Item Repetition Research Articles

P2-19: The Effect of item Repetition on Item-Context Association Depends on the Prior Exposure of Items

Previous studies have reported conflicting findings on whether item repetition has beneficial or detrimental effects on source memory. To reconcile such contradictions, we investigated whether the degree of pre-exposure of items can be a potential modulating factor. The experimental procedures spanned two consecutive days. On Day 1, participants were exposed to a set of unfamiliar faces. On Day 2, the same faces presented on the previous day were used again in half of the participants, whereas novel faces were used for the other half. Day 2 procedures consisted of three successive phases: item repetition, source association, and source memory test. In the item repetition phase, half of the face stimuli were repeatedly presented while participants were making male/female judgments. During the source association phase, both the repeated and the unrepeated faces appeared in one of the four locations on the screen. Finally, participants were tested on the location in which a given face was presented during th...

Mechanisms Driving Item Repetition Effects

Mechanisms Driving Item Repetition Effects

Pre-experimental familiarity modulates the effects of item repetition on source memory

Pre-experimental familiarity modulates the effects of item repetition on source memory

Neural Repetition Effects in the Medial Temporal Lobe Complex are Modulated by Previous Encoding Experience

It remains an intriguing question why the medial temporal lobe (MTL) can display either attenuation or enhancement of neural activity following repetition of previously studied items. To isolate the role of encoding experience itself, we assessed neural repetition effects in the absence of any ongoing task demand or intentional orientation to retrieve. Experiment 1 showed that the hippocampus and surrounding MTL regions displayed neural repetition suppression (RS) upon repetition of past items that were merely attended during an earlier study phase but this was not the case following re-occurrence of items that had been encoded into working memory (WM). In this latter case a trend toward neural repetition enhancement (RE) was observed, though this was highly variable across individuals. Interestingly, participants with a higher degree of neural RE in the MTL complex displayed higher memory sensitivity in a later, surprise recognition test. Experiment 2 showed that massive exposure at encoding effected a change in the neural architecture supporting incidental repetition effects, with regions of the posterior parietal and ventral-frontal cortex in addition to the hippocampus displaying neural RE, while no neural RS was observed. The nature of encoding experience therefore modulates the expression of neural repetition effects in the MTL and the neocortex in the absence of memory goals.

On optimality-ratio and coverage in ranking of joined search results

In complex search tasks, it is often required to pose several basic search queries, join the answers to these queries, where each answer is given as a ranked list of items, and return a ranked list of combinations. However, the join result may include too many repetitions of items, and hence, frequently the entire join is too large to be useful. This can be solved by choosing a small subset of the join result. The focus of this paper is on how to choose this subset. We propose two measures for estimating the quality of result sets, namely, coverage and optimality ratio. Intuitively, maximizing the coverage aims at including in the result as many as possible appearances of items in their optimal combination, and maximizing the optimality ratio means striving to have each item appearing only in its optimal combination, i.e., only in the most highly ranked combination that contains it. One of the difficulties, when choosing the subset of the join in a complex search, is that there is a conflict between maximizing the coverage and maximizing the optimality ratio. In this paper, we introduce the measures coverage and optimality ratio. We present new semantics for complex search queries, aiming at providing high coverage and high optimality ratio. We examine the quality of the results of existing and the novel semantics, according to these two measures, and we provide algorithms for answering complex search queries under the new semantics. Finally, we present an experimental study, using Yahoo! Local Search Web Services, of the efficiency and the scalability of our algorithms, showing that complex search queries can be evaluated effectively under the proposed semantics.

Negative effects of item repetition on source memory

In the present study, we explored how item repetition affects source memory for new item-feature associations (picture-location or picture-color). We presented line drawings varying numbers of times in Phase 1. In Phase 2, each drawing was presented once with a critical new feature. In Phase 3, we tested memory for the new source feature of each item from Phase 2. Experiments 1 and 2 demonstrated and replicated the negative effects of item repetition on incidental source memory. Prior item repetition also had a negative effect on source memory when different source dimensions were used in Phases 1 and 2 (Experiment 3) and when participants were explicitly instructed to learn source information in Phase 2 (Experiments 4 and 5). Importantly, when the order between Phases 1 and 2 was reversed, such that item repetition occurred after the encoding of critical item-source combinations, item repetition no longer affected source memory (Experiment 6). Overall, our findings did not support predictions based on item predifferentiation, within-dimension source interference, or general interference from multiple traces of an item. Rather, the findings were consistent with the idea that prior item repetition reduces attention to subsequent presentations of the item, decreasing the likelihood that critical item-source associations will be encoded.

Lexical Cohesion: An Issue only in the Foreign Language?

