Binding time: Investigations on the integration of visual stimulus duration.

The perception of and reaction to objects creates bindings of (object) features and responses, also called event files. In this context, time is a so far understudied feature. We conducted four experiments to investigate whether the duration of visual stimuli is also integrated into such event files. Experiments 1, 2, and 4 used a simple colour classification task and in Experiment 3 the location of a stimulus had to be classified. In all Experiments, the presentation duration of the stimuli (coloured circles) was either short (20 ms) or long (300 ms). We expected partial repetition costs as an indicator of binding. That is, performance should be better when both colour (Experiment 3: location) and duration repeat or alternate relative to partial repetitions. Results showed no partial repetition costs in Experiments 1 and 3, indicating no integration of duration into visual event files. Experiments 2 and 4 revealed partial repetition costs. Performance was better when Colour and Duration repeated compared with a partial repetition. What distinguishes the latter two experiments from the former is that the coloured stimuli could change their presentation location. The results of all four experiments show a pattern that duration can be integrated into visual event files depending on two criteria: The experimental context holds the possibility of a location change of the target stimulus (Experiments 2 and 4) and the location itself is not response relevant (Experiment 3). The role