José M. Reales

Implicit and Explicit Memory for Visual and Haptic Objects: Cross-Modal Priming Depends on Structural Descriptions

Previous research on cross-modal priming has used verbal stimuli presented to vision and audition. This study examined whether priming is modality specific and whether there are dissociations between several implicit and explicit memory measures when familiar objects are presented to vision and touch. The experiments showed significant priming between and within modalities. Experiment 1 showed similar presemantic priming between and within modalities. Experiment 2 found robust cross-modal priming using 2 different implicit memory tests: picture-fragment completion and object decision. However, priming was greater when pictures were presented at study and test than when visual or haptic objects were given at study and pictures were shown at test. Conversely, the study of objects haptically or visually enhanced free recall. Experiment 3 found that within- and cross-modal priming were both unaffected by study-test delay. The findings suggest that similar structural descriptions mediate object priming in vision and touch. The goal of this study was to explore whether the perceptual representations of visual and haptic real objects that mediate priming are modality specific and how this represented information is accessed under implicit and explicit conditions. Graf and Schacter (1985) used the terms implicit and explicit to refer to two different ways of accessing prior acquired information, as well as the forms in which memory is expressed. Explicit memory for objects is related to conscious recollection of previous experience with the objects. In contrast, implicit memory is unveiled when previous experiences with the objects do not require conscious or intentional recollection of previously perceived information (Schacter, 1987). Implicit memory is usually assessed by showing repetition priming effects, which mean better performance in accuracy or response time for stimuli that have been

Intact haptic priming in normal aging and Alzheimer's disease: evidence for dissociable memory systems

This study is the first to report complete priming in Alzheimers disease (AD) patients and older control subjects for objects presented haptically. To investigate possible dissociations between implicit and explicit objects representations, young adults, Alzheimers patients, and older controls performed a speeded object naming task followed by a recognition task. Similar haptic priming was exhibited by the three groups, although young adults responded faster than the two older groups. Furthermore, there was no difference in performance between the two healthy groups. On the other hand, younger and older healthy adults did not differ on explicit recognition while, as expected, AD patients were highly impaired. The double dissociation suggests that different memory systems mediate both types of memory tasks. The preservation of intact haptic priming in AD provides strong support to the idea that object implicit memory is mediated by a memory system that is different from the medial-temporal diencephalic system underlying explicit memory, which is impaired early in AD. Recent imaging and behavioral studies suggest that the implicit memory system may depend on extrastriate areas of the occipital cortex although somatosensory cortical mechanisms may also be involved.

Video game training enhances cognition of older adults: A meta-analytic study.

It has been suggested that video game training enhances cognitive functions in young and older adults. However, effects across studies are mixed. We conducted a meta-analysis to examine the hypothesis that training healthy older adults with video games enhances their cognitive functioning. The studies included in the meta-analysis were video game training interventions with pre- and posttraining measures. Twenty experimental studies published between 1986 and 2013, involving 474 trained and 439 healthy older controls, met the inclusion criteria. The results indicate that video game training produces positive effects on several cognitive functions, including reaction time (RT), attention, memory, and global cognition. The heterogeneity test did not show a significant heterogeneity (I(2) = 20.69%) but this did not preclude a further examination of moderator variables. The magnitude of this effect was moderated by methodological and personal factors, including the age of the trainees and the duration of the intervention. The findings suggest that cognitive and neural plasticity is maintained to a certain extent in old age. Training older adults with video games enhances several aspects of cognition and might be a valuable intervention for cognitive enhancement.

Symmetry in haptic and in visual shape perception

Four experiments tested the hypothesis that bilateral symmetry is an incidental encoding property in vision, but can also be elicited as an incidental effect in touch, provided that sufficient spatial reference information is available initially for haptic inputs to be organized spatially. Experiment 1 showed that symmetry facilitated processing in vision, even though the task required judgments of stimulus closure rather than the detection of symmetry. The same task and stimuli failed to show symmetry effects in tactual scanning by one finger (Experiment 2). Experiment 3 found facilitating effects for vertically symmetric open stimuli, although not for closed patterns, in two-forefinger exploration when the fore-fingers had previously been aligned to the body midaxis to provide body-centered spatial reference. The one-finger exploration condition again failed to show symmetry effects. Experiment 4 replicated the facilitating effects of symmetry for open symmetric shapes in tactual exploration by the two (previously aligned) forefingers. Closed shapes again showed no effect. Spatial-reference information, finger movements, and stimulus factors in shape perception by touch are discussed.

Selective attention modulates visual and haptic repetition priming: effects in aging and Alzheimer's disease

In two experiments, we examined the effect of selective attention at encoding on repetition priming in normal aging and Alzheimers disease (AD) patients for objects presented visually (experiment 1) or haptically (experiment 2). We used a repetition priming paradigm combined with a selective attention procedure at encoding. Reliable priming was found for both young adults and healthy older participants for visually presented pictures (experiment 1) as well as for haptically presented objects (experiment 2). However, this was only found for attended and not for unattended stimuli. The results suggest that independently of the perceptual modality, repetition priming requires attention at encoding and that perceptual facilitation is maintained in normal aging. However, AD patients did not show priming for attended stimuli, or for unattended visual or haptic objects. These findings suggest an early deficit of selective attention in AD. Results are discussed from a cognitive neuroscience approach.

