Resources masquerading as slots: Flexible allocation of visual working memory

Whether the capacity of visual working memory is better characterized by an item-based or a resource-based account continues to be keenly debated. Here, we propose that visual working memory is a flexible resource that is sometimes deployed in a slot-like manner. We develop a computational model that can either encode all items in a memory set, or encode only a subset of those items. A fixed-capacity mnemonic resource is divided among the items in memory. When fewer items are encoded, they are each remembered with higher fidelity, but at the cost of having to rely on an explicit guessing process when probed about an item that is not in memory. We use the new model to test the prediction that participants will more often encode the entire set of items when the demands on memory are predictable.     

A review of existing measures of attentional biases in body image and eating disorders research

Cognitive theories emphasise the important role of attentional biases in the development and maintenance of body image issues and eating pathology. A wealth of research has been conducted to examine attentional biases toward body‐related information among individuals with eating pathology. However, there is considerable variability in the methods that have been used to measure attention and, importantly, these methods tap into different attentional processes. Given the multifaceted nature of attention, it is important for researchers to select the right tools to test their hypotheses. This review critically evaluates the attentional measures that have been used in previous research, primarily the modified Stroop task, dot probe task, visual search task, and eyetracking. The strengths and limitations of each measure will be discussed in order to provide a guide for researchers to further investigate the attentional mechanisms underlying body image issues and eating disorders. Overall, we recommend that researchers use a combination of eyetracking technology and specific reaction‐time measures that target the specific attentional mechanism of interest.     

L’examen psychologique dans le handicap visuel : intérêts et limites méthodologiques

The psychological assessment of visually impaired people (blind or partially sighted) confronts the psychologist with methodological constraints regarding the choice of assessment tools. Both critical judgement and an extensive psychometric knowledge are necessary. The objective of this article is to present the results of a study in which the existing tools in this field are identified. The results of this study bring to light the shortage of tools and methods of investigation specifically designed to assess the different psychological facets (affective, cognitive or conative) of visual impairment. We will then examine the methodological and psychometric issues specifically related to assessment in the field of visual impairment. Although some tools have psychometric qualities for the assessment of blind and visually impaired people (Miller & Skillman, 2003; Reid, 1997), we note that the limits of some tests are often overlooked or ignored (Reid, 1997; Tobin, 1994; Tobin & Hill, 2011). Questions relating to the use, adaptation and translation of foreign language tools are examined. In order to illustrate these points, we present some practices used by psychologists which highlight the limits of currently existing tools for the assessment of the psychological, in particular, the cognitive facet, and in addition provide some recommendations for assessment.     

Action history influences eye movements

Recent research has revealed that simple actions can have a profound effect on subsequent perception – people are faster to find a target that shares features with a previously acted on object even when those features are irrelevant to their task (the action effect). However, the majority of the evidence for this interaction between action and perception has come from manual response data. Therefore, it is unknown whether action affects early visual search processes, if it modulates post-attentional-selection processes, or both. To investigate this, we tracked participants’ spontaneous eye movements as they performed an action effect task. In two experiments we found that participants looked more quickly to the colour of an object they had previously acted on, compared to if they had viewed but not acted on the object, showing that action influenced early visual search processes. Additionally, there was evidence for post-selection effects as well. The results suggest that prior action affects both pre-selection and post-selection processes – spontaneously guiding attention to, and maintaining it on, objects that were previously important to the observer.     

Rummage search by expert dyads,novice dyads and novice individuals for objects hidden in houses

Rummage search is the visual and haptic search of complex environments for targets. In this study, rummage search was explored using a novel analytic framework with expert dyads and novice dyads, as well as novice individuals. Participants sought an unknown number of targets placed in four rooms of a residential house. Some targets were plainly visible whereas others were hidden and could only be found through haptic examination. Expert dyads were very good at the task, conducting a slowed, double-checking exhaustive search, while novices both failed to fixate potential target locations and failed to carry out the appropriate action required to search those locations exhaustively. The novice dyads examined more than the novice individuals, but became more superficial in their search. We conclude that effective rummage searching is a skill enhanced by training.     

