test was prepared such that each target was paired with a random foil rather than a highly similar foil (Voss et al. 2008). On the basis of these findings, as well as additional results from electrophysiological recordings (described below in the Discussion section), we argued that subjects were able to weigh the relative perceptual fluency of the target and the foil only for forced-choice tests with high target/foil similarity, and then they could use this fluency cue to guide accurate selection of the target (Voss and Paller 2009).We aim to develop a line of reasoning to clarify why implicit recognition might tend to operate preferentially in certain circumstances, such as when the relative perceptual fluency of targets versus foils is likely to serve as a useful cue, and when the ability to remember specific stimulus details does not provide a useful cue (as is the case when these details are largely shared between the target and the foil). In many situations, however, perceptual fluency may not be a good basis for making recognition judgments. Often, accurate recognition reflects conceptual elaboration about the meaning of an event, and the conceptual features are typically remembered more robustly than the set of stimulus features perceived during the course of the event. Thus, implicit recognition may be less likely to guide a response in a recognition test in the presence of confident memory for the target. Dividing attention during encoding resulted in lower confidence during the recognition test, and this may have been one factor that promoted reliance on signals of relative perceptual fluency. Of course, there may be other factors that also promote or inhibit this type of strategy in a recognition test.     

Distinguishing familiarity from fluency for the compound word pair effect in associative recognition

We examined whether processing fluency contributes to associative recognition of unitized pre-experimental associations. In Experiments 1A and 1B, we minimized perceptual fluency by presenting each word of pairs on separate screens at both study and test, yet the compound word (CW) effect (i.e., hit and false-alarm rates greater for CW pairs with no difference in discrimination) did not reduce. In Experiments 2A and 2B, conceptual fluency was examined by comparing transparent (e.g., hand bag) and opaque (e.g., rag time) CW pairs in lexical decision and associative recognition tasks. Lexical decision was faster for transparent CWs (Experiment 2A) but in associative recognition, the CW effect did not differ by CW pair type (Experiment 2B). In Experiments 3A and 3B, we examined whether priming that increases processing fluency would influence the CW effect. In Experiment 3A, CW and non-compound word pairs were preceded with matched and mismatched primes at test in an associative recognition task. In Experiment 3B, only transparent and opaque CW pairs were presented. Results showed that presenting matched versus mismatched primes at test did not influence the CW effect. The CW effect in yes-no associative recognition is due to reliance on enhanced familiarity of unitized CW pairs.     

加工流畅性对学习判断字体大小效应的影响

以自定步调学习时间和习得试验次数为加工流畅性指标,通过操纵不同字号的词对考察了加工流畅性对学习判断字体大小效应的影响。结果发现：（1）字体大小影响学习判断,但不影响回忆成绩;（2）不同字体大小的词对在加工流畅性（学习时间和学习次数）上存在差异,仅自定步调学习时间测量的加工流畅性对学习判断字体大小效应有贡献。这些结果说明学习判断的字体大小效应是一种元认知错觉现象,部分支持了加工流畅性假说。     

The revelation effect for item and associative recognition: Familiarity versus recollection

The revelation effect occurs when items on a recognition test are more likely to be judged as being old if they are preceded by a cognitive task that involves the processing of similar types of stimuli. This effect was examined for item (single-word) and associative (word-pair) recognition. We found, in Experiments 1 and 2, a revelation effect for item, but not for associative recognition under normal study conditions. A revelation effect for both item and associative recognition was observed in Experiments 3 and 4 when study time was extremely brief, thus limiting the encoding of information that would support recall or recollection. In Experiment 5, we demonstrated that the revelation effect for item recognition is eliminated when item recognition decisions are made in the context of a study item. The results show that the revelation task influenced recognition decisions based on familiarity, but not decisions that involved recall or recollection.     

Implicit memory for auditorily presented threatening stimuli: a process-dissociation approach

The investigation of unconscious cognition involves especially problems with the methodology of measuring implicit and explicit proportions of different task performances. In this study the process dissociation procedure of Jacoby and its modification within the multinomial modelling framework for an indirect word-nonword-discrimination task is applied to a sample of 45 healthy students. The paradigm includes acoustically presented stimuli. During a learning phase, subjects listened to a series of neutral and threatening words. Performance was tested by letting subjects decide whether a presented stimulus (masked with white noise at signal-noise ratio of -17 dB or unmasked) had been a word or a nonword. Within this paradigm, implicit cognition occurs when (a) a word is more probably correctly recognized as "word" after presentation during the learning phase (typical priming effect) or when (b) a nonword derived from a word is more probably falsely recognized as "word" after its corresponding word had been presented during the learning phase (effect of implicit cognition given perceptual fluency). Frequencies for hits and false alarms were analyzed within the multinomial model which allows estimating parameters for the correct discrimination of words (c), the response bias (b), the classical priming effect (u1), and the parameter for the priming effect of "old" nonwords (u2). Under masked stimuli the multinomial model showed implicit cognition, an effect not equally found for neutral and threatening words. Threatening words exhibited a significantly higher portion of implicit cognition than neutral ones. Given the statistical complexity of multinomial models, the application of this method was explained in detail.     

The sensory match effect in recognition memory: Perceptual fluency or episodic trace?

The sensory match effect in recognition memory refers to the finding that recognition is better when the sensory form in which an item is tested is the same as that in which it was studied. This paper examines the basis for the sensory match effect by manipulating whether a studied fragmented picture is tested with the same or a complementary set of fragments in a recognition memory test (Experiment 1) and in a fragment-identification test (Experiment 2). Assuming that fragment identification is a direct measure of perceptual fluency, we expected identical patterns of results across the two tests if perceptual fluency accounted for the sensory match effect in recognition memory. Instead, recognition memory showed a robust overall sensory match effect (the same fragmented image was recognized better than the complementary image), whereas fragment identification showed no overall sensory match effect (the same fragmented image was identified no better than the complementary fragmented image). Experiments 3 and 4 combined the two responses and showed that the basis for the sensory match effect in recognition memory was a subject’s ability to recognize the matching fragments in the absence of conceptual information (when the test stimulus could not be identified), supporting the idea that the episodic trace of the sensory code is responsible for the sensory match effect in recognition memory. Experiment 5 demonstrated that subjects are able to use this sensory code as the sole basis for recognition memory.     

Change in perceptual form attenuates the use of the fluency heuristic in recognition

Four experiments (total N=295) were conducted to determine whether within-modality changes in perceptual form between the study and the test phases of an experiment would moderate the role of the fluency heuristic in recognition memory. Experiment 1 showed that a change from pictures to words reduced the role of fluency in recognition memory. In Experiment 2, the same result was found using counterfeit study lists that supposedly consisted of pictures or words. Experiments 3 and 4 showed that changes in the font used to present the study and test words also attenuated the contribution of fluency to the recognition decision when font change was manipulated between subjects, but not within subjects. Results suggest that the fluency heuristic is subject to metacognitive control, since participants' attributions of perceptual fluency depend on the perceived usefulness of fluency as a cue to recognition.