Stimulus meaningfulness and paired-associate transfer: an encoding variability hypothesis

Chinese character unitization enhances item memory in addition to associative memory: Evidence from ERP and TFR

While the effect of unitization on associative memory has been established, its effect on item memory remains debated. This study aimed to investigate the influence of unitization on item memory using Chinese characters to manipulate unitization and recording scalp EEG to elucidate the underlying neural mechanisms. In the learning phase, participants were asked to determine whether the character pairs presented could form a Chinese compound character. In the subsequent testing phase, participants performed item recognition and associative recognition tasks. Behavioral results revealed that unitization not only improved associative memory but also facilitated item memory. Event-related potential analysis indicated there were FN400 effect (related to familiarity) and LPC effect (related to recollection) during associative recognition after unitization, however, only the LPC effect was observed for the item recognition. More importantly, time-frequency analysis demonstrated stronger θ oscillations (associated with recollection) in the unitized condition compared to the non-unitized condition, which further partially mediated the reduction in RT during the item recognition. These results suggest that unitization enhances item memory through recollection, thereby leading to more confident recognition judgments, and that unitization does not impair item processing within an association but rather enables more precise and accurate processing.

Does taking multiple photos lead to a photo-taking-impairment effect?

The photo-taking-impairment effect is observed when photographed information is less likely to be remembered than nonphotographed information. Three experiments examined whether this effect persists when multiple photos are taken. Experiment 1 used a within-subjects laboratory-based design in which participants viewed images of paintings and were instructed to photograph them once, five times, or not at all. Participants' memory was measured using a visual detail test, and the photo-taking-impairment effect was observed when participants took multiple photos. Experiment 2 examined the photo-taking-impairment effect using a between-subjects design. Participants either photographed all of the paintings they saw once, five times, or not at all, before being tested on their memory for the paintings. The photo-taking-impairment effect was observed in both photo-taking conditions relative to the no photo baseline. Experiment 3 replicated this pattern of results even when participants who took multiple photos were instructed to take five unique photos. These findings indicate that the photo-taking-impairment effect is robust, occurring even when multiple photos are taken, and after nonselective photo-taking.

Predicting memory formation over multiple study episodes

Repeated study typically improves episodic memory performance. Two different types of explanations of this phenomenon have been put forward: (1) reactivating the same representations strengthens and stabilizes memories, or (2) greater encoding variability benefits memory by promoting richer traces. The present experiment directly compared these predictions in a design with multiple repeated study episodes, allowing to dissociate memory for studied items and their context of study. Participants repeatedly encoded names of famous people four times, either in the same task, or in different tasks. During the test phase, an old/new judgment task was used to assess item memory, followed by a source memory judgment about the encoding task. Consistent with predictions from the encoding variability view, encoding stimulus in different contexts resulted in higher item memory. In contrast, consistent with the reactivation view, source memory performance was higher when participants encoded stimuli in the same task repeatedly. Taken together, our findings indicate that encoding variability benefits episodic memory, by increasing the number of items that are recalled. These benefits are however at the expenses of source recollection and memory for details, which are decreased, likely due to interference and generalization across contexts.

Effects of Associative Reaction Time and Meaningfulness of Stimulus Terms in Forward and Backward Paired-Associate Learning

48 Ss learned a list of PAs, at either a 2-sec. or 7-sec. presentation rate (PR), in which the stimulus terms were assessed on the bases of associative reaction time (RT) and meaningfulness (M). In forward anticipation learning, the effect of RT of stimulus terms was not significant but M was, with the greatest effect at the 2-sec. PR. In a backward recall test, the short-latency RT stimulus terms were recalled more frequently than the long-latency RT terms and high-M terms were recalled more frequently than low-M terms. The results were interpreted in terms of a two-stage analysis in which the effects of M were related to stimulus recognition and the effects of RT to stimulus recall.

