Attention and implicit memory tests: the effects of varying attentional load on conceptual priming

Protective effects of physical activity on episodic memory during aging are explained by executive functioning

Aging is marked by a memory decline related to an executive function decline. Physical activity (PA) has beneficial effects on both executive functions and memory, especially in aging. The protective effects of PA on these two cognitive abilities have always been studied separately, despite the well-established relationship between memory and executive functions. Our objective was to explore whether the benefits of PA on memory could be explained by reduced age-related changes in executive functions.Nineteen young adults (27.16 years old) and 25 older adults (69.64 years old) performed a resource-dependent memory task, three executive tasks and completed a PA questionnaire (measuring sports and leisure PA). Age group and PA effects on memory and executive performance were analyzed with generalized linear models. Mediation analyses were calculated using method of causal steps approach with a non-parametric bootstrapping procedure.The results confirmed the effects of age and PA on memory and executive performance. A significant interaction confirmed the protective effect of PA on age-related cognitive performance. PA was positively correlated with performance in both memory and executive tasks, but only in the older adults. Although each predictor alone (age, executive functions and PA) significantly explained memory performance in older adults, only the effect of PA on memory performance remained significant when all the predictors were introduced in the analyses.PA mediates the effects of age and executive functions on memory performance. This suggests that PA protects older adults against memory decline by reducing the decline in executive functioning.

Behavioral Signatures of Memory Resources for Language: Looking beyond the Lexicon/Grammar Divide

Although there is a broad consensus that both the procedural and declarative memory systems play a crucial role in language learning, use, and knowledge, the mapping between linguistic types and memory structures remains underspecified: by default, a dual-route mapping of language systems to memory systems is assumed, with declarative memory handling idiosyncratic lexical knowledge and procedural memory handling rule-governed knowledge of grammar. We experimentally contrast the processing of morphology (case and aspect), syntax (subordination), and lexical semantics (collocations) in a healthy L1 population of Polish, a language rich in form distinctions. We study the processing of these four types under two conditions: a single task condition in which the grammaticality of stimuli was judged and a concurrent task condition in which grammaticality judgments were combined with a digit span task. Dividing attention impedes access to declarative memory while leaving procedural memory unaffected and hence constitutes a test that dissociates which types of linguistic information each long-term memory construct subserves. Our findings confirm the existence of a distinction between lexicon and grammar as a generative, dual-route model would predict, but the distinction is graded, as usage-based models assume: the hypothesized grammar-lexicon opposition appears as a continuum on which grammatical phenomena can be placed as being more or less "ruly" or "idiosyncratic." However, usage-based models, too, need adjusting as not all types of linguistic knowledge are proceduralized to the same extent. This move away from a simple dichotomy fundamentally changes how we think about memory for language, and hence how we design and interpret behavioral and neuroimaging studies that probe into the nature of language cognition.

The Presence of a Visual Dividing Line Increases Consumer Memory Through Attention Grabbing

Marketers often use a visual line to divide the product information on an advertisement into left-right (or top-bottom) segments for aesthetic or categorization purposes. The present research examined the effect of the dividing line on the consumer memory. Across three studies (including an eye-tracking study and a field one), we showed that the presence of a dividing line enhances consumers’ memory about the products displayed on the left/top of an advertisement. This effect occurs because the dividing line orients participants’ first eye fixation to the left/top area of the advertisement, such that their visual attention is largely restricted to that area and they could better remember the contents displayed on that area. The theoretical contributions and implications for marketers and consumers are discussed.

Reward Salience and Choice in a Controlling Context: A Lab Experiment

One of the challenges in the motivation literature is examining the simultaneous effect of different motivational mechanisms on overall motivation and performance. The motivational congruence theory addresses this by stipulating that different motivational mechanisms can reinforce each other if they have similar effects on the perceived locus of causality. Reward salience and choice are two motivational mechanisms which their joint effects have been long debated. Built upon the motivational congruence effect, a recent empirical study affirms that a salient reward in a condition characterized by lack of choice and a non-salient reward in a condition characterized by provision of choice both increase overall motivation and performance. In this study, we examine the effect of reward salience and choice on overall motivation and performance in a controlling context, an effect which has not been studied before. A 2 (choice: present, absent) × 3 (reward: salient, non-salient, none) factorial design was conducted to examine research hypotheses. The results show that under controlling conditions, salient reward improves overall motivation and performance compared to non-salient and no-reward conditions.

