Short-term Memory Binding Research Articles

Subjective Cognitive Decline.

Subjective Cognitive Decline.

Deficits in visual short-term memory binding in children at risk of non-verbal learning disabilities

It has been hypothesized that learning disabled children meet short-term memory (STM) problems especially when they must bind different types of information, however the hypothesis has not been systematically tested. This study assessed visual STM for shapes and colors and the binding of shapes and colors, comparing a group of children (aged between 8 and 10 years) at risk of non-verbal learning disabilities (NLD) with a control group of children matched for general verbal abilities, age, gender, and socioeconomic level. Results revealed that groups did not differ in retention of either shapes or colors, but children at risk of NLD were poorer than controls in memory for shape-color bindings.

Short term memory for single surface features and bindings in ageing: A replication study

In the present study we replicated a previous experiment investigating visuo-spatial short term memory binding in young and older healthy individuals, in the attempt to verify the pattern of impairment that can be observed in normal elderly for short term memory for single items vs short term memory for bindings. Assessing a larger sample size (25 young and 25 older subjects), using a more appropriate measure of accuracy for a change detection task (A′), and adding the evaluation of speed of performance, we confirmed that old normals show a decline in short term memory for bindings of shape and colour that is of comparable extent, and not major, to the decline in memory for single shapes and single colours. The absence of a specific deficit of short term memory for conjunctions of surface features seems to distinguish cognitive ageing from Alzheimer’s Disease.

Memory binding and white matter integrity in familial Alzheimer's disease.

Binding information in short-term and long-term memory are functions sensitive to Alzheimer's disease. They have been found to be affected in patients who meet criteria for familial Alzheimer's disease due to the mutation E280A of the PSEN1 gene. However, only short-term memory binding has been found to be affected in asymptomatic carriers of this mutation. The neural correlates of this dissociation are poorly understood. The present study used diffusion tensor magnetic resonance imaging to investigate whether the integrity of white matter structures could offer an account. A sample of 19 patients with familial Alzheimer's disease, 18 asymptomatic carriers and 21 non-carrier controls underwent diffusion tensor magnetic resonance imaging, neuropsychological and memory binding assessment. The short-term memory binding task required participants to detect changes across two consecutive screens displaying arrays of shapes, colours, or shape-colour bindings. The long-term memory binding task was a Paired Associates Learning Test. Performance on these tasks were entered into regression models. Relative to controls, patients with familial Alzheimer's disease performed poorly on both memory binding tasks. Asymptomatic carriers differed from controls only in the short-term memory binding task. White matter integrity explained poor memory binding performance only in patients with familial Alzheimer's disease. White matter water diffusion metrics from the frontal lobe accounted for poor performance on both memory binding tasks. Dissociations were found in the genu of corpus callosum which accounted for short-term memory binding impairments and in the hippocampal part of cingulum bundle which accounted for long-term memory binding deficits. The results indicate that white matter structures in the frontal and temporal lobes are vulnerable to the early stages of familial Alzheimer's disease and their damage is associated with impairments in two memory binding functions known to be markers for Alzheimer's disease.

Age differences in short-term memory binding are related to working memory performance across the lifespan.

Memory performance increases during childhood and adolescence, and decreases in old age. Among younger adults, better ability to bind items to the context in which they were experienced is associated with higher working memory performance (Oberauer, 2005). Here, we examined the extent to which age differences in binding contribute to life span age differences in short-term memory (STM). Younger children (N = 85; 10 to 12 years), teenagers (N = 41; 13 to 15 years), younger adults (N = 84; 20 to 25 years), and older adults (N = 86; 70 to 75 years) worked on global and local short-term recognition tasks that are assumed to measure item and item-context memory, respectively. Structural equation models showed that item-context bindings are functioning less well in children and older adults compared with younger adults and teenagers. This result suggests protracted development of the ability to form and recollect detailed short-term memories, and decline of this ability in aging. Across all age groups, better item-context binding was associated with higher working memory performance, indicating that developmental differences in binding mechanisms are closely related to working memory development in childhood and old age.