Latencies of Sexual and Asexual Responses to Double-Entendre Words as a Function of Sex-Guilt and Social Desirability in College Females

A restricted association procedure was used to study females' latencies associated with sexual and asexual responses to double-entendre sexual words. Latencies were also examined relative to two personality variables, sex-guilt and social desirability. The results indicated that sexual responses were accompanied by longer latencies than asexual responses. There was also an interaction between sex-guilt and sexual-asexual response latencies, with subjects of high sex-guilt showing longer latencies of sexual response but not of asexual response. Contrary to prediction, individual differences on the social desirability variable were unrelated to latencies of either sexual or asexual response. The study also outlined a stimulus-encoding model for associations to double-entendre sexual words.

Latencies of Restricted Associations to Double-Entendre Sexual Words as a Function of Personality Variables

Sexually avoidant and non-avoidant subjects as defined by the personality constructs of sex-guilt, social desirability, and repression-sensitization were required to give both sexual and asexual responses to the same set of sexual double-entendre words. With the exception of the repression-sensitization variable, the results were generally in the direction predicted from a stimulus-encoding analysis of the way in which subjects process sexual double-entendre words. In general, sexually avoidant subjects showed longer latencies than non-avoidant subjects when giving sexual responses but not on asexual responses. Likewise, sexual response latencies were significantly longer than asexual response latencies for sex-avoidant but not for sexually non-avoidant subjects. Sexual responses were also uniformly associated with longer latencies than asexual responses.

Trial-level information for individual faces in the fusiform face area depends on subsequent memory

Previous research has shown that face-sensitive brain regions, such as the fusiform face area (FFA) and anterior inferior temporal lobe (aIT), not only respond selectively to face stimuli, but also respond uniquely to individual faces. A common factor in the existing literature is that face stimuli in these experiments are highly familiar to participants, usually by design. We set out to investigate to what extent familiarity correlates with the emergence of face-specific information in face-sensitive regions by testing novel faces with only a single repetition. Our results, consistent with a familiarity hypothesis, demonstrate that the FFA and aIT show face-specific information only when participants demonstrate subsequent memory for those faces. Functionally-defined regions that are not believed to process faces holistically showed no face-specific information, regardless of subsequent memory. To our knowledge, this is the first demonstration of face-specific information in face-sensitive regions for stimuli that were not highly familiar. These results contribute to our understanding of how individuating information comes to be represented in face-sensitive regions and suggest that this process can take place even after a single repetition of a particular face.

Recency, repetition, and the multidimensional basis of recognition memory

Recency and repetition are two factors that have large effects on human memory performance. One way of viewing the beneficial impact of these variables on recognition memory is to assume that both factors modulate a unidimensional memory trace strength. Although previous functional neuroimaging studies have indicated that recency and repetition may modulate similar brain structures, particularly in the region of the inferior parietal cortex, there is extensive behavioral evidence that human subjects can make independent and accurate recognition memory judgments about both an item's recency and its frequency. In the present study, we used fMRI to examine patterns of brain activity during recognition memory for auditory-verbal stimuli that were parametrically and orthogonally manipulated in terms of recency and number of repetitions. We found in a continuous recognition paradigm that the lateral inferior parietal cortex, a region that has previously been associated with recollective forms of memory, is highly sensitive to recency but not repetition. In a multivariate analysis of whole-brain activation patterns, we found orthogonal components that dissociated recency and repetition variables, indicating largely independent neural bases underlying these two factors. The results demonstrate that although both recency and repetition dramatically improve recognition memory performance, the neural bases for this improvement are dissociable, and thus are difficult to explain in terms of access to a unitary memory trace.

Noninvasive functional and anatomical imaging of the human medial temporal lobe

The ability to remember life's events, and to leverage memory to guide behavior, defines who we are and is critical for everyday functioning. The neural mechanisms supporting such mnemonic experiences are multiprocess and multinetwork in nature, which creates challenges for studying them in humans and animals. Advances in noninvasive neuroimaging techniques have enabled the investigation of how specific neural structures and networks contribute to human memory at its many cognitive and mechanistic levels. In this review, we discuss how functional and anatomical imaging has provided novel insights into the types of information represented in, and the computations performed by, specific medial temporal lobe (MTL) regions, and we consider how interactions between the MTL and other cortical and subcortical structures influence what we learn and remember. By leveraging imaging, researchers have markedly advanced understanding of how the MTL subserves declarative memory and enables navigation of our physical and mental worlds.

