Long-term Memory Representations Research Articles

The cognitive representation of a throwing technique in judo experts – Technological ways for individual skill diagnostics in high-performance sports

Objectives The paper addresses the cognitive skill representation of a judo technique and presents two examples on how to measure and interpret individual skill profiles based on these representations in high-performance sports. Method The cognitive skill representation of a throwing technique in high-level judo experts was tested with the Structure Dimension Analysis - Motorics (SDA-M). This method provides psychometric data on the mental structure and feature dimensions of movement representations in long-term memory. The cognitive units of such representation structures are so-called basic action concepts (BACs), which correspond to functionally meaningful body postures and sub-movements. Participants performed a hierarchical distance scaling (splitting task), in which they sorted a list of BACs according to their functional relevance in movement execution. Through a hierarchical cluster analysis, the SDA-M uncovered the cognitive structures of the throwing technique in participant’s long-term memory, and enabled the assessment of group and individual representations. Results Expert skill representations were organized in a distinctive hierarchical tree-like structure, which matched the functional and biomechanical demands of the task well. Also, insights about specific movement problems could be gained for two experts after assessing their individual structures. Conclusions The SDA-M method can be used as a diagnostic tool to measure individual skill representations, which helps to improve performance-related instructions and to optimize technical training routines in high-performance sports.

The role of semantic memory in short-term recall: Effect of strategic retrieval ability in an elderly population

ABSTRACT The present paper examines the relationship between two classic phenomena: semantic effects in short-term recall (STR) tasks, which are interpreted as indicating the involvement of long-term memory (LTM) in the functioning of short-term memory, on the one hand, and the existence of individual differences amongst elderly people in strategic retrieval ability (i.e., the ability to activate representations in LTM in a controlled way) on the other hand. Forty elderly participants completed a STR task under four different conditions which were thought to differentially involve LTM representations. Several executive functions, among which the strategic retrieval ability, were evaluated. The results showed that the participants who obtained the best performances in terms of strategic retrieval ability, and only in this executive ability, also exhibited better performances in the STR task, in particular when this task was performed under conditions which favored the use of LTM.

Accessing long-term memory representations during visual change detection

In visual change detection tasks, providing a cue to the change location concurrent with the test image (post-cue) can improve performance, suggesting that, without a cue, not all encoded representations are automatically accessed. Our studies examined the possibility that post-cues can encourage the retrieval of representations stored in long-term memory (LTM). Participants detected changes in images composed of familiar objects. Performance was better when the cue directed attention to the post-change object. Supporting the role of LTM in the cue effect, the effect was similar regardless of whether the cue was presented during the inter-stimulus interval, concurrent with the onset of the test image, or after the onset of the test image. Furthermore, the post-cue effect and LTM performance were similarly influenced by encoding time. These findings demonstrate that monitoring the visual world for changes does not automatically engage LTM retrieval.

Scene Memory Is More Detailed Than You Think

Observers can store thousands of object images in visual long-term memory with high fidelity, but the fidelity of scene representations in long-term memory is not known. Here, we probed scene-representation fidelity by varying the number of studied exemplars in different scene categories and testing memory using exemplar-level foils. Observers viewed thousands of scenes over 5.5 hr and then completed a series of forced-choice tests. Memory performance was high, even with up to 64 scenes from the same category in memory. Moreover, there was only a 2% decrease in accuracy for each doubling of the number of studied scene exemplars. Surprisingly, this degree of categorical interference was similar to the degree previously demonstrated for object memory. Thus, although scenes have often been defined as a superset of objects, our results suggest that scenes and objects may be entities at a similar level of abstraction in visual long-term memory.

Conceptual distinctiveness supports detailed visual long-term memory for real-world objects.

Humans have a massive capacity to store detailed information in visual long-term memory. The present studies explored the fidelity of these visual long-term memory representations and examined how conceptual and perceptual features of object categories support this capacity. Observers viewed 2,800 object images with a different number of exemplars presented from each category. At test, observers indicated which of 2 exemplars they had previously studied. Memory performance was high and remained quite high (82% accuracy) with 16 exemplars from a category in memory, demonstrating a large memory capacity for object exemplars. However, memory performance decreased as more exemplars were held in memory, implying systematic categorical interference. Object categories with conceptually distinctive exemplars showed less interference in memory as the number of exemplars increased. Interference in memory was not predicted by the perceptual distinctiveness of exemplars from an object category, though these perceptual measures predicted visual search rates for an object target among exemplars. These data provide evidence that observers' capacity to remember visual information in long-term memory depends more on conceptual structure than perceptual distinctiveness.