Relational and conjunctive binding functions dissociate in short-term memory

Remembering complex events requires binding features within unified objects (conjunctions) and holding associations between objects (relations). Recent studies suggest that the two functions dissociate in long-term memory (LTM). Less is known about their functional organization in short-term memory (STM). The present study investigated this issue in patient AE affected by a stroke which caused damage to brain regions known to be relevant for relational functions both in LTM and in STM (i.e., the hippocampus). The assessment involved a battery of standard neuropsychological tasks and STM binding tasks. One STM binding task (Experiment 1) presented common objects and common colors forming either pairs (relations) or integrated objects (conjunctions). Free recall of relations or conjunctions was assessed. A second STM binding task used random polygons and non-primary colors instead (Experiment 2). Memory was assessed by selecting the features that made up the relations or the conjunctions from a set of single polygons and a set of single colors. The neuropsychological assessment revealed impaired delayed memory in AE. AE’s pronounced relational STM binding deficits contrasted with his completely preserved conjunctive binding functions in both Experiments 1 and 2. Only 2.35% and 1.14% of the population were expected to have a discrepancy more extreme than that presented by AE in Experiments 1 and 2, respectively. Processing relations and conjunctions of very elementary nonspatial features in STM led to dissociating performances in AE. These findings may inform current theories of memory decline such as those linked to cognitive aging.

Disruption of verbal-spatial serial memory by extraneous air-traffic speech

The disruptive impact of task-extraneous air-traffic radio speech on a task involving the serial-recall of combined verbal and spatial stimuli (7 letters and their locations) that were broadly analogous to information about aircraft callsigns and movements was examined. Regardless of the dimension to be recalled (identity or spatial location), accuracy was significantly disrupted by the air-traffic speech. Prior knowledge as to which dimension to recall did not affect accuracy and did not interact with the disruptive effect of air-traffic speech, but did extend the time to initiate a response to the first item. The results are discussed with reference to theories of the irrelevant sound effect and stimulus-dimension binding in short-term memory. The vulnerability of cognitive processing related to air-traffic management and similar work environments is also discussed.

Short-term memory binding is impaired in AD but not in non-AD dementias

Binding is a cognitive function responsible for integrating features within complex stimuli (e.g., shape-colour conjunctions) or events within complex memories (e.g., face-name associations). This function operates both in short-term memory (STM) and in long-term memory (LTM) and is severely affected by Alzheimer's disease (AD). However, forming conjunctions in STM is the only binding function which is not affected by healthy ageing or chronic depression. Whether this specificity holds true across other non-AD dementias is as yet unknown. The present study investigated STM conjunctive binding in a sample of AD patients and patients with other non-AD dementias using a task which has proved sensitive to the effects of AD. The STM task assesses the free recall of objects, colours, and the bindings of objects and colours. Patients with AD, frontotemporal dementia, vascular dementia, lewy body dementia and dementia associated with Parkinson's disease showed memory, visuo-spatial, executive and attentional deficits on standard neuropsychological assessment. However, only AD patients showed STM binding deficits. This deficit was observed even when memory for single features was at a similar level across patient groups. Regression and discriminant analyses confirmed that the STM binding task accounted for the largest proportion of variance between AD and non-AD groups and held the greatest classification power to identify patients with AD. STM conjunctive binding places little demands on executive functions and appears to be subserved by components of the memory network which are targeted by AD, but not by non-AD dementias.

Grouping and binding in visual short-term memory.

Findings of 2 experiments are reported that challenge the current understanding of visual short-term memory (VSTM). In both experiments, a single study display, containing 6 colored shapes, was presented briefly and then probed with a single colored shape. At stake is how VSTM retains a record of different objects that share common features: In the 1st experiment, 2 study items sometimes shared a common feature (either a shape or a color). The data revealed a color sharing effect, in which memory was much better for items that shared a common color than for items that did not. The 2nd experiment showed that the size of the color sharing effect depended on whether a single pair of items shared a common color or whether 2 pairs of items were so defined-memory for all items improved when 2 color groups were presented. In explaining performance, an account is advanced in which items compete for a fixed number of slots, but then memory recall for any given stored item is prone to error. A critical assumption is that items that share a common color are stored together in a slot as a chunk. The evidence provides further support for the idea that principles of perceptual organization may determine the manner in which items are stored in VSTM.