The purpose of this study was to investigate Turkish EFL learners’ ability in composing cohesive texts in their first language and in English as their foreign language, and to examine whether there are similarities between lexical reiteration cohesive devices they employ in composing cohesive texts both in Turkish and in English. The study was conducted with the participation of 40 students. The data of the study came from written accounts of a story in both languages based on a set of pictures with eight episodes. The analysis of the data has revealed striking similarities between English and Turkish in terms of the employment of lexical reiteration cohesive devices. The results have shown that repetition of the same lexical items was by far the most frequently used type of lexical cohesion in both languages. The findings are discussed in terms of their implications for writing.

Versatile perceptual learning of textures after variable exposures

Perceptual learning of 10-AFC texture identification is stimulus specific: after practice, identification accuracy drops substantially when textures are rotated 180°, reversed in contrast polarity, or when a novel set of textures is presented. Here we asked if perceptual learning occurs without any repetition of items during training, and whether exposure to greater stimulus variation during training influences transfer of learning. We trained three groups of subjects in a 10-AFC texture identification task on 2days. The Standard group viewed a fixed set of 10 textures throughout training. The Variable group viewed 840 novel sets of textures. The Switch group viewed different fixed sets of 10 textures on Days 1 and 2. In all groups, transfer of learning was tested by using fixed sets of textures on Days 3 and 4 and having half of the subjects from each group switch to a novel set on Day 4. During training, the most learning was obtained by the Standard group, and gradual but significant learning was obtained by the other two groups. On Day 4, performance of the Standard group was adversely affected by a switch to novel textures, whereas performance of the Variable and Switch groups remained intact. Hence, slight but significant learning occurred without repetition of items during training, and stimulus specificity was influenced significantly by the type of training. Increasing stimulus variability by reducing the number of times stimuli are repeated during practice may cause subjects to adopt strategies that increase generalization of learning to new stimuli. Alternatively, presenting new stimuli on each trial may prevent subjects from adopting strategies that result in stimulus specific learning.

Repetition enhancement and perceptual processing of visual word form

The current study investigated the cerebral basis of word perceptual repetition priming with fMRI during a letter detection task that manipulated the familiarity of perceptual word form and the number of repetitions. Some neuroimaging studies have reported increases, instead of decreases, in brain activations (called “repetition enhancement”) associated with repetition priming of unfamiliar stimuli which have been interpreted as the creation of new perceptual representations for unfamiliar items. According to this interpretation, several repetitions of unfamiliar items would then be necessary for the repetition priming to occur, a hypothesis not explicitly tested in prior studies. In the present study, using a letter detection task on briefly flashed words, we explored the effect of familiarity on brain response for word visual perceptual priming using both words with usual (i.e., familiar) and unusual (i.e., unfamiliar) font, presented up to four times for stimuli with unusual font. This allows potential changes in the brain responses for unfamiliar items to be assessed over several repetitions, i.e., repetition enhancement to suppression. Our results reveal significant increases of activity in the bilateral occipital areas related to repetition of words in both familiar and unfamiliar conditions. Our findings support the sharpening hypothesis, showing a lack of cerebral economy with repetition when the task requires the processing of all word features, whatever the familiarity of the material, and emphasize the influence of the nature of stimuli processing on its neuronal manifestation.

Visual search for arbitrary objects in real scenes

How efficient is visual search in real scenes? In searches for targets among arrays of randomly placed distractors, efficiency is often indexed by the slope of the reaction time (RT) × Set Size function. However, it may be impossible to define set size for real scenes. As an approximation, we hand-labeled 100 indoor scenes and used the number of labeled regions as a surrogate for set size. In Experiment 1, observers searched for named objects (a chair, bowl, etc.). With set size defined as the number of labeled regions, search was very efficient (~5ms/item). When we controlled for a possible guessing strategy in Experiment 2, slopes increased somewhat (~15ms/item), but they were much shallower than search for a random object among other distinctive objects outside of a scene setting (Exp. 3: ~40ms/item). In Experiments 4-6, observers searched repeatedly through the same scene for different objects. Increased familiarity with scenes had modest effects on RTs, while repetition of target items had large effects (>500ms). We propose that visual search in scenes is efficient because scene-specific forms of attentional guidance can eliminate most regions from the "functional set size" of items that could possibly be the target.

Recollection-related hippocampal activity during continuous recognition: a high-resolution fMRI study.