All varieties of encoding variability are not created equal: Separating variable processing from variable tasks

Whether encoding variability facilitates memory is shown to depend on whether item-specific and relational processing are both performed across study blocks, and whether study items are weakly versus strongly related. Variable-processing groups studied a word list once using an item-specific task and once using a relational task. Variable-task groups' two different study tasks recruited the same type of processing each block. Repeated-task groups performed the same study task each block. Recall and recognition were greatest in the variable-processing group, but only with weakly related lists. A variable-processing benefit was also found when task-based processing and list-type processing were complementary (e.g., item-specific processing of a related list) rather than redundant (e.g., relational processing of a related list). That performing both item-specific and relational processing across trials, or within a trial, yields encoding-variability benefits may help reconcile decades of contradictory findings in this area.

Significance of autobiographical episodes and spacing effects in incidental memory

Participants were presented with target words on two occasions, and were asked each time to generate a memory of a past episode associated with the targets. Participants were also instructed to rate the importance (significance elaboration) or pleasantness of the pisode (pleasantness elaboration) in an orienting task, followed by an unexpect d recall test. Significance elaboration led to better recall than pleasantness elaboration, but only in the spaced presentation. The spaced presentation led to better tree recall than massed presentation with significance elaboration, but the difference between the two types of presentation was not observed with pleasantness elaboration. These results suggest that the significance of an episode is more critical than the pleasantness of an episode in determining the effectiveness of autobiographical elaboration in facilitating recall.

Acoustic-reward learning as a method to reduce the incidence of aggressive and abnormal behaviours among newly mixed piglets

The aim of the study was to test whether aggressive actions among piglets could be redirected by an automatically generated sound signal followed by a sweet food reward. Per round, four litters of 25-day-old piglets (BHZP breed) were trained 5 times per day over 8 days to expect a sweet feed reward from a dog feeder after hearing a specific sound. In total 144 piglets in 14 entire litters were trained in five trials. At the end of the training 71% of the piglets were around the feeder 5 s after the feeder sound. After the training period, the piglets were weaned and mixed in two pens, 12 piglets per pen. During 2 days (3 h/day) after mixing two observers (one per pen) hidden behind a wooden wall activated the feeder when aggressive or abnormal behaviour started. A total of 616 aggressive events and 31 incidences of abnormal behaviour (ear biting) were used for the analysis. The logistic regression showed that the type of behaviour had a significant effect on the piglets’ response to the feeder sound (P < 0.001). The results showed the possibility of interruption of the aggressive behaviours such as head thrust [odds ratio (OR) = 0.43], jump on other (OR = 0.56) or attack with bite (OR = 0.61). Ear biting was very unlikely to continue (OR = 0.55). The risk of continuing elevated aggression level behaviours was doubled in the event of chasing (OR = 2.16) and the risk that fight would continue after the feeder sound was released was 7 times higher (OR = 7.89). Categorical analysis showed a significant effect (<0.001) of the time intervals t ≤ 1 s and 1 s < t ≤ 3 s on interruption of aggression by the feeder sound release. The piglets’ response to the feeder sound differed significantly between the experimental days (P < 0.001). On the second day of mixing, the feeder sound interrupted 74.9% of aggressive events, compared with 33.7% on the first day. The results suggest that acoustic-reward treatment can distract pigs from performing certain aggressive behaviours and ear biting in piglets when properly applied in time.

Influence of Multiple-Day Temporal Distribution of Repetitions on Memory: A Comparison of Uniform, Expanding, and Contracting Schedules

Very few studies have examined the influence of schedules of repetitions across multiple days (e.g., Tsai, 1927). Three temporal schedules of four presentations of pseudoword/word pairs over a 7-day learning period were compared: a uniform (presentations on Days 1, 3, 5, and 7), an expanding (1, 2, 3, 7), and a contracting (1, 5, 6, 7) schedule. Schedule was a within-subjects variable. Experiment 1 was performed on the Internet and showed that cued recall on Day 9 led to higher scores for the stimuli of the expanding schedule. Experiment 2 was performed in the laboratory and showed that the expanding and the uniform schedules led to the highest scores on Day 9. A recognition task performed during the learning phase revealed that stimuli recognized at the time of their repetition were more likely to be retrieved later than the others. Our results are discussed within the framework of the study-phase retrieval and encoding variability theories.