Lack of color integration in visual short-term memory binding

Bicolored objects are retained in visual short-term memory (VSTM) less efficiently than unicolored objects. This is unlike shape-color combinations, whose retention in VSTM does not differ from that observed for shapes only. It is debated whether this is due to a lack of color integration and whether this may reflect the function of separate memory mechanisms. Participants judged whether the colors of bicolored objects (each with an external and an internalcolor) were the same or different across two consecutive screens. Colors had to be remembered either individually or in combination. In Experiment 1, external colors in the combined colors condition were remembered better than the internal colors, and performance for both was worse than that in the individual colors condition. The lack of color integration observed in Experiment 1 was further supported by a reduced capacity of VSTM to retain color combinations, relative to individual colors (Experiment 2). An additional account was found in Experiment 3, which showed spared color-color binding in the presence of impaired shape-color binding in a brain-damaged patient, thus suggesting that these two memory mechanisms are different.

How emotional pictures influence visuospatial binding in short-term memory in ageing and Alzheimer’s disease?

The present study examines the prediction that emotion can facilitate short-term memory. Nevertheless, emotion also recruits attention to process information, thereby disrupting short-term memory when tasks involve high attentional resources. In this way, we aimed to determine whether there is a differential influence of emotional information on short-term memory in ageing and Alzheimer’s disease (AD). Fourteen patients with mild AD, 14 healthy older participants (NC), and 14 younger adults (YA) performed two tasks. In the first task, involving visual short-term memory, participants were asked to remember a picture among four different pictures (negative or neutral) following a brief delay. The second task, a binding memory task, required the recognition by participants of a picture according to its spatial location. The attentional cost involved was higher than for the first task. The pattern of results showed that visual memory performance was better for negative stimuli than for neutral ones, irrespective of the group. In contrast, binding memory performance was essentially poorer for the location of negative pictures in the NC group, and for the location of both negative and neutral stimuli in the AD group, in comparison to the YA group. Taken together, these results show that emotion has beneficial effects on visual short-term memory in ageing and AD. In contrast, emotion does not improve their performances in the binding condition.

Specific deficit of colour–colour short-term memory binding in sporadic and familial Alzheimer's disease

Short-term memory binding of visual features which are processed across different dimensions (shape–colour) is impaired in sporadic Alzheimer's disease, familial Alzheimer's disease, and in asymptomatic carriers of familial Alzheimer's disease. This study investigated whether Alzheimer's disease also impacts on within-dimension binding processes. The study specifically explored whether visual short-term memory binding of features of the same type (colour–colour) is sensitive to Alzheimer's disease. We used a neuropsychological battery and a short-term memory binding task to assess patients with sporadic Alzheimer's disease (Experiment 1), familial Alzheimer's disease (Experiment 2) due to the mutation E280A of the Presenilin-1 gene and asymptomatic carriers of the mutation. The binding task assessed change detection within arrays of unicoloured objects (Colour Only) or bicoloured objects the colours of which had to be remembered separately (Unbound Colours) or together (Bound Colours). Performance on the Bound Colours condition (1) explained the largest proportion of variance between patients (sporadic and familial Alzheimer's disease), (2) combined more sensitivity and specificity for the disease than other more traditional neuropsychological tasks, (3) identified asymptomatic carriers of the mutation even when traditional neuropsychological measures and other measures of short-term memory did not and, (4) contrary to shape–colour binding, correlated with measures of hippocampal functions. Colour–colour binding and shape–colour binding both appear to be sensitive to AD even though they seem to rely on different brain mechanisms.