We used high-resolution functional magnetic resonance imaging to investigate whether successful recollection during continuous recognition is associated with relative enhancement of hippocampal activity, consistent with prior findings from experiments employing separate study and test phases. While being scanned, subjects discriminated between new and repeated pictures. Each picture, which was repeated once after an interval of between 10 and 30 items, was surrounded by a frame that was colored gray, blue, or orange. When an item repeated, its frame color determined the correct response. Repeated items surrounded by a gray frame always required an "old" judgment. A repeated item surrounded by a blue or an orange frame required a different response depending whether it was represented in the same (Target) or a different (Nontarget) color from the first presentation. Consistent with the results from previous continuous recognition experiments, robust new > old effects were found in bilateral hippocampus. In addition, an across-subjects correlational analysis identified a cluster of voxels in right hippocampus where recollection-related activity (operationalized by the contrast between correctly vs. incorrectly judged Nontargets) was positively correlated with recollection performance. Thus, successful recollection during continuous recognition is associated with a relative enhancement of hippocampal activity.

The effects of pure pair repetition on younger and older adults' associative memory.

Although aging causes relatively minor impairment in recognition memory for components, older adults' ability to remember associations between components is typically significantly compromised, relative to that of younger adults. This pattern could be associated with older adults' relatively intact familiarity, which helps preserve component memory, coupled with a marked decline in recollection, which leads to a decline in associative memory. The purpose of the current study is to explore possible methods that allow older adults to rely on pair familiarity in order to improve their associative memory performance. Participants in 2 experiments were repeatedly presented with either single items or pairings of items prior to a study list so that the items and the pairs were already familiar during the study phase. Pure pair repetition (the effects of pair repetition after the effects of item repetition are taken into account) increased associative memory for older and younger adults. Findings based on remember and know judgments suggest that familiarity but not recollection is involved in mediating the repetition effect.

Testing the limits of testing effects using completion tests

Recent work on testing effects has shown that retrieval practice can facilitate memory even for complex prose materials (Roediger & Karpicke, 2006a, 2006b). In three experiments the current study explores the effectiveness of retrieval practice on fill-in-the-blank (FITB) tests requiring the recall of specific words or phrases from a text. Final tests included both repeated items that were directly taken from initial tests, and related items. In Experiment 1, with a 2-day delay between initial and final tests, FITB testing benefited performance only on repeated items. In Experiment 2 a 7-day delay between testing sessions led to more robust effects on repeated items. However, once again no benefits were seen for related items. In Experiment 3 the scope of retrieval was varied by comparing FITB tests to paragraph recall tests requiring retrieval of all sentences following a topic sentence. Only the more open-ended recall practice demonstrated improvements in transfer to novel questions. The results suggest that scope or type of processing required during retrieval practice is likely a critical factor in whether testing will have specific or robust benefits.

The Neural Substrates of Recognition Memory for Verbal Information: Spanning the Divide between Short- and Long-term Memory

One of the classic categorical divisions in the history of memory research is that between short-term and long-term memory. Indeed, because memory for the immediate past (a few seconds) and memory for the relatively more remote past (several seconds and beyond) are assumed to rely on distinct neural systems, more often than not, memory research has focused either on short- (or "working memory") or on long-term memory. Using an auditory-verbal continuous recognition paradigm designed for fMRI, we examined how the neural signatures of recognition memory change across an interval of time (from 2.5 to 30 sec) that spans this hypothetical division between short- and long-term memory. The results revealed that activity during successful auditory-verbal item recognition in inferior parietal cortex and the posterior superior temporal lobe was maximal for early lags, whereas, conversely, activity in the left inferior frontal gyrus increased as a function of lag. Taken together, the results reveal that as the interval between item repetitions increases, there is a shift in the distribution of memory-related activity that moves from posterior temporo-parietal cortex (lags 1-4) to inferior frontal regions (lags 5-10), indicating that as time advances, the burden of recognition memory is increasingly placed on top-down retrieval mechanisms that are mediated by structures in inferior frontal cortex.

Oral counselling on dispensed medication: a survey of its extent and associated factors in a random sample of community pharmacies

Abstract To establish the current rate of oral counselling on dispensed medications, a random sample of 50 community pharmacists from the greater London area was selected. A non-participant observational method was used to obtain the required information. It was found that most pharmacist characteristics, including age, experience and employment status (proprietor, manager or locum) did not affect the rate of provision of oral counselling. However, the rate varied according to sex, with female pharmacists advising more patients. The rate of counselling was also influenced by the patient's age, the type of prescription (National Health Service or private), whether the prescription was a repeat or for new medication and the therapeutic category of the medicine. During the study, the collection of 1,472 prescription items was observed. Overall, counselling was provided for 39 per cent of patients. Counselling was given for around 70 per cent of new prescription items and for 20 per cent of repeat items.