Clear-Cut Terms and Culture-Sensitive Characteristics of Distinctive Casual Sexual Relationships in Portuguese Emerging Adults

Casual sexual relationships (CSR) are increasingly common but limited empirical research has addressed their terminology and distinctive characteristics. This study sought to identify the most clear-cut terms and to consider how culture-sensitive characteristics distinguish casual sexual relationships among Portuguese emerging adults (N = 262, 18-29 years old). We combined two qualitative studies - one by association and another by free recall - to ascertain the clarity of the terms, plus a quantitative study to further characterize and differentiate them. Participants were asked to match descriptions of CSRs with the respective terms by which they are known (Study 1). The same was investigated using an evocation task requesting that participants produce the terms by which the described CSRs are known (Study 2). Binary logistic regressions were performed to analyze the associations between encounters and labels chosen, taking the effect of gender and age into account. In the third study, participants rated the degree to which eight characteristics were present in the types of CSR, a simultaneous task that led to greater understanding of their descriptive and differentiating characteristics. Multivariate analysis of variance was used, with gender and age as covariates. We conclude that two types of CSR - friends with benefits and one-night stand - and, to a lesser extent, making out, are understood and associated with consensual labels, also found by free-recall. These CSRs proved to be distinct, as they are understood as more different than similar in a set of psychoemotional, behavioral, and sexual characteristics.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s12119-021-09859-0.

Folk standards of sound judgment: Rationality Versus Reasonableness

Normative theories of judgment either focus on rationality (decontextualized preference maximization) or reasonableness (pragmatic balance of preferences and socially conscious norms). Despite centuries of work on these concepts, a critical question appears overlooked: How do people's intuitions and behavior align with the concepts of rationality from game theory and reasonableness from legal scholarship? We show that laypeople view rationality as abstract and preference maximizing, simultaneously viewing reasonableness as sensitive to social context, as evidenced in spontaneous descriptions, social perceptions, and linguistic analyses of cultural products (news, soap operas, legal opinions, and Google books). Further, experiments among North Americans and Pakistani bankers, street merchants, and samples engaging in exchange (versus market) economy show that rationality and reasonableness lead people to different conclusions about what constitutes good judgment in Dictator Games, Commons Dilemma, and Prisoner's Dilemma: Lay rationality is reductionist and instrumental, whereas reasonableness integrates preferences with particulars and moral concerns.

Divided attention reduces resistance to distraction at encoding but not retrieval

Older adults show implicit memory for previously seen distraction, an effect attributed to poor attentional control. It is unclear whether this effect results from lack of control over encoding during the distraction task, lack of retrieval constraint during the test task, or both. In the present study, we simulated poor distraction control in young adults using divided attention at encoding, at retrieval, at both times, or not at all. The encoding task was a 1-back task on pictures with distracting superimposed letter strings, some of which were words. The retrieval task was a word fragment completion task testing implicit memory for the distracting words. Attention was divided using an auditory odd digit detection task. Dividing attention at encoding, but not at retrieval, resulted in significant priming for distraction, which suggests that control over encoding processes is a primary determinant of distraction transfer in populations with low inhibitory control (e.g. older adults).

Not explicit but implicit memory is influenced by individual perception style

Not only explicit but also implicit memory has considerable influence on our daily life. However, it is still unclear whether explicit and implicit memories are sensitive to individual differences. Here, we investigated how individual perception style (global or local) correlates with implicit and explicit memory. As a result, we found that not explicit but implicit memory was affected by the perception style: local perception style people more greatly used implicit memory than global perception style people. These results help us to make the new effective application adapting to individual perception style and understand some clinical symptoms such as autistic spectrum disorder. Furthermore, this finding might give us new insight of memory involving consciousness and unconsciousness as well as relationship between implicit/explicit memory and individual perception style.