Long-term visual associations affect attentional guidance

When observers perform a visual search task, they are assumed to adopt an attentional set for what they are looking for. The present experiment investigates the influence of long-term visual memory associations on this attentional set. On each trial, observers were asked to search a display for a grayscale version of a known traffic sign. On each trial, a distractor sign was drawn in full color. This color could either be related or unrelated to the target sign. Distractors interfered more with search when their color was related (e.g. red when the target was a stop sign), implying that long-term color associations resulted in inadvertent attentional guidance, even though color was irrelevant to the task. The results add to the growing body of evidence that long-term memory representations automatically affect attentional orienting.

Are Representations in Working Memory Distinct From Representations in Long-Term Memory?

Neural activation in a 12-item probe-recognition task was examined to investigate the contribution of the hippocampus to long-term memory (LTM) retrieval and working memory (WM) retrieval. Results indicated a dissociation between the last item that participants studied and other items of the study list: Compared with all other serial positions, activation was reduced for the item in the most recent position (for which no items intervened between study and test). This finding suggests that this last item was in focal attention at test time, and, therefore, no retrieval operation was required to access it. However, contra the assertion that the hippocampus should selectively support LTM, activation of the medial temporal lobe was observed for all serial positions other than the last position, and activation level could be predicted from the underlying memory strength. Collectively, these findings support single-store accounts that assume there are similar operating principles across WM and LTM representations, and the focus of attention is limited.

The episodic buffer in children with intellectual disabilities: An exploratory study

Performance on three verbal measures (story recall, paired associated learning, category fluency) designed to assess the integration of long-term semantic and linguistic knowledge, phonological working memory and executive resources within the proposed ‘episodic buffer’ of working memory (Baddeley, 2007) was assessed in children with intellectual disabilities (ID). It was hypothesised that children with ID would show equivalent performance to typically developing children of the same mental age. This prediction was based on the hypothesis that, despite poorer phonological short-term memory than mental age matched peers, those with ID may benefit from more elaborate long-term memory representations, because of greater life experience. Children with ID were as able as mental age matched peers to remember stories, associate pairs of words together and generate appropriate items in a category fluency task. Performance did not, however, reach chronological age level on any of the tasks. The results suggest children with ID perform at mental age level on verbal ‘episodic buffer’ tasks, which require integration of information from difference sources, supporting a ‘delayed’ rather than ‘different’ view of their development.

Training the Brain to Weight Speech Cues Differently: A Study of Finnish Second-language Users of English

Foreign-language learning is a prime example of a task that entails perceptual learning. The correct comprehension of foreign-language speech requires the correct recognition of speech sounds. The most difficult speech-sound contrasts for foreign-language learners often are the ones that have multiple phonetic cues, especially if the cues are weighted differently in the foreign and native languages. The present study aimed to determine whether non-native-like cue weighting could be changed by using phonetic training. Before the training, we compared the use of spectral and duration cues of English /i/ and /I/ vowels (e.g., beat vs. bit) between native Finnish and English speakers. In Finnish, duration is used phonologically to separate short and long phonemes, and therefore Finns were expected to weight duration cues more than native English speakers. The cross-linguistic differences and training effects were investigated with behavioral and electrophysiological methods, in particular by measuring the MMN brain response that has been used to probe long-term memory representations for speech sounds. The behavioral results suggested that before the training, the Finns indeed relied more on duration in vowel recognition than the native English speakers did. After the training, however, the Finns were able to use the spectral cues of the vowels more reliably than before. Accordingly, the MMN brain responses revealed that the training had enhanced the Finns' ability to preattentively process the spectral cues of the English vowels. This suggests that as a result of training, plastic changes had occurred in the weighting of phonetic cues at early processing stages in the cortex.

Single‐digit arithmetic in children with dyslexia

It has been suggested that individuals with dyslexia show poorer performance on those aspects of arithmetic that involve the manipulation of verbal representations, such as the use of fact retrieval strategies. The present study examined this in 13 children with dyslexia who showed normal general mathematics achievement and 16 matched controls. All children completed a multiplication and a subtraction task, which were specifically designed to elicit the use of retrieval and procedural strategies, respectively. Our findings revealed that despite normal mathematics achievement, children with dyslexia were less accurate and slower in single-digit arithmetic, particularly in multiplication. The reaction time data revealed an interesting group by operation interaction. Control children were significantly faster in multiplication than in subtraction, whereas no such operation effect was found in children with dyslexia. This suggests that in multiplication children with dyslexia used less retrieval or less efficient retrieval (or both). This is in line with the hypothesis that children with dyslexia may have difficulties with the verbal aspects of number and arithmetic, as retrieval strategies depend upon phonological representations in long-term memory.

