Visual Perception and Memory Impairments in Children at Risk of Nonverbal Learning Disabilities

Visuospatial working memory (VSWM) and visual perception were examined in two groups aged 11–13, one with children displaying symptoms of nonverbal learning disability (NLD) (n = 18) and the other a control group without learning disabilities (n = 18). The two groups were matched for general verbal abilities, age, gender, and socioeconomic level. The children were presented with VSWM tests involving visual and spatial-simultaneous processes, and also with a classical visual illusion, a classical ambiguous figure, as well as visual perception tests specifically devised for the present study. Results revealed that performance of children at risk of NLD was worse than controls in some VSWM and in visual perception tests without memory involvement; these latter required comparisons of visual stimuli and locations in space with distractors. Moreover, the two groups differed in perceiving the classical ambiguous figure. Findings are discussed in the light of both theoretical and clinical implications.     

How semantic category modulates preschool children’s visual memory

The dynamic interplay between perception and memory has been explored in preschool children by presenting filtered stimuli regarding animals and artifacts. The identification of filtered images was markedly influenced by both prior exposure and the semantic nature of the stimuli. The identification of animals required less physical information than artifacts did. Our results corroborate the notion that the human attention system evolves to reliably develop definite category-specific selection criteria by which living entities are monitored in different ways.     

Charting the Developmental Trajectories of Attention and Executive Function in Chinese School-Aged Children

Attention is a complex domain that has reawakened research interest in recent years. There are relatively few studies that have examined age-related changes across different attention subcomponents, such as selection, maintenance, and control, using large samples covering a wide age range. The present study assessed performance in 466 participants in order to identify the ages at which mature performance was reached across differing attention subcomponents. Furthermore, we investigated whether the nature of the attentional demands or task difficulty predicted the age at which stable levels of performance were reached. The results supported the former rather than the latter alternative.     

An anxiety-induced bias in the perception of a bistable point-light walker

Human sensitivity for social cues is exquisite, as illustrated by the ease with which simplified point-light movements invoke social and emotional responses. Compared to faces, these biological motion stimuli only recently started to be used to explore questions regarding social cognition and anxiety. We presented human point-light walkers that could be perceived as facing towards or facing away from the observer, and tested whether participants with high social anxiety would perceive these bistable stimuli differently, because this type of stimuli has particular relevance for them. The results showed that observers with high social anxiety tended to see walkers as facing away more frequently than those with low social anxiety. This may mean that high socially anxious observers are biased towards the more positive perceptual alternative because they are motivated to protect themselves against threatening social experiences, but we also explore alternative explanations. The findings are in line with the evidence for a positivity bias in perception, also called wishful seeing, but in contrast with the attentional negativity bias often found in social anxiety. We discuss reasons for this divergence and possible limitations of the current study.     

Simultaneous attentional guidance by working-memory and selection history reveals two distinct sources of attention

Recent theories of attention have proposed that selection history is a separate, dissociable source of information that influences attention. The current study sought to investigate the simultaneous involvement of selection history and working-memory on attention during visual search. Experiments 1 and 2 used target feature probability to manipulate selection history and found significant effects of both working-memory and selection history, although working-memory dominated selection history when they cued different locations. Experiment 3 eliminated the contribution of voluntary refreshing of working-memory and replicated the main effects, although selection history became dominant. Using the same methodology, but with reduced probability cue validity, both effects were present in Experiment 4 and did not significantly differ in their contribution to attention. Effects of selection history and working-memory never interacted. These results suggest that selection history and working-memory are separate influences on attention and have little impact on each other. Theoretical implications for models of attention are discussed.     

A laboratory analogue of mirrored-self misidentification delusion: The role of hypnosis,suggestion, and demand characteristics

Mirrored-self misidentification is the delusional belief that one’s own reflection in the mirror is a stranger. In two experiments, we tested the ability of hypnotic suggestion to model this condition. In Experiment 1, we compared two suggestions based on either the delusion’s surface features (seeing a stranger in the mirror) or underlying processes (impaired face processing). Fifty-two high hypnotisable participants received one of these suggestions either with hypnosis or without in a wake control. In Experiment 2, we examined the extent to which social cues and role-playing could account for participants’ behaviour by comparing the responses of 14 hypnotised participants to the suggestion for impaired face processing (reals) with those of 14 nonhypnotised participants instructed to fake their responses (simulators). Overall, results from both experiments confirm that we can use hypnotic suggestion to produce a compelling analogue of mirrored-self misidentification that cannot simply be attributed to social cues or role-playing.     

Attention shifts or volatile representations: What causes binding deficits in visual working memory?

The current study tested two hypotheses of feature binding memory: The attention hypothesis, which suggests that attention is needed to maintain feature bindings in visual working memory (VWM) and the volatile representation hypothesis, which suggests that feature bindings in memory are volatile and easily overwritten, but do not require sustained attention. Experiment 1 tested the attention hypothesis by measuring shifts of overt attention during the study array of a change detection task; serial shifts of attention did not disrupt feature bindings. Experiments 2 and 3 encouraged encoding of more volatile (Experiment 2) or durable (Experiment 3) representations during the study array. Binding change detection performance was impaired in Experiment 2, but not in Experiment 3, suggesting that binding performance is impaired when encoding supports a less durable memory representation. Together, these results suggest that although feature bindings may be volatile and easily overwritten, attention is not required to maintain feature bindings in VWM.     

Book Review

Repetition priming is one of the most robust phenomena in cognitive psychology, but participants vary substantially on the amount of priming that they produce. The current experiments assessed the reliability of repetition priming within individuals. The results suggest that observed differences in the size of the repetition priming effect across participants are largely reliable and result primarily from systematic processes. We conclude that the unreliability of semantic priming observed by Stolz, Besner, and Carr (2005) is specific to uncoordinated processes in semantic memory, and that this unreliability does not generalize to other processes in visual word recognition. We consider the implications of these results for theories of automatic and controlled processes that contribute to priming. Finally, we emphasize the importance of reliability for researchers who use similar paradigms to study individual and group differences in cognition.     

Active suppression of distractors that match the contents of visual working memory

The biased competition theory proposes that items matching the contents of visual working memory will automatically have an advantage in the competition for attention. However, evidence for an automatic effect has been mixed, perhaps because the memory-driven attentional bias can be overcome by top-down suppression. To test this hypothesis, the Pd component of the event-related potential waveform was used as a marker of attentional suppression. While observers maintained a colour in working memory, task-irrelevant probe arrays were presented that contained an item matching the colour being held in memory. We found that the memory-matching probe elicited a Pd component, indicating that it was being actively suppressed. This result suggests that sensory inputs matching the information being held in visual working memory are automatically detected and generate an “attend-to-me” signal, but this signal can be overridden by an active suppression mechanism to prevent the actual capture of attention.     

Limitations of perceptual segmentation on contextual cueing in visual search

In visual search, detection of a target in a repeated layout is faster than search within a novel arrangement, demonstrating that contextual invariances can implicitly guide attention to the target location (“contextual cueing”; Chun & Jiang, 1998). Here, we investigated how display segmentation processes influence contextual cueing. Seven experiments showed that grouping by colour and by size can considerably reduce contextual cueing. However, selectively attending to a relevant subgroup of items (that contains the target) preserved context-based learning effects. Finally, the reduction of contextual cueing by means of grouping affected both the latent learning and the recall of display layouts. In sum, all experiments show an influence of grouping on contextual cueing. This influence is larger for variations of spatial (as compared to surface) features and is consistent with the view that learning of contextual relations critically interferes with processes that segment a display into segregated groups of items.