Not all identification tasks are born equal: testing the involvement of production processes in perceptual identification and lexical decision

The distinction between identification and production processes suggests that implicit memory should require more attention resources when there is a competition between alternative solutions during the test phase. The present two experiments assessed this hypothesis by examining the effects of divided attention (DA) at encoding on the high- and low-response-competition versions of perceptual identification (Experiment 1) and lexical decision (Experiment 2). In both experiments, words presented in the high-response-competition condition had many orthographic neighbours and at least one higher-frequency neighbour, whereas words presented in the low-response-competition condition had few orthographic neighbours and no higher-frequency neighbour. Consistent with the predictions of the identification/production distinction, Experiment 1 showed that DA reduced repetition priming in the high-, but not in the low-response-competition version of perceptual identification; in contrast, DA had comparable effects in the two versions of lexical decision (Experiments 2). These findings provide the first experimental evidence in support of the hypothesis that perceptual identification, a task nominally based on identification processes, might involve a substantive production component.

Semantic Retrieval, Mnemonic Control, and Prefrontal Cortex

Accessing stored knowledge is a fundamental function of the cognitive and neural architectures of memory. Here, the authors review evidence from cognitive-behavioral paradigms, neuropsychological studies ofpatients with focal neural insult, and functional brain imaging concerning the mechanisms underlying retrieval ofsemantic knowledge and their association with prefrontal cortex. First, the authors examine behavioral and neuropsychological evidence distinguishing between controlled and automatic semantic retrieval. Then the authors review the subregions of prefrontal cortex that functional neuroimaging has associated with semantic retrieval across a range ofmemory demanding tasks. Finally, two hypotheses concerning the nature ofprocessing in these brain regions–the controlled semantic retrieval and selection hypotheses–are critically examined, and a possible synthesis is proposed.

Binocular Rivalry Disrupts Visual Priming

Many results implicate perceptual processing in repetition priming, but little is known of potential mechanisms for priming. A new method was used to help determine the processing stage at which priming occurs. Priming pictures were presented under dominance or suppression generated by binocular rivalry. Although low-level, sensory attributes can be processed under rivalry suppression, there is no evidence that repetition priming can be supported by such low-level processing. Priming was found only for stimuli that were processed sufficiently to be identified in the priming stage. The results demonstrate that repetition priming requires processing of stimulus attributes into relatively high-level representations.

The role of attention in emotional memory enhancement in pathological and healthy aging

After short delays between encoding and retrieval, healthy young participants have better memory performance for emotional stimuli than for neutral stimuli. Divided-attention paradigms suggest that this emotional enhancement of memory (EEM) is due to different attention mechanisms involved during encoding: automatic processing for negative stimuli, and controlled processing for positive stimuli. As far as we know, no study on the influence of these factors on EEM in Alzheimer's disease (AD) and mild cognitive impairment (MCI) patients, as compared to healthy young and older controls, has been conducted. Thus, the goal of our study was to ascertain whether the EEM in these populations depends on the attention resources available at encoding. Participants completed two encoding phases: full attention (FA) and divided attention (DA), followed by two retrieval phases (recognition tasks). There was no EEM on the discrimination accuracy, independently of group and encoding condition. Nevertheless, all participants used a more liberal response criterion for the negative and positive stimuli than for neutral ones. In AD patients, larger numbers of false recognitions for negative and positive stimuli than for neutral ones were observed after both encoding conditions. In MCI patients and in healthy older and younger controls this effect was observed only for negative stimuli, and it depended on the encoding condition. Thus, this effect was observed in young controls after both encoding conditions, in older controls after the DA encoding, and in MCI patients after the FA encoding. In conclusion, our results suggest that emotional valence does not always enhance discrimination accuracy. Nevertheless, in certain conditions related to the attention resources available at encoding, emotional valence, especially the negative one, enhances the subjective feeling of familiarity and, consequently, engenders changes in response bias. This effect seems to be sensitive to the age and the pathology of participants.

Does long-term object priming depend on the explicit detection of object identity at encoding?

It is currently unclear whether objects have to be explicitly identified at encoding for reliable behavioral long-term object priming to occur. We conducted two experiments that investigated long-term object and non-object priming using a selective-attention encoding manipulation that reduces explicit object identification. In Experiment 1, participants either counted dots flashed within an object picture (shallow encoding) or engaged in an animacy task (deep encoding) at study, whereas, at test, they performed an object-decision task. Priming, as measured by reaction times (RTs), was observed for both types of encoding, and was of equivalent magnitude. In Experiment 2, non-object priming (faster RTs for studied relative to unstudied non-objects) was also obtained under the same selective-attention encoding manipulation as in Experiment 1, and the magnitude of the priming effect was equivalent between experiments. In contrast, we observed a linear decrement in recognition memory accuracy across conditions (deep encoding of Experiment 1 > shallow encoding Experiment 1 > shallow encoding of Experiment 2), suggesting that priming was not contaminated by explicit memory strategies. We argue that our results are more consistent with the identification/production framework than the perceptual/conceptual distinction, and we conclude that priming of pictures largely ignored at encoding can be subserved by the automatic retrieval of two types of instances: one at the motor level and another at an object-decision level.