Altered evoked gamma-band responses reveal impaired early visual processing in ADHD children

Neurophysiological studies yield contrary results whether attentional problems of patients with attention-deficit/hyperactivity disorder (ADHD) are related to early visual processing deficits or not. Evoked gamma-band responses (GBRs), being among the first cortical responses occurring as early as 90 ms after visual stimulation in human EEG, have been assigned a pivotal role in early visual processing. In particular, they are involved in memory matching processes and are enhanced when known stimuli are processed. The current study examined whether evoked GBR patterns during early memory matching processes could be indicative of an early visual processing deficit in ADHD patients. EEG was recorded from 13 young ADHD patients as well as 13 age-matched healthy participants. Both groups performed a simple forced choice reaction task employing line drawings of either known real-world items with representations in long-term memory or physically similar unknown items without such representations. Evoked GBRs of ADHD patients did not differentiate between known and unknown items. However, in healthy children, evoked GBRs were enhanced when stimuli matched a representation stored in memory. This finding indicates disadvantages at early visual processing stages in ADHD patients: In contrast to healthy participants, ADHD children lack an early memory based classification, possibly resulting in an impaired ability to rapidly reallocate attentional resources to relevant stimuli. These findings suggest that impaired early automatic stimulus classification in ADHD patients could be involved in deficits of selective and sustained attention.

The high fidelity of scene representation in visual long-term memory

The high fidelity of scene representation in visual long-term memory

Comparing the fidelity of perception, short-term memory, and long-term memory: Evidence for highly detailed long-term memory representations

Comparing the fidelity of perception, short-term memory, and long-term memory: Evidence for highly detailed long-term memory representations

Audiovisual Functional Magnetic Resonance Imaging Adaptation Reveals Multisensory Integration Effects in Object-Related Sensory Cortices

Information integration across different sensory modalities contributes to object recognition, the generation of associations and long-term memory representations. Here, we used functional magnetic resonance imaging adaptation to investigate the presence of sensory integrative effects at cortical levels as early as nonprimary auditory and extrastriate visual cortices, which are implicated in intermediate stages of object processing. Stimulation consisted of an adapting audiovisual stimulus S(1) and a subsequent stimulus S(2) from the same basic-level category (e.g., cat). The stimuli were carefully balanced with respect to stimulus complexity and semantic congruency and presented in four experimental conditions: (1) the same image and vocalization for S(1) and S(2), (2) the same image and a different vocalization, (3) different images and the same vocalization, or (4) different images and vocalizations. This two-by-two factorial design allowed us to assess the contributions of auditory and visual stimulus repetitions and changes in a statistically orthogonal manner. Responses in visual regions of right fusiform gyrus and right lateral occipital cortex were reduced for repeated visual stimuli (repetition suppression). Surprisingly, left lateral occipital cortex showed stronger responses to repeated auditory stimuli (repetition enhancement). Similarly, auditory regions of interest of the right middle superior temporal gyrus and sulcus exhibited repetition suppression to auditory repetitions and repetition enhancement to visual repetitions. Our findings of crossmodal repetition-related effects in cortices of the respective other sensory modality add to the emerging view that in human subjects sensory integrative mechanisms operate on earlier cortical processing levels than previously assumed.

Visuospatial cues for reinstating mental models in working memory during interrupted reading.

Reading involves constructing a mental representation in long-term working memory of the world described by the text. Disrupting short-term working memory can interfere with the maintenance of mental models (sets of retrieval cues) needed to access these representations, producing detrimental effects on reading time. In two experiments, subjects read passages that included pairs of coreferential sentences interrupted by unrelated text. As in previous research, reading times increased for the first sentence after the interruption, likely reflecting a reinstatement process for mental models in working memory. In the present research, pictures were provided as visuospatial cues to aid the reinstatement process. The interruption effect was found to be smaller with pictures related to the passages than with unrelated pictures (Experiment 1) or titles (Experiment 2); however, both of these effects occurred only for slow readers. The authors hypothesize that slow readers take the time needed to integrate visuospatial information into their mental models, providing more resilient access to long-term working memory.