Sublexical Effects on Eye Movements During Repeated Reading of Words and Pseudowords in Finnish

the role of different orthographic units (letters, syllables, words) in reading of orthographically transparent finnish language was studied by independently manipulating the number of letters (nol) and syllables (noS) in words and pseudowords and by recording eye movements during repeated reading aloud of these items. fluent adult readers showed evidence for using larger orthographic units in (pseudo)word recoding, whereas dysfluent children seem to be stuck in a letter-based decoding strategy, as lexicality and item repetition decreased the nol effect only among adult readers. the noS manipulation produced weak repetition effects in both groups. however, dysfluent children showed evidence for word-specific knowledge by making fewer fixations on words than pseudowords; moreover, repetition effects were more noticeable for words than pseudowords, as indexed by shortened average fixation durations on words due to item repetition. the number of fixations was generally reduced by repetition among dysfluent children, suggesting familiarity-based benefits perhaps at the perceptual level of processing.

Conversational role influences speech imitation

This study assessed the impact of a conscious imitation goal on phonetic convergence during conversational interaction. Twelve pairs of unacquainted talkers participated in a conversational task designed to elicit between-talker repetitions of the same lexical items. To assess the degree to which the talkers exhibited phonetic convergence during the conversational task, these repetitions were used to elicit perceptual similarity judgments provided by separate sets of listeners. In addition, perceptual measures of phonetic convergence were compared with measures of articulation rates and vowel formants. The sex of the pair of talkers and a talker's role influenced the degree of phonetic convergence, and perceptual judgments of phonetic convergence were not consistently related to individual acoustic-phonetic attributes. Therefore, even with a conscious imitative goal, situational factors were shown to retain a strong influence on phonetic form in conversational interaction.

Dissociation of the electrophysiological correlates of familiarity strength and item repetition

Event-related potentials (ERPs) were employed to investigate the relationship between the familiarity strength of recognition memory test items (pictures of animate and inanimate objects) and a putative ERP correlate of familiarity, the mid-frontal ‘old/new’ effect. A modified Remember/Know task was used in which subjects endorsed items as ‘remembered’ if any detail of the study presentation could be retrieved and, if not, judged the old/new status of the item using a 4-point confidence scale (‘confident old’ to ‘confident new’). Studied test items elicited a mid-frontal old/new effect that varied according to the rated familiarity of the eliciting item. Thus, prior findings that the mid-frontal effect is graded according to familiarity strength are not attributable to the confounding influence of study status, as has been suggested. ERPs elicited by studied and unstudied items that were rated equally familiar differed in the same latency range as that occupied by the mid-frontal old/new effect. Furthermore, the scalp topography of this repetition effect differed significantly from the topography of the mid-frontal effect. The findings suggest that ERPs elicited by recognition memory test items are modulated during the 300–500 ms latency range both by the familiarity strength of the item and, separately, by an implicit memory process that acts independently of the processes supporting familiarity-driven recognition judgments.

Implicit and explicit effects of frequency on judgments of recency

There is general agreement that repetition enhances various kinds of memory performance, but it remains unclear how repetition of identical items affects judgments of recency (JOR). The present study examined implicit repetition effects on JOR and the relationship between JOR and explicit judgments of frequency (JOF). Participants learned three lists consisting of 13 items, some of which were repeated from once to four times, and after learning each list, they judged how many times each list item was presented. Only after learning all three lists, participants could recognize the number of lists, and were asked to perform a temporal list discrimination task. The results showed that there was no significant effect of repetition on the accuracy of list discrimination but the response times for the most frequent items were significantly shorter. The results also showed a significant positive correlation between the accuracy of list discrimination and of JOF. These results suggest that higher frequency does not improve the accuracy of JOR, but intensifies the sense of easiness for the judgments, and that the ability to judge frequency contributes to JOR.

Behavioral, neuroimaging, and computational evidence for perceptual caching in repetition priming

Repetition priming (RP) is a form of learning, whereby classification or identification performance is improved with item repetition. Various theories have been proposed to understand the basis of RP, including alterations in the representation of an object and associative stimulus–response bindings. There remain several aspects of RP that are still poorly understood, and it is unclear whether previous theories only apply to well-established object representations. This paper integrates behavioral, neuroimaging, and computational modeling experiments in a new RP study using novel objects. Behavioral and neuroimaging results were inconsistent with existing theories of RP, thus a new perceptual memory-based caching mechanism is formalized using computational modeling. The model instantiates a viable neural mechanism that not only accounts for the pattern seen in this experiment but also provides a plausible explanation for previous results that demonstrated residual priming after associative linkages were disrupted. Altogether, the current work helps advance our understanding of how brain utilizes repetition for faster information processing.