The impact of stimulus configuration on visual short-term memory decline in normal aging and mild cognitive impairment.

INTRODUCTION: When we memorize simultaneous items, we not only store information about specific items and/or their locations but also how items are related to each other. Such relational information can be parsed into spatial (spatial configuration) and identity (object configuration) components. Both these configurations are found to support performance during a visual short-term memory (VSTM) task in young adults. How the VSTM performance of older adults is influenced by object/spatial configuration is less understood, which this study investigated. METHODS: Twenty-nine young adults, 29 normally aging older adults, and 20 older adults with mild cognitive impairment (MCI) completed two yes-no memory-recognition experiments for four simultaneously presented items (2.5 s). Test display items were presented either at the same locations as the memory items (Experiment 1) or were globally shifted (Experiment 2). One of the test display items (target) was highlighted with a square box; participants indicated whether this item was shown in the preceding memory display. Both experiments comprised four conditions where nontarget items changed as follows: (i) nontarget items remained the same; (ii) nontarget items were replaced by new items; (iii) nontarget items switched locations; (iv) nontarget items were replaced by square boxes. RESULTS: Performance (% correct) in both older groups was significantly reduced than young adults in both experiments and each condition. For the MCI adults, significantly reduced performance (vs. normal older adults) was found only for Experiment 1. CONCLUSION: VSTM for simultaneous items declines significantly in normal aging; the decline is not influenced differently by spatial/object configuration change. The ability of VSTM to differentiate MCI from normal cognitive aging is apparent only where the spatial configuration of stimuli is retained at original locations. Findings are discussed in terms of the reduced ability to inhibit irrelevant items and location priming (by repetition) deficits.

Self-isolation negatively impacts self-management of diabetes during the coronavirus (COVID-19) pandemic.

BACKGROUND/AIM: People with diabetes are at a greater risk of serious complications from Coronavirus disease (COVID-19). Self-management of diabetes is therefore of paramount importance. The purpose of this study is to compare self-management of diabetes pre-COVID-19 and during the COVID-19 pandemic. METHODS: 679 participants with diabetes completed an online structured questionnaire survey. Various exposure variables (demographics, duration, treatment and complications of diabetes, self-isolation, etc.) were analysed to examine associations with the following outcome variables: (i) fluctuation of blood glucose levels, (ii) access to diabetes medicine, (iii) access to healthy diet, (iv) physical activity. Adjusted multiple regression analysis ascertained significant associations for each outcome variable against exposure variables. RESULTS: Multiple regression analysis showed that self-isolation was significantly associated with greater fluctuation in blood glucose levels (OR = 1.8, 95% CI = 1.2-2.6, p = 0.005), reduced access to diabetes medicine (OR = 1.9, 95% CI = 1.1-3.1, p = 0.02) and reduced access to healthy diet (OR = 3.0, 95% CI = 2.0-4.6, p < 0.001). Fluctuation in blood glucose level was also significantly associated with having at least one complication of diabetes (OR = 2.2, 95% CI = 1.2-3.9, p = 0.008) and reduced access to diabetes medicine was significantly higher in people who were on insulin (OR = 2.1, 95% CI = 1.3-3.3, p = 0.001). CONCLUSIONS: Self-isolation was shown to impact almost all factors that influence self-management of diabetes. A targeted approach to improved access to diabetes medicine, healthy diet for people who needed to self-isolate is vital in order to ensure that they are able to self-manage their diabetes effectively.

How does aging influence object-location and name-location binding during a visual short-term memory task?

Objective: Age-related impairments in human visual short-term memory (VSTM) may reflect a reduced ability to retain bound object representations, viz., object form, name, spatial, and temporal location (so called 'memory sources'). Our objective is to examine how healthy aging affects VSTM in a battery of memory recognition tasks in which sequentially presented objects, locations, and names (as auditory stimuli) were learned, with one component cued at test.Methods: Thirty-six young healthy adults (18-30 years) and 36 normally aging older adults (>60 years with no underlying health and vision issues) completed five VSTM tasks: 1. Object recognition for two or four objects; 2. Spatial location recognition for two or four objects; 3. Bound object-location recognition for two or four objects; 4. Object recognition with location priming for two or four objects; 5. Bound name (auditory)-location (cross-modal) recognition for four objects.Results: Significantly lower performance for older adults was found in spatial location recognition [task 2, p = 0.03], bound object-location recognition [task 3, p = 0.001], object recognition with location priming [task 4, p = 0.02], and bound name-location recognition [task 5, p = 0.001, independent samples t-test] tasks. A significant age group-task interaction was found (p = 0.02).Conclusion: Performance for all tests except test 1 was impaired in older adults. Lower performance for older adults was most significant in VSTM tasks requiring object-location (visual only) or name-location (auditory and visual) binding. The findings are compatible with the 'memory source' model, demonstrating that age-related binding performance is influenced by spatial coding and location priming deficits.