There are Multiple Contributors to the Verbal Short-Term Memory Deficit in Children with Developmental Reading Disabilities

Prior research has put forth at least four possible contributors to the verbal short-term memory (VSTM) deficit in children with developmental reading disabilities (RD): poor phonological awareness that affects phonological coding into VSTM, a less effective phonological store, slow articulation rate, and fewer/poorer quality long-term memory (LTM) representations. This project is among the first to test the four suppositions in one study. Participants included 18 children with RD and 18 controls. VSTM was assessed using Baddeley's model of the phonological loop. Findings suggest all four suppositions are correct, depending upon the type of material utilized. Children with RD performed comparably to controls in VSTM for common words but worse for less frequent words and nonwords. Furthermore, only articulation rate predicted VSTM for common words, whereas Verbal IQ and articulation rate predicted VSTM for less frequent words, and phonological awareness and articulation rate predicted VSTM for nonwords. Overall, findings suggest that the mechanism(s) used to code and store items by their meaning is intact in RD, and the deficit in VSTM for less frequent words may be a result of fewer/poorer quality LTM representations for these words. In contrast, phonological awareness and the phonological store are impaired, affecting VSTM for items that are coded phonetically. Slow articulation rate likely affects VSTM for most material when present. When assessing reading performance, VSTM predicted decoding skill but not word identification after controlling Verbal IQ and phonological awareness. Thus, VSTM likely contributes to reading ability when words are novel and must be decoded.

Formation of Long-Term Memory Representation in Human Temporal Cortex Related to Pictorial Paired Associates

It is widely held that long-term memory gradually develops in the temporal neocortex after initial memory encoding into the hippocampus. However, little is known as to whether and where long-term memory can be newly created in the human temporal neocortex. In this functional magnetic resonance imaging study, we detected brain activity in the temporal neocortex that was developed approximately 8 weeks after study of unfamiliar pictorial paired associates. Two sets of paired Fourier figures were studied, one approximately 8 weeks before test and the other immediately before test, keeping the correct performance during the tests balanced across the two sets of stimuli. Significant signal increase was observed in the right hippocampus during retrieval of newly studied pairs relative to initially studied pairs. In contrast, significant signal increase was observed in the anterior temporal cortex during retrieval of initially studied pairs relative to newly studied pairs. The greater activity during retrieval of older memory developed in the temporal neocortex provides direct evidence of formation of temporal neocortical representation for stable long-term memory.

Alcohol expectancy priming and drinking behavior: the role of compatibility between prime and expectancy content.

According to information-processing models of alcohol use, alcohol expectancies constitute representations in long-term memory that may be activated in the presence of drinking-related cues, thereby influencing alcohol consumption. A fundamental implication of this approach is that primed expectancies should affect drinking only for those individuals who possess the specific expectancies primed. To test this notion, in the present study, participants were initially assessed on 3 distinct domains of positive alcohol expectancies. Approximately 1 week later, they completed an ad libitum drinking study during which only a single expectancy domain (sociability) was primed in the experimental condition. Consistent with predictions, following exposure to sociability primes but not control primes, individuals with stronger expectancies that alcohol would enhance sociability uniquely showed increased placebo consumption of nonalcoholic beer. These results, which demonstrate the moderating role of compatibility between the specific content of primes and that of underlying expectancies, offer new, direct support for memory network-based models of drinking behavior.

Striatal dopamine D2 binding is related to frontal BOLD response during updating of long-term memory representations

Multi-modal brain imaging was used to examine the relation between individual differences in resting-state striatal dopamine D2 binding and the magnitude of prefrontal BOLD activation during updating of long-term memory (LTM) representations. Increased activity in the left prefrontal cortex was observed when LTM updating was required, and there was a positive correlation between striatal D2 activity and the magnitude of left prefrontal activity during updating. These findings support predictions from neurocomputational models of a relation of dopaminergic neurotransmission to transient cognitive operations and related brain activity.

Category-specificity in visual object recognition

Are all categories of objects recognized in the same manner visually? Evidence from neuropsychology suggests they are not: some brain damaged patients are more impaired in recognizing natural objects than artefacts whereas others show the opposite impairment. Category-effects have also been demonstrated in neurologically intact subjects, but the findings are contradictory and there is no agreement as to why category-effects arise. This article presents a pre-semantic account of category-effects (PACE) in visual object recognition. PACE assumes two processing stages: shape configuration (the binding of shape elements into elaborate shape descriptions) and selection (among competing representations in visual long-term memory), which are held to be differentially affected by the structural similarity between objects. Drawing on evidence from clinical studies, experimental studies with neurologically intact subjects and functional imaging studies, it is argued that PACE can account for category-effects at both behavioural and neural levels in patients and neurologically intact subjects. The theory also accounts for the way in which category-effects are affected by different task parameters (the degree of perceptual differentiation called for), stimulus characteristics (whether stimuli are presented as silhouettes, full line-drawings, or fragmented forms), stimulus presentation (stimulus exposure duration and position) as well as interactions between these parameters.