Greater neural pattern similarity across repetitions is associated with better memory

Repeated study improves memory, but the underlying neural mechanisms of this improvement are not well understood. Using functional magnetic resonance imaging and representational similarity analysis of brain activity, we found that, compared with forgotten items, subsequently remembered faces and words showed greater similarity in neural activation across multiple study in many brain regions, including (but not limited to) the regions whose mean activities were correlated with subsequent memory. This result addresses a longstanding debate in the study of memory by showing that successful episodic memory encoding occurs when the same neural representations are more precisely reactivated across study episodes, rather than when patterns of activation are more variable across time.

The effect of a cross-trial shift of auditory warning signals on the sequential foreperiod effect

When a warning signal (WS) precedes an imperative signal (IS) by a certain amount of time (the foreperiod, FP), responses are speeded. Moreover, this effect is modulated by the FP length in the previous trial. This sequential FP effect has lately been attributed to a trace-conditioning mechanism according to which individuals learn (and re-learn) temporal relationships between the WS and the IS. Recent evidence suggests that sensory WS attributes are critical to trigger time-related response activation. Specifically, when WS modality is shifted in subsequent trials (e.g., from auditory to visual modality), the sequential FP effect becomes attenuated. This study examined whether the sequential FP effect is reduced only by between-modality shifts or whether this attenuation generalizes to cross-trial shifts of WS attributes within modalities. We compared dimensional (low vs. high tone frequency) and qualitative shifts (pure tone vs. noise) of equal-intense auditory WS events. The results of four experiments revealed that shifts of tone frequency did not, whereas shifts of qualitative tone characteristics did attenuate the sequential FP effect. These results support the view that the WS acts as a trigger cue that unintentionally activates responses at previously reinforced critical moments.

Is neocortical-hippocampal connectivity a better predictor of subsequent recollection than local increases in hippocampal activity? New insights on the role of priming

During memory encoding, increased hippocampal activity-thought to reflect the binding of different types of information into unique episodes-has been shown to correlate with subsequent recollection of those episodes. Repetition priming-thought to induce more efficient perceptual processing of stimuli-is normally associated with decreased neocortical activity and is often assumed to reduce encoding into episodic memory. Here, we used fMRI to compare activity to primed and unprimed auditory words in the presence of distracting sounds as a function of whether participants subsequently recollected the word-sound associations or only had a feeling of familiarity with the word in a subsequent surprise recognition task. At the behavioral level, priming increased the incidence of subsequent recollection. At the neuronal level, priming reduced activity in the superior temporal gyrus (STG) but also reversed the traditional increase in encoding-related hippocampal activity associated with subsequent recollection relative to subsequent familiarity. To explain this interaction pattern, further analyses using dynamic causal modeling showed an increase in connectivity from left STG to left hippocampus specific to words that were later recollected. These findings show that successful episodic encoding is not determined solely by local hippocampal activity and emphasize instead the importance of increased functional neocortical-hippocampal coupling. Such coupling might be a better predictor of subsequent recollection than the direction of local hippocampal changes per se. We propose that one consequence of priming is to "free up" attentional resources from processing an item in a noisy context, thereby allowing greater attention to encoding of that context.

Effects of the time dimension and presentation on incidental memory

Undergraduates were presented targets on two occasions, and each time they were asked to choose one of two alternatives (past or future) associated with the targets in the orienting task, followed by an unexpected free recall. For the pleasant targets, the spaced presentation led to a better recall than the massed presentation for both past and future time. However, for unpleasant targets, the spacing effect was found in recall of targets associated with the past but the effect was not observed in recall of targets associated with the future. These results were interpreted as indicating that the quantity and the quality of the episodes associated with the targets were processed differently as a function of emotional attribute and time dimension.