Need to improve awareness and treatment compliance in high-risk patients for diabetic complications in Nepal.

OBJECTIVE/INTRODUCTION: It is known that knowledge, awareness, and practice influence diabetic control. We compared factors pertaining to healthy lifestyle (exercising, avoiding smoking), self-help (attending appointments, following treatment regimens), and diabetic awareness in high-risk patients for diabetic complications, specifically, those on insulin versus non-insulin treatment, and also those with a longer diabetic duration (≥5 years) versus a shorter duration. METHODS: 200 consecutive patients with type 2 diabetes (52.0±11.6 years) attending diabetic clinic at a referral hospital in Nepal were recruited. A structured questionnaire explored non-clinical parameters including age, gender, diabetic duration, awareness about diabetes control, self-help, and lifestyle. Clinical data were also measured: HbA1c, fasting blood sugar (FBS), blood pressure, and treatment type (insulin, diet/tablet). RESULTS: A significantly higher proportion of patients on insulin (vs non-insulin) or with diabetic duration ≥5 years (vs <5 years) self-reported not doing regular exercise, forgetting to take medicine, and not knowing whether their diabetes was controlled (p≤0.005). HbA1c/FBS levels were significantly higher for patients on insulin or with a longer diabetic duration (p≤0.001). 92% of those on insulin (vs 31% on non-insulin) and 91% with diabetic duration ≥5 years (vs 28% of <5 years) self-reported to seeking medical help due to episodes of uncontrolled blood sugar in the last year (p<0.001). CONCLUSION: Poor self-help/lifestyle and reduced knowledge/awareness about diabetic control was found in patients on insulin or with longer diabetic duration. This is a worrying finding as these patients are already at high risk for developing diabetic complications. The findings highlight need for targeting this more vulnerable group and provide more support/diabetic educational tools.

Patients with Mild Cognitive Impairment Show Lower Visual Short-Term Memory Performance in Feature Binding Tasks.

BACKGROUND: Early cognitive changes in people at risk of developing dementia may be detected using behavioral tests that examine the performance of typically affected brain areas, such as the hippocampi. An important cognitive function supported by the hippocampi is memory binding, in which object features are associated to create a unified percept. AIM: To compare visual short-term memory (VSTM) binding performance for object names, locations, and identities between a participant group known to be at higher risk of developing dementia (mild cognitive impairment [MCI]) and healthily aging controls. METHODS: Ten MCI and 10 control participants completed five VSTM tests that differed in their requirement of remembering bound or unbound object names, locations, and identities, along with a standard neuropsychological test (Addenbrooke's Cognitive Examination [ACE]-III). RESULTS: The performance of the MCI participants was selectively and significantly lower than that of the healthily aging controls for memory tasks that required object-location or name-location binding. CONCLUSION: Tasks that measure unimodal (object-location) and crossmodal (name-location) binding performance appear to be particularly effective for the detection of early cognitive changes in those at higher risk of developing dementia due to Alzheimer's disease.

Spatiotemporal proximity effects in visual short-term memory examined by target-nontarget analysis.