Strong and long: Effects of word length on phonological binding in verbal short-term memory

This study examined the effects of item length on the contribution of linguistic knowledge to immediate serial recall (ISR). Long words are typically recalled more poorly than short words, reflecting the greater demands that they place on phonological encoding, rehearsal, and production. However, reverse word length effects--that is, better recall of long than short words--can also occur in situations in which phonological maintenance is difficult, suggesting that long words derive greater support from long-term lexical knowledge. In this study, long and short words and nonwords (containing one vs. three syllables) were presented for immediate serial recall in (a) pure lists and (b) unpredictable mixed lists of words and nonwords. The mixed-list paradigm is known to disrupt the phonological stability of words, encouraging their phonemes to recombine with the elements of other list items. In this situation, standard length effects were seen for nonwords, while length effects for words were absent or reversed. A detailed error analysis revealed that long words were more robust to the mixed-list manipulation than short words: Their phonemes were less likely to be omitted and to recombine with phonemes from other list items. These findings support an interactive view of short-term memory, in which long words derive greater benefits from lexical knowledge than short words-especially when their phonological integrity is challenged by the inclusion of nonwords in mixed lists.

Object — Position Binding in Visual Short-Term Memory for Sequentially Presented Unfamiliar Stimuli

The effect of spatial position on visual short-term memory (VSTM) for sequentially presented objects has been investigated relatively little, despite the fact that vision in natural environments is characterised by frequent changes in object position and gaze location. We investigated the effect of reusing previously examined spatial positions on VSTM for object appearance. Observers performed a yes-no recognition task following a memory display comprising briefly presented 1/f noise discs (ie possessing spectral properties akin to natural images) shown sequentially at random coordinates. At test, single stimuli were presented either at original spatial positions, new positions, or at a fixed central position. Results, interpreted in terms of appearance and position preview effects, indicate that, where original spatial positions were reused at test, memory performance was elevated by more than 25%, despite that spatial position was task-irrelevant (in the sense that it could not be used to facilitate a correct response per se). This study generalises object-spatial-position binding theory to a sequential display scenario in which the influences of extrafoveal processing, spatial context cues, and long-term memory support were minimised, thereby eliminating the hypothesis that object priming is the principal cause of the 'same-position advantage' in VSTM.

Feature binding in visual short-term memory is unaffected by task-irrelevant changes of location, shape, and color

Three experiments used a change detection paradigm across a range of study-test intervals to address the respective contributions of location, shape, and color to the formation of bindings of features in sensory memory and visual short-term memory (VSTM). In Experiment 1, location was designated task irrelevant and was randomized between study and test displays. The task was to detect changes in the bindings between shape and color. In Experiments 2 and 3, shape and color, respectively, were task irrelevant and randomized, with bindings tested between location and color (Experiment 2) and location and shape (Experiment 3). At shorter study-test intervals, randomizing location was most disruptive, followed by shape and then color. At longer intervals, randomizing any task-irrelevant feature had no impact on change detection for bindings between features, and location had no special role. Results suggest that location is crucial for initial perceptual binding but loses that special status once representations are formed in VSTM, which operates according to different principles, than do visual attention and perception.

Visual short-term memory binding deficits in familial Alzheimer’s disease

Short-term memory binding is a memory function that underpins the temporary retention of complex objects (e.g. shapes with colours). In the verbal domain, this function has been found to be impaired in sporadic Alzheimer's disease. Whether short-term memory binding is also impaired in familial Alzheimer's disease, whether this impairment extends to the visual domain and whether it could be detected earlier than other cognitive deficits are issues yet to be investigated. Twenty two patients with familial Alzheimer's disease caused by the E280A single presenilin-1 mutation, thirty carriers of the mutation who did not meet Alzheimer's disease criteria (asymptomatic carriers) and 30 healthy relatives (non-carrier healthy controls) were assessed with a visual short-term memory task and a neuropsychological battery. The short-term memory task assessed the recognition of shapes, colours or shape-colour bindings presented in two consecutive arrays (i.e. study and test). Changes, which always occurred in the test array, consisted of new features replacing studied features (single feature conditions) or of features swapping across items (the binding condition). The neuropsychological battery comprised tests of associative and non-associative memory, attention, language, visuospatial and executive functions. Patients with Alzheimer's disease and asymptomatic carriers performed significantly worse than healthy controls in the feature binding condition only. Group comparisons between asymptomatic carriers and healthy controls on standard neuropsychological tasks revealed no significant differences. Classification and area under the curve analyses confirmed that the binding task combines more sensitivity and specificity for patients with Alzheimer's disease and most notably for asymptomatic carriers of the mutation than other traditional neuropsychological measures. This suggests that visual short-term memory binding deficits may be a preclinical marker for familial Alzheimer's disease.