Attention and repetition priming in the verb generation task

Transfer-appropriate processing (TAP) and identification-production frameworks predict that repetition priming will be reduced by encoding-phase divided attention (DA) in implicit memory tasks that involve conceptual analysis of test stimuli and require responses that go beyond the identification of the test cue. This prediction was tested using the verb generation task. Verb generation priming was weakly affected by a number classification distracting task at encoding that impacted recognition, was affected more by a more demanding mental arithmetic task, and was abolished entirely by a selective attention manipulation. Priming originating largely from a process unique to the verb generation task was also found to be attention-sensitive. DA affected priming equivalently for high-competition and low-competition items, against the identification-production framework which predicts greater DA effects on priming in high-competition conditions. The results fit comfortably within the TAP framework.

Understanding gender bias in face recognition: effects of divided attention at encoding

Prior research has demonstrated a female own-gender bias in face recognition, with females better at recognizing female faces than male faces. We explored the basis for this effect by examining the effect of divided attention during encoding on females' and males' recognition of female and male faces. For female participants, divided attention impaired recognition performance for female faces to a greater extent than male faces in a face recognition paradigm (Study 1; N=113) and an eyewitness identification paradigm (Study 2; N=502). Analysis of remember-know judgments (Study 2) indicated that divided attention at encoding selectively reduced female participants' recollection of female faces at test. For male participants, divided attention selectively reduced recognition performance (and recollection) for male stimuli in Study 2, but had similar effects on recognition of male and female faces in Study 1. Overall, the results suggest that attention at encoding contributes to the female own-gender bias by facilitating the later recollection of female faces.

Contextual representations increase analogue traumatic intrusions: evidence against a dual-representation account of peri-traumatic processing

BACKGROUND AND OBJECTIVES

Information processing accounts of post-traumatic stress disorder (PTSD) state that intrusive memories emerge due to a lack of integration between perceptual and contextual trauma representations in autobiographical memory. This hypothesis was tested experimentally using an analogue trauma paradigm in which participants viewed an aversive film designed to elicit involuntary recollections.

METHOD

Participants viewed scenes from the film either paired with contextual information or with the contextual information omitted. After viewing the film participants were asked to record for one week any involuntary intrusions for the film using a provided intrusions diary.

RESULTS

The results revealed a significant increase in analogue intrusions for the film when viewed with contextual information in comparison to when the film was viewed with the contextual information omitted. In contrast there was no effect of contextual information on valence ratings or voluntary memory for the film, or on the reported vividness and emotionality of the intrusions.

LIMITATIONS

The analogue trauma paradigm may have failed to reproduce the effect of extreme stress on encoding that is postulated to occur during PTSD.

CONCLUSIONS

The findings have potential implications for trauma intervention as they suggest that the contextual understanding of a scene during encoding can be integral to the subsequent occurrence of traumatic intrusions. The pattern of results found in the study are inconsistent with dual-representation accounts of intrusive memory formation, and instead provide new evidence that contextual representations play a casual role in increasing the frequency of involuntary intrusions for traumatic material.

Intact implicit verbal relational memory in medial temporal lobe amnesia

To elucidate the role of the hippocampus in unaware relational memory, the present study examined the performance of amnesic patients with medial temporal lobe (MTL) lesions on a cued category-exemplar generation task. In contrast to a prior study in which amnesic patients showed impaired performance (Verfaellie et al., Cognitive, Affective, and Behavioral Neuroscience, 2006, 6, 91-101), the current study employed a task that required active processing of the context word at test. In this version of the task, amnesic patients, like control participants, showed enhanced category exemplar priming when the context word associated with the target at study was reinstated at test. The finding of intact implicit memory for novel associations following hippocampal lesions in a task that requires flexible use of retrieval cues is inconsistent with a relational memory view that suggests that the hippocampus is critical for all forms of relational memory, regardless of awareness. Instead, it suggests that unaware memory for within-domain associations does not require MTL mediation.