Brain training with non-action video games enhances aspects of cognition in older adults: a randomized controlled trial

Age-related cognitive and brain declines can result in functional deterioration in many cognitive domains, dependency, and dementia. A major goal of aging research is to investigate methods that help to maintain brain health, cognition, independent living and wellbeing in older adults. This randomized controlled study investigated the effects of 20 1-h non-action video game training sessions with games selected from a commercially available package (Lumosity) on a series of age-declined cognitive functions and subjective wellbeing. Two groups of healthy older adults participated in the study, the experimental group who received the training and the control group who attended three meetings with the research team along the study. Groups were similar at baseline on demographics, vocabulary, global cognition, and depression status. All participants were assessed individually before and after the intervention, or a similar period of time, using neuropsychological tests and laboratory tasks to investigate possible transfer effects. The results showed significant improvements in the trained group, and no variation in the control group, in processing speed (choice reaction time), attention (reduction of distraction and increase of alertness), immediate and delayed visual recognition memory, as well as a trend to improve in Affection and Assertivity, two dimensions of the Wellbeing Scale. Visuospatial working memory (WM) and executive control (shifting strategy) did not improve. Overall, the current results support the idea that training healthy older adults with non-action video games will enhance some cognitive abilities but not others.

Haptic discrimination of bilateral symmetry in 2-dimensional and 3-dimensional unfamiliar displays

In five experiments, we tested the accuracy and sensitivity of the haptic system in detecting bilateral symmetry of raised-line shapes (Experiments 1 and 2) and unfamiliar 3-D objects (Experiments 3–5) under different time constraints and different modes of exploration. Touch was moderately accurate for detecting this property in raised displays. Experiment 1 showed that asymmetric judgments were systematically more accurate than were symmetric judgments with scanning by one finger. Experiment 2 confirmed the results of Experiment 1 but also showed that bimanual exploration facilitated processing of symmetric shapes without improving asymmetric detections. Bimanual exploration of 3-D objects was very accurate and significantly facilitated processing of symmetric objects under different time constraints (Experiment 3). Unimanual exploration did not differ from bimanual exploration (Experiment 4), but restricting hand movements to one enclosure reduced performance significantly (Experiment 5). Spatial reference information, signal detection measures, and hand movements in processing bilateral symmetry by touch are discussed.

Visual and haptic discrimination of symmetry in unfamiliar displays extended in the z-axis

We investigated, in two experiments, the discrimination of bilateral symmetry in vision and touch using four sets of unfamiliar displays. They varied in complexity from 3 to 30 turns. Two sets were 2-D flat forms (raised-line shapes and raised surfaces) while the other two were 3-D objects constructed by extending the 2-D shapes in height (short and tall objects). Experiment 1 showed that visual accuracy was excellent but latencies increased for raised-line shapes compared with 3-D objects. Experiment 2 showed that unimanual exploration was more accurate for asymmetric than for symmetric judgments, but only for 2-D shapes and short objects. Bimanual exploration at the body midline facilitated the discrimination of symmetric shapes without changing performance with asymmetric ones. Accuracy for haptically explored symmetric stimuli improved as the stimuli were extended in the third dimension, while no such a trend appeared for asymmetric stimuli. Unlike vision, haptic response latency decreased for 2-D shapes compared with 3-D objects. The present results are relevant to the understanding of symmetry discrimination in vision and touch.

Cognitive function in normal aging and in older adults with mild cognitive impairment

BACKGROUND In this study, we investigated the effects of normal and pathological (mild cognitive impairment, MCI) aging on several cognitive functions (processing speed, executive control and implicit memory). METHOD Twenty young adults, 20 healthy older adults and 20 elders with MCI performed a series of cognitive tasks under controlled conditions. These tasks were simple and choice reaction time, the Wisconsin Card Sorting Test (WCST), and an implicit memory task for attended and unattended objects at encoding. RESULTS The MCI group showed pronounced declines in processing speed and executive control tasks. Interestingly, young and healthy older participants showed repetition priming for stimuli that were attended at encoding, but the MCI group did not. CONCLUSIONS In this latter group, the lack of repetition priming for attended objects in the implicit memory task resembled that of Alzheimer disease (AD) patients and suggests an early deficit of selective attention that might be a marker of pathological aging.

Ageing affects event-related potentials and brain oscillations: a behavioral and electrophysiological study using a haptic recognition memory task.

In this electrophysiological study, we investigated the effects of ageing on recognition memory for three-dimensional (3D) familiar objects presented to touch in a continuous paradigm. To examine changes in event-related potentials (ERPs) and brain oscillations, we recorded the EEGs of healthy groups of young (n=14; mean age=32.3 years) and older adults (n=14; mean age=65.1). Both age groups exhibited similar accuracy and exploration times when making old-new judgments. Young and older participants showed a marginally significant ERP old/new effect widely distributed over the scalp between 550-750 ms. In addition, the elders showed lower amplitude than younger participants within 1200-1500 ms. There were age-related differences in brain oscillations as measured by event-related spectral perturbation (ERSP). Older adults showed greater alpha and beta power reductions than young participants, suggesting the recruitment of additional neural resources. In contrast, the two age groups showed a reliable old/new effect in the theta band that temporarily overlapped the ERP old/new effect. The present results suggest that despite similar behavioral performance, the young and older adults recruited different neural resources to perform a haptic recognition task.