Sleep loss and change detection in driving scenes

Driver sleepiness is a significant road safety problem. Sleep-related crashes occur on both urban and rural roads, yet to date driver-sleepiness research has focused on understanding impairment in rural and motorway driving. The ability to detect changes is an attention and awareness skill vital for everyday safe driving. Previous research has demonstrated that person states, such as age or motivation, influence susceptibility to change blindness (i.e., failure or delay in detecting changes). The current work considers whether sleepiness increases the likelihood of change blindness within urban and rural driving contexts. Twenty fully-licenced drivers completed a change detection ‘flicker’ task twice in a counterbalanced design: once following a normal night of sleep (7–8 h) and once following sleep restriction (5 h). Change detection accuracy and response time were recorded while eye movements were continuously tracked. Accuracy was not significantly affected by sleep loss; however, following sleep loss there was some evidence of slowed change detection responses to urban images, but faster responses for rural images. Visual scanning across the images remained consistent between sleep conditions, resulting in no difference in the probability of fixating on the change target. Overall, the results suggest that sleep loss has minimal impact on change detection accuracy and visual scanning for changes in driving scenes. However, a subtle difference in response time to change detection between urban and rural images indicates that change blindness may have implications for sleep-related crashes in more visually complex urban environments. Further research is needed to confirm this finding.     

Visual exploration of pedestrian crossings by adults and children: Comparison of strategies

In pedestrian crossing situations, children are less able to make safe crossing decisions compared to adults.The aim of the present study was to analyze and compare the ocular behaviour of children and adults in the pedestrian crossing situations using the eye tracking. The study involved 22 children ranging in age from 5 years to 6 years 2 months and 22 adults. Children and adults participated in a brief eye tracking session designed to explore field of view in road crossing scenarios. They were presented with four pictures of pedestrian crossing and instructed to observe the pictures as if they were on the sidewalk getting ready to cross the road. The eye movements of the subjects looking at the pictures on the screen were collected through the eye tracker.The results showed that adults used a far more intense exploration of the useful visual field of view. They looked at all the different areas of the field of view more frequently and for a longer time. Another interesting point is that the children gazed at areas and elements that are irrelevant to a safe crossing but prove salient for various reasons. Implications for road safety training are discussed.     

Children's comprehension of visual formal features in television programs

A review of previous studies on children's comprehension of visual formal features did not warrant predictions about children's understanding of the formal features as used in three items from Sesamstraat, the Dutch version of Sesame Street. Therefore, a study was designed in which 45 children in the age range of 4–6 years watched the items and were interviewed. In the first item, a split screen was used to visualize simultaneity of actions. The second item used a subjective camera to suggest the construction of a home video by one of the characters. Version 1 of this item did not show the character while making home video, whereas Version 2 did show the character while filming. The third item contained a dissolve (Version 1) or a cut (Version 2) to indicate the end of a dream. A general conclusion was that although older children (mean AGE=5.9 years) understood the visual formal features better than younger children (mean AGE=4.4 years), the extent to which children in both age groups understood the visual formal features appeared to vary between items and versions. Most children in both age groups understood the split screen in the first item. The younger age group did not understand the subjective camera if the making of the home video was not shown. Both the younger and the older age group understood the version with the cut better than the original version with the dissolve. In the discussion, the question was addressed what the findings of this study and previous studies teach us about children's understanding of visual formal features in general.     

Van Gogh, Chagall and pigeons: picture discrimination in pigeons and humans

The author has previously reported that pigeons can discriminate paintings by different artists. Here, I replicated the previous findings, carried out additional tests and compared discrimination by pigeons with that of humans. In Experiment 1, pigeons were trained to discriminate between paintings by Van Gogh and Chagall. After training, the subjects were tested with different paintings by the same artists. The subjects showed generalization to these paintings. The subjects maintained their discriminative ability for black-and-white paintings and partially occluded paintings. When they were tested with mosaic paintings, the number of correct responses decreased, depending on the level of processing needed. In Experiment 2, human subjects were tested with the same paintings. The subjects showed generalization and decrement of correct responses depending on the degree of mosaic processing. These observations suggest that the visual cognitive function of pigeons is comparable to that of humans. The convergence of higher visual cognition between the two species may stem from similar selection pressures on avian ancestors and our ancestors through their evolution. Accepted after revision: 19 August 2001 Electronic Publication