The phosphatase SHP2 regulates the spacing effect for long-term memory induction

A property of long-term memory (LTM) induction is the requirement for repeated training sessions spaced over time. This augmentation of memory formation with spaced resting intervals is called the spacing effect. We now show that in Drosophila, the duration of resting intervals required for inducing LTM is regulated by activity levels of the protein tyrosine phosphatase corkscrew (CSW). Overexpression of wild-type CSW in mushroom body neurons shortens the inter-trial interval required for LTM induction, whereas overexpression of constitutively active CSW proteins prolongs these resting intervals. These gain-of-function csw mutations are associated with a clinical condition of mental retardation. Biochemical analysis reveals that LTM-inducing training regimens generate repetitive waves of CSW-dependent MAPK activation, the length of which appears to define the duration of the resting interval. Constitutively active CSW proteins prolong the resting interval by altering the MAPK inactivation cycle. We thus provide insight into the molecular basis of the spacing effect.

Using Popular Films to Enhance Classroom Learning

Popular history films sometimes contain major historical inaccuracies. Two experiments investigated how watching such films influences people's ability to remember associated texts. Subjects watched film clips and studied texts about various historical topics. Whereas the texts contained only correct information, the film clips contained both correct information (consistent with the text) and misinformation (contradicted by the text). Before watching each clip, subjects received a specific warning, a general warning, or no warning about the misinformation. One week later, they returned for a cued-recall test about the texts. Watching a film clip increased correct recall of consistent information relative to recall of the same information when subjects did not see the clip. However, when the information in the film contradicted the text, subjects often (falsely) recalled misinformation from the film. The specific warning substantially reduced this misinformation effect. Teachers should use popular history films with caution and should warn students about major inaccuracies in the films.

List discrimination in associative recognition and implications for representation

Four experiments tested the predictions made by the model outlined in A. H. Criss and R. M. Shiffrin (2004b). Participants studied 2 successive lists of pairs followed by a recognition memory test for the most recent list. Some items and some pairs were repeated across the 2 lists. Critically, a given item could be repeated in the same or different type of pair. For associative recognition, performance was only affected by repetitions in the same pair type. However, in single-item recognition confusions occurred for both types of repetitions. The results are as predicted and confirm the assumption that different associative representations were stored even when the same token repeated in different pair types, whereas similar item representations were used regardless of pair type.

Encoding richness of self-generated elaboration and spacing effects on incidental memory

The present study investigated encoding variability in self-generated elaboration on incidental memory as a function of the type of presentation which was either massed or spaced. The subjects generated different answers to a "why" question for the first and the second presentations of a target sentence in a self-generated elaboration condition. In an experimenter-provided elaboration condition they then rated the appropriateness of the different answers provided by the experimenter for the first and second presentations. This procedure was followed by two free recall tests, one of which was immediate and the other delayed. A self-generated elaboration effect was observed in both the spaced and the massed presentations. These results indicated that the self-generated elaboration effect was facilitated, even in the massed presentation because the different answers to the first and the second presentations led to a richer encoding of each target.

Self-generated elaboration and spacing effects on incidental memory

The purpose of the present study was to investigate the effect of self-generated elaboration on incidental memory as a function of type of presentation (massed vs spacing). Subjects generated answers to "why" questions for target sentences in a self-generated elaboration condition. They then rated the appropriateness of the answers to the questions presented by the experimenter in an experimenter-provided elaboration condition. This procedure was followed by free recall tests. The target sentences were presented twice, in either a massed presentation without intervening items between the first and the second presentation or spaced presentation in which 5 items appeared between the two presentations. The self-generated elaboration effect, namely, higher recall, of self-generated elaboration over experimenter-provided elaboration, occurred with spaced but not with massed presentation. So, self-generated elaboration was facilitated in the spaced presentation because the time between the first and the second presentations led to richer encoding of each target.