Encoding Tasks Dissociate the Effects of Divided Attention on Category-Cued Recall and Category-Exemplar Generation

The combined effects of encoding tasks and divided attention upon category-exemplar generation and category-cued recall were examined. Participants were presented with pairs of words each comprising a category name and potential example of that category. They were then asked to indicate either (i) their liking for both of the words or (ii) if the exemplar was a member of the category. It was found that divided attention reduced performance on the category-cued recall task under both encoding conditions. However, performance on the category-exemplar generation task remained invariant across the attention manipulation following the category judgment task. This provides further evidence that the processes underlying performance on conceptual explicit and implicit memory tasks can be dissociated, and that the intentional formation of category-exemplar associations attenuates the effects of divided attention on category-exemplar generation.

The relationship between divided attention and implicit memory: a meta-analysis

This article reports a meta-analysis comparing the size of repetition priming in full and divided-attention (DA) conditions. The main analysis included 38 effect sizes (ES) extracted from 21 empirical studies, for a total of 2074 (full-attention) and 2148 (divided-attention) participants. The mean weighted ES was 0.357 (95% CI=0.278-0.435), indicating that divided attention produced a small, but significant, negative effect on implicit memory. Overall, the distinction between identification and production priming provided the best fit to empirical data (with the effect of DA being greater for production tests), whereas there was no significant difference between perceptual and conceptual priming. A series of focused contrasts suggested that word-stem completion might be influenced by lexical-conceptual processes, and that perceptual identification might involve a productive component. Implications for current theories of implicit memory are discussed.

Beyond perception: testing for implicit conceptual traces in high-load tasks

The present commentary addresses the main results obtained in the Butler and Klein [Butler, B. C., & Klein, R. (2009). Inattentional blindness for ignored words: Comparison of explicit and implicit memory tasks. Consciousness and Cognition, 18, 811-819.] study and discusses them in relation to the Perceptual Load Theory of Lavie [Lavie, N. (1995). Perceptual load as a necessary condition for selective attention. Journal of Experimental Psychology: Human Perception and Performance, 21, 451-68.]. The authors claim that the use of implicit indexes of conceptual distractor processing in high-load situations would be an important addition to the load literature, which would benefit the research field regardless of their positive or negative findings.

Effects of dividing attention during encoding on perceptual priming of unfamiliar visual objects

According to the distractor-selection hypothesis (Mulligan, 2003), dividing attention during encoding reduces perceptual priming when responses to non-critical (i.e., distractor) stimuli are selected frequently and simultaneously with critical stimulus encoding. Because direct support for this hypothesis comes exclusively from studies using familiar word stimuli, the present study tested whether the predictions of the distractor-selection hypothesis extend to perceptual priming of unfamiliar visual objects using the possible/impossible object decision test. Consistent with the distractor-selection hypothesis, Experiments 1 and 2 found no reduction in priming when the non-critical stimuli were presented infrequently and non-synchronously with the critical target stimuli, even though explicit recognition memory was reduced. In Experiment 3, non-critical stimuli were presented frequently and simultaneously during encoding of critical stimuli; however, no decrement in priming was detected, even when encoding time was reduced. These results suggest that priming in the possible/impossible object decision test is relatively immune to reductions in central attention and that not all aspects of the distractor-selection hypothesis generalise to priming of unfamiliar visual objects. Implications for theoretical models of object decision priming are discussed.

Implications of basic science research for brain injury rehabilitation: a focus on intact learning mechanisms

Within a theoretical framework for rehabilitation that distinguishes between automatic and controlled processes, this article reviews basic science research and addresses the following issues: What cognitive abilities remain relatively intact after severe traumatic brain injury, and how can we incorporate intact skills into rehabilitative techniques? The reviewed research indicates that individuals with severe traumatic brain injury (a) generally perform similar to controls on cognitive tasks (or task components) that require automatic and implicit processes as opposed to consciously controlled processes; (b) can learn through implicit learning mechanisms; and (c) can acquire and use automatic processes in complex, cognitive task performance.