Visual short-term memory (VSTM) is a limited-capacity system that holds a small number of objects online simultaneously, implying that competition for limited storage resources occurs (Phillips, 1974). How the spatial and temporal proximity of stimuli affects this competition is unclear. In this 2-experiment study, we examined the effect of the spatial and temporal separation of real-world memory targets and erroneously selected nontarget items examined during location-recognition and object-recall tasks. In Experiment 1 (the location-recognition task), our test display comprised either the picture or name of 1 previously examined memory stimulus (rendered above as the stimulus-display area), together with numbered square boxes at each of the memory-stimulus locations used in that trial. Participants were asked to report the number inside the square box corresponding to the location at which the cued object was originally presented. In Experiment 2 (the object-recall task), the test display comprised a single empty square box presented at 1 memory-stimulus location. Participants were asked to report the name of the object presented at that location. In both experiments, nontarget objects that were spatially and temporally proximal to the memory target were confused more often than nontarget objects that were spatially and temporally distant (i.e., a spatiotemporal proximity effect); this effect generalized across memory tasks, and the object feature (picture or name) that cued the test-display memory target. Our findings are discussed in terms of spatial and temporal confusion "fields" in VSTM, wherein objects occupy diffuse loci in a spatiotemporal coordinate system, wherein neighboring locations are more susceptible to confusion. (PsycINFO Database Record

Change Detection in Visual Short-Term Memory: The Relative Impact of Pairwise Switches and Identity Substitutions.

Numerous kinds of visual event challenge our ability to keep track of the objects that populate our visual environment from moment to moment. These include blinks, occlusion, shifting visual attention, and changes to object's visual and spatial properties over time. These visual events may lead to objects falling out of our visual awareness, but can also lead to unnoticed changes, such as undetected object replacements and positional exchanges. Current visual memory models do not predict which visual changes are likely to be the most difficult to detect. We examine the accuracy with which switches (where two objects exchange locations) and substitutions (where one or two objects are replaced) are detected. Inferior performance for one-object substitutions versus two-objects switches, along with superior performance for two-object substitutions versus two-object switches was found. Our results are interpreted in terms of object file theory, trade-offs between diffused and localized attention, and net visual change.

How does aging affect the types of error made in a visual short-term memory 'object-recall' task?

This study examines how normal aging affects the occurrence of different types of incorrect responses in a visual short-term memory (VSTM) object-recall task. Seventeen young (Mean = 23.3 years, SD = 3.76), and 17 normally aging older (Mean = 66.5 years, SD = 6.30) adults participated. Memory stimuli comprised two or four real world objects (the memory load) presented sequentially, each for 650 ms, at random locations on a computer screen. After a 1000 ms retention interval, a test display was presented, comprising an empty box at one of the previously presented two or four memory stimulus locations. Participants were asked to report the name of the object presented at the cued location. Errors rates wherein participants reported the names of objects that had been presented in the memory display but not at the cued location (non-target errors) vs. objects that had not been presented at all in the memory display (non-memory errors) were compared. Significant effects of aging, memory load and target recency on error type and absolute error rates were found. Non-target error rate was higher than non-memory error rate in both age groups, indicating that VSTM may have been more often than not populated with partial traces of previously presented items. At high memory load, non-memory error rate was higher in young participants (compared to older participants) when the memory target had been presented at the earliest temporal position. However, non-target error rates exhibited a reversed trend, i.e., greater error rates were found in older participants when the memory target had been presented at the two most recent temporal positions. Data are interpreted in terms of proactive interference (earlier examined non-target items interfering with more recent items), false memories (non-memory items which have a categorical relationship to presented items, interfering with memory targets), slot and flexible resource models, and spatial coding deficits.

Manual tapping enhances visual short-term memory performance where visual and motor coordinates correspond.

Visuo-manual interaction in visual short-term memory (VSTM) has been investigated little, despite its importance in everyday tasks requiring the coordination of visual perception and manual action. This study examines the influence of a manual action performed during stimulus learning on a subsequent VSTM test for object appearance. The memory display comprised a sequence of briefly presented 1/f noise discs (i.e., possessing spectral properties akin to natural images), wherein each new stimulus was presented at a unique screen location. Participants either did (or did not) perform a concurrent manual action (spatial tapping) task requiring that a hand-held stylus be moved to a position on a touch tablet that corresponded (or did not correspond) to the screen position of each new stimulus as it appeared. At test, a single stimulus was presented, either at one of the original screen positions, or at a new position. Two factors were examined: the execution (or otherwise) of spatial tapping at a corresponding or non-corresponding position, and the presentation of test stimuli either at their original spatial positions, or at new positions. We find that spatial tapping at corresponding positions elevates VSTM performance by more than 15%, but this occurs only when stimulus positions are matched from memory to test display. Our findings suggest that multimodal attentional focus during stimulus encoding (incorporating visual, spatial, and manual components) leads to stronger, more robust memory representations. We posit several possible explanations for this effect.

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.