Conceptual and perceptual novelty effects in human medial temporal cortex

Medial temporal lobe (MTL) structures often respond to stimulus repetition with a reduction in neural activity. Such novelty/familiarity responses reflect the mnemonic consequences of initial stimulus encounter, although the aspects of initial processing that lead to novelty/familiarity responses remain unspecified. The current functional magnetic resonance imaging (fMRI) experiment examined the sensitivity of MTL to changes in the semantic representations/processes engaged across stimulus repetitions. During initial study blocks, words were visually presented, and participants made size, shape, or composition judgments about the named referents. During repeated study blocks, the initial words were visually re-presented along with novel words, and participants made size judgments for all items. Behaviorally, responses were faster to repeated words in which the same task was performed at initial and repeated exposure (i.e., size-->size) relative to repeated words in which the tasks differed (i.e., composition-->size and shape-->size). fMRI measures revealed activation reductions in left parahippocampal cortex following same-task and different-task repetition; numerically, the effect was larger in the same-task condition. Accordingly, left parahippocampal cortex demonstrates sensitivity to perceptual novelty/familiarity, and it remains unclear whether this region also is sensitive to novelty/familiarity in the conceptual domain. In left perirhinal cortex, a novelty/familiarity effect was observed in the same-task condition but not in the different-task condition, thus revealing sensitivity to the degree of semantic overlap across exposures but insensitivity to perceptual repetition of the visual word form. Perirhinal sensitivity to semantic repetition and insensitivity to perceptual repetition suggests that human perirhinal cortex receives conceptual inputs, with perirhinal contributions to declarative memory perhaps partially stemming from its role in processing semantic aspects of experiences.

Implicit cognition and HIV risk behavior

Implicit cognition theory differs from most other approaches to health behavior in that it emphasizes neurobiologically plausible and experimentally documented memory association processes rather than rational decisions, considerations of pros and cons, or beliefs. The present study of adults from a community population investigated the predictive effects of implicit cognition, as well as behavioral and personality variables (sensation seeking, hostility, conscientiousness, and polydrug use), on risky sexual behaviors (lack of condom use, sex after drug use, and multiple sexual partners). In addition, this study simultaneously investigated the predictors in both a high-risk and a low-risk sample. Results showed that the implicit cognition indicator was a significant, independent predictor of lack of condom use in the high-risk sample. Polydrug use and sensation seeking also had important predictive effects. The results encourage more research on implicit cognition in health behavior and further document links among drug use, personality, and HIV risk behavior.

A multinomial modeling analysis of the recognition-failure paradigm

The recognition-failure paradigm has received much theoretical consideration, especially the Tulving-Wiseman function and its exceptions. We show that the Tulving-Wiseman function does a poor job of accounting for the data, both when its fit is measured with a model-based, goodness-of-fit statistic and when a logically equivalent reformulation of the function is compared with data. We then present a simple multinomial model based on retrieval-independence theory that is capable of measuring storage and retrieval processes in recognition failure. The model is used to conduct a meta-analysis of the recognition-failure paradigm, and shows that violations of the Tulving-Wiseman function occur under conditions in which weak storage is coupled with strong retrieval. In addition, if storage and retrieval are assumed to be positively correlated across conditions, the model produces a theoretically motivated, alternative equation to the Tulving-Wiseman function that provides a virtually identical fit to the data.

Aging and recognition memory: methodological and interpretive problems

The recognition memory and aging literature has been reviewed with the purpose of evaluating the notion that the elderly encode semantic information in a more variable manner than the young. Because of methodological, as well as interpretive problems, only a handful of the investigations may be given serious consideration. It is recommended that future investigators report hits, false alarms, sensitivity and response-bias measures. It is also recommended that a concerted effort be made to equate age groups for response bias, that complete details of experimental procedures be reported and that appropriate statistical tests be made.

Bilingual Recognition of Concrete and Abstract Sentences

Eight French-English bilinguals were presented two lists of sentences constructed from different scenarios. For some of the scenarios, the language of the sentences was constant but for others, varied. On a subsequent recognition test, subjects received three types of sentences: (a) some previously presented (literals), (b) some semantically related but not previously presented (recognitions), (c) some differing only in language of presentation (translations). For both abstract and concrete scenarios in which initial presentation was in one language subjects made significantly fewer false acceptances than correct acceptances. However, for concrete scenarios in which the initial language of presentation had varied subjects accepted as many translations as recognitions and as many recognitions as literals. With the abstract scenarios which varied in the language of initial presentation subjects accepted as many recognitions as literals and more translations than literals. The results were interpreted in terms of the principle of variability of encoding.