Endogenous versus exogenous attentional cuing effects on memory

Three experiments were conducted to investigate the influence of early attentional cuing effects on subsequent memory. In an incidental study phase, a cue preceded two simultaneously displayed words. An endogenous cue (row of arrows pointing toward one word) or an exogenous cue (row of stars at the location of one word) indicated which word to read aloud. In a subsequent test phase, memory for these cued and uncued words was measured. In Experiment 1, these attentional manipulations had almost no effect on subsequent implicit memory measured using a speeded reading (naming) test. Experiments 2 and 3 demonstrated that, on an explicit memory test, words were reliably better recognized in the endogenous condition than in the exogenous condition. These results suggest that endogenous attentional cues promote more active processing and hence elaboration of words, assisting their subsequent conscious retrieval.

Implicit memory development in school-aged children with attention deficit hyperactivity disorder (ADHD): conceptual priming deficit?

Previous research has shown that children with attention deficit hyperactivity disorder (ADHD) often demonstrate performance deficits on effortful, strategic memory tasks, whereas relatively rote tasks of memory reveal no such deficit. Thus far, research in this domain has focused primarily on explicit memory. This study examined performance on multiple measures of implicit and explicit memory in children aged 7 to 14 years with and without ADHD. Memory for words and pictures was assessed at 15-min and 24-hr intervals. ADHD and non-ADHD groups performed similarly on tests of explicit memory (category-cued recall and recognition) and on perceptual aspects of implicit memory (word stem completion and picture fragment identification) as a function of age, retention interval, and stimulus format (i.e., picture or word). However, there was no evidence of priming on a conceptual implicit memory test (category exemplar generation) for boys with ADHD. This type of conceptual task, which is likely mediated by frontal systems, may indicate a unique memory deficit associated with ADHD.

What does it take to implicitly prime low-frequency category exemplars?

Prominent views of implicit priming agree that repetition of category exemplars should increase the probability of the exemplar coming to mind on a category production test. This prediction has been borne out in the data of numerous experiments that have used relatively high-frequency exemplars, but experiments that have used lower frequency exemplars have reported reduced or no priming on category production tests. Frameworks of memory disagree on why frequency would affect priming. The authors report 3 experiments, the first of which shows no priming of low-frequency exemplars under circumstances that yield priming of higher frequency instances. The second 2 experiments show that low-frequency instances can be primed, but the prior experience must bias the comprehension of the category label, not the exemplar.

Selective attention modulates neural substrates of repetition priming and "implicit" visual memory: suppressions and enhancements revealed by FMRI

Attention can enhance processing for relevant information and suppress this for ignored stimuli. However, some residual processing may still arise without attention. Here we presented overlapping outline objects at study, with subjects attending to those in one color but not the other. Attended objects were subsequently recognized on a surprise memory test, whereas there was complete amnesia for ignored items on such direct explicit testing; yet reliable behavioral priming effects were found on indirect testing. Event-related fMRI examined neural responses to previously attended or ignored objects, now shown alone in the same or mirror-reversed orientation as before, intermixed with new items. Repetition-related decreases in fMRI responses for objects previously attended and repeated in the same orientation were found in the right posterior fusiform, lateral occipital, and left inferior frontal cortex. More anterior fusiform regions also showed some repetition decreases for ignored objects, irrespective of orientation. View-specific repetition decreases were found in the striate cortex, particularly for previously attended items. In addition, previously ignored objects produced some fMRI response increases in the bilateral lingual gyri, relative to new objects. Selective attention at exposure can thus produce several distinct long-term effects on processing of stimuli repeated later, with neural response suppression stronger for previously attended objects, and some response enhancement for previously ignored objects, with these effects arising in different brain areas. Although repetition decreases may relate to positive priming phenomena, the repetition increases for ignored objects shown here for the first time might relate to processes that can produce "negative priming" in some behavioral studies. These results reveal quantitative and qualitative differences between neural substrates of long-term repetition effects for attended versus unattended objects.

Perceptual implicit memory relies on intentional, load-sensitive processing at encoding

In two experiments, we examined whether the encoding processes leading to perceptual implicit memory satisfied the intentionality and load insensitivity criteria for automaticity. Whether participants intended to process words or digits, in displays containing both, was manipulated in Experiment 1. Results showed an effect of intention on a subsequent perceptual identification task and a recognition task. Load (one, two, and four words) and exposure duration (1,000, 600, and 200 msec) at encoding were manipulated in Experiment 2. Recognition was affected by both variables, but performance on the perceptual identification task was affected only by load. In both experiments, the results showed that controlled (intentional, load-sensitive) processing of words at encoding is essential for later perceptual implicit memory. That is, the encoding processes leading to perceptual implicit memory fail both criteria of automaticity.