Visual short-term memory binding in Alzheimer’s disease and depression

The differential diagnosis between Alzheimer's disease (AD) and major depression (MD) in the elderly can be problematic because the cognitive profile of the two conditions overlaps. Associative learning tasks seem to separate AD from MD. However, they are sensitive to the effects of normal ageing. Short-term memory-binding tasks have proved insensitive to the effects of normal ageing and highly sensitive to AD. However, they have not been used to differentiate AD from MD. The present study was aimed at investigating visual short-term memory binding in AD and MD. Fourteen AD patients, 14 patients with MD, and 14 healthy older adults were asked to perform a visual short-term memory binding task that investigated the retention of shapes, colors, or combinations of shapes and colors. Participants were to recognize changes occurring between two consecutive displays either in a single dimension (i.e., shape or color only) or in two dimensions (i.e., shape-color binding). Short-term memory performance for shape or color only was equivalent across groups. The only significant effect found was in short-term memory for shape-color binding and this was due to AD patients performing poorly in this condition only. The results extend previous findings in AD to visual short-term memory and suggest that the specific impairment in binding information in memory differentiates between the performance of AD and patients with MD.

Selective impairment in visual short-term memory binding

Dissociations within binding in perception have been reported after brain damage. In short-term memory (STM), feature binding and feature processing appear to rely on separate processes. However, dissociations within binding in STM following brain damage have not been reported to date. We report on the case E.S. who, after removal of a left medial sphenoid ridge meningioma, developed a selective impairment of visual STM (VSTM) binding. We found that, despite having normal perceptual binding, E.S. was unable to retain in VSTM features bound into objects while she could retain individual features as well as controls did (Experiments 1–2, 4, and 6). Her verbal STM for bound and single features remains intact (Experiments 3 and 5). E.S.'s performance suggests that STM binding can be dissociated from STM for single features across visual and verbal domains. The results are discussed in the light of current models of STM.

Binding feature dimensions in visual short-term memory

We explored several possible influences on binding in visual short-term memory (VSTM) performance. The task was to report whether a test object was the same (“old” trials) or different (“new” trials) from any of the sample objects seen a second ago. The objects were composed of two features that varied from continuous to discrete shapes and colors. In “old” trials the test object appeared either in the same or different position. In “new” trials the test object differed along both features, requiring storage of only one feature per object; along one feature, requiring no binding but storage of all features; or it was created by recombining features from the sample, which requires binding. Existing storage hypotheses are unable to explain the similar sensitivity ( d′) obtained in the two last conditions when position remained the same and may suggest that links are created between positions and features. Highest sensitivity occurred when the test object remained at the same position, required no binding, and discrete features were used. Object-type × position, and feature combination × position interactions occurred, suggesting different storage modes depending on whether objects change position during retention.

Semantic memory is key to binding phonology: Converging evidence from immediate serial recall in semantic dementia and healthy participants

Patients with semantic dementia (SD) make numerous phoneme migration errors when recalling lists of words they no longer fully understand, suggesting that word meaning makes a critical contribution to phoneme binding in verbal short-term memory. Healthy individuals make errors that appear similar when recalling lists of nonwords, which also lack semantic support. Although previous studies have assumed that the errors in these two groups stem from the same underlying cause, they have never been directly compared. We tackled this issue by examining immediate serial recall for SD patients and controls on “pure” word lists and “mixed” lists that contained a mixture of words and nonwords. SD patients were equally poor at pure and mixed lists and made numerous phoneme migration errors in both conditions. In contrast, controls recalled pure lists better than mixed lists and only produced phoneme migrations for mixed lists. We also examined the claim that semantic activation is critical for words in the primacy portion of the list. In fact, the effect of mixed lists was greatest for later serial positions in the control group and in the SD group recall was poorest towards the ends of lists. These results suggest that mixing nonwords with words in healthy participants closely mimics the impact of semantic degradation in SD on word list recall. The study provides converging evidence for the idea that lexical/semantic knowledge is an important source of constraint on phonological coherence, ensuring that phonemes in familiar words are bound to each other and emerge together in recall.