Effects of divided attention and speeded responding on implicit and explicit retrieval of artificial grammar knowledge

The artificial grammar (AG) learning literature (see, e.g., Mathews et al., 1989; Reber, 1967) has relied heavily on a single measure of implicitly acquired knowledge. Recent work comparing this measure (string classification) with a more indirect measure in which participants make liking ratings of novel stimuli (e.g., Manza & Bornstein, 1995; Newell & Bright, 2001) has shown that string classification (which we argue can be thought of as an explicit, rather than an implicit, measure of memory) gives rise to more explicit knowledge of the grammatical structure in learning strings and is more resilient to changes in surface features and processing between encoding and retrieval. We report data from two experiments that extend these findings. In Experiment 1, we showed that a divided attention manipulation (at retrieval) interfered with explicit retrieval of AG knowledge but did not interfere with implicit retrieval. In Experiment 2, we showed that forcing participants to respond within a very tight deadline resulted in the same asymmetric interference pattern between the tasks. In both experiments, we also showed that the type of information being retrieved influenced whether interference was observed. The results are discussed in terms of the relatively automatic nature of implicit retrieval and also with respect to the differences between analytic and nonanalytic processing (Whittlesea & Price, 2001).

Conceptual processing effects on automatic memory

In the present study, influences of conceptual processing on automatic forms of memory were investigated, using a category production task. The experiment employed Jacoby's (1991) process dissociation procedure and fits of multinomial models to estimate conscious and automatic memory for semantic and graphemic study tasks. Memory estimates from a generate-source model indicated more automatic memory for semantic than for graphemic items on the category production task. These results provide support for conceptual processing influences on automatic forms of memory.

Effects of cross-modal and intramodal division of attention on perceptual implicit memory

Extant results motivate 3 hypotheses on the role of attention in perceptual implicit memory. The first proposes that only intramodal manipulations of attention reduce perceptual priming. The second attributes reduced priming to the effects of distractor selection operating in a central bottleneck process. The third proposes that manipulations of attention only affect priming via disrupted stimulus identification. In Experiment 1, a standard cross-modal manipulation did not disrupt priming in perceptual identification. However, when study words and distractors were presented synchronously, cross-modal and intramodal distraction reduced priming. Increasing response frequency in the distractor task produced effects of attention regardless of target-distractor synchrony. These effects generalized to a different category of distractors arguing against domain-specific interference. The results support the distractor-selection hypothesis.

The origins of levels-of-processing effects in a conceptual test: evidence for automatic influences of memory from the process-dissociation procedure

In three experiments, we explored automatic influences of memory in a conceptual memory task, as affected by a levels-of-processing (LoP) manipulation. We also explored the origins of the LoP effect by examining whether the effect emerged only when participants in the shallow condition truncated the perceptual processing (the lexical-processing hypothesis) or even when the entire word was encoded in this condition (the conceptual-processing hypothesis). Using the process-dissociation procedure and an implicit association-generation task, we found that the deep encoding condition yielded higher estimates of automatic influences than the shallow condition. In support of the conceptual processing hypothesis, the LoP effect was found even when the shallow task did not lead to truncated processing of the lexical units. We suggest that encoding for meaning is a prerequisite for automatic processing on conceptual tests of memory.

Conceptual and perceptual processes in prospective remembering: differential influence of attentional resources

Does prospective remembering rely on strategic, attentionally demanding processes? We report three experiments suggesting that the extent to which attentional processes are required varies according to the character of ongoing task processing. Study-test changes in the semantic context of targets had a negative effect on prospective memory performance when participants were engaged in a conceptually focused (sentence verification) task (Experiment 1). Similarly, prospective remembering was lower following study-test changes in perceptual format (font) in the context of a perceptually focused (readability rating) ongoing task (Experiment 2). However, although dividing attention at retrieval had a negative effect during the performance of an ongoing conceptual task (Experiments 1 and 3), it had no effect during an ongoing perceptual task (Experiments 2 and 3). Thus, both perceptual and conceptual process are implicated in prospective remembering, but the processing focus of the task in which remembering should occur may mediate the requirement for strategic processes. These findings suggest that more than one retrieval route is available for prospective remembering and that selection of the route depends on the nature of the task and the processing that occurs at encoding and retrieval.

A comparison of conscious and automatic memory processes for picture and word stimuli: a process dissociation analysis

Four experiments were conducted to evaluate explanations of picture superiority effects previously found for several tasks. In a process dissociation procedure (Jacoby, 1991) with word stem completion, picture fragment completion, and category production tasks, conscious and automatic memory processes were compared for studied pictures and words with an independent retrieval model and a generate-source model. The predictions of a transfer appropriate processing account of picture superiority were tested and validated in "process pure" latent measures of conscious and unconscious, or automatic and source, memory processes. Results from both model fits verified that pictures had a conceptual (conscious/source) processing advantage over words for all tasks. The effects of perceptual (automatic/word generation) compatibility depended on task type, with pictorial tasks favoring pictures and linguistic tasks favoring words. Results show support for an explanation of the picture superiority effect that involves an interaction of encoding and retrieval processes.

Divided attention and prerecognition processing of spoken words and nonwords

Three recognition memory experiments examined phonemic similarity and false recognition under conditions of divided attention. The manipulation was presumed to have little effect on automatic, perceptual influences of memory. Prior research demonstrated that false recognition of a test word (e.g., discrepancy) was higher if the study list included a nonword derived from the future test word by changing a phoneme near the end of the item (e.g., discrepan/l/y) relative to an early phoneme change (e.g., /l/iscrepancy). The difference has been attributed to automatic, implicit activation of test words during prerecognition processing of related nonwords. Three experiments demonstrated that the late-change condition also contributed to higher false recognition rates with divided attention at encoding. Dividing attention disrupted recognition memory of studied words in Experiments 1 and 3. Results are discussed in terms of their relevance for an interpretation emphasizing the automatic, implicit activation of candidate words that occurs in the course of identifying spoken words and nonwords.

The implicit benefit of learning without errors

Two studies examined whether the number of errors made in learning a motor skill, golf putting, differentially influences the adoption of a selective (explicit) or unselective (implicit) learning mode. Errorful learners were expected to adopt an explicit, hypothesis-testing strategy to correct errors during learning, thereby accruing a pool of verbalizable rules and exhibiting performance breakdown under dual-task conditions, characteristic of a selective mode of learning. Reducing errors during learning was predicted to minimize the involvement of explicit hypothesis testing leading to the adoption of an unselective mode of learning, distinguished by few verbalizable rules and robust performance under secondary task loading. Both studies supported these predictions. The golf putting performance of errorless learners in both studies was unaffected by the imposition of a secondary task load, whereas the performance of errorful learners deteriorated. Reducing errors during learning limited the number of error-correcting hypotheses tested by the learner, thereby reducing the contribution of explicit processing to skill acquisition. It was concluded that the reduction of errors during learning encourages the use of implicit, unselective learning processes, which confer insusceptibility to performance breakdown under distraction.

The effects of attention on perceptual implicit memory

Reports on the effects of dividing attention at study on subsequent perceptual priming suggest that perceptual priming is generally unaffected by attentional manipulations as long as word identity is processed. We tested this hypothesis in three experiments by using the implicit word fragment completion and word stem completion tasks. Division of attention was instantiated with the Stroop task in order to ensure the processing of word identity even when the participant's attention was directed to a stimulus attribute other than the word itself. Under these conditions, we found that even though perceptual priming was significant, it was significantly reduced in magnitude. A stem cued recall test in Experiment 2 confirmed a more deleterious effect of divided attention on explicit memory. Taken together, our findings delineate the relative contributions of perceptual analysis and attentional processes in mediating perceptual priming on two ubiquitously used tasks of word fragment completion and word stem completion.

Implicit memory: intention and awareness revisited

One of the major developments in memory research in the past decade or so has been a growing interest in implicit memory - task performance that is not accompanied by conscious or intentional recollection. In this article, we examine evidence for perceptual and conceptual implicit memory, using the accepted definitions, and suggest that there is in fact a lack of strong evidence for implicit memory in normal subjects. If more convincing evidence cannot be obtained, one solution might be to modify the current terminology. We suggest that the term implicit memory might have outgrown its usefulness as an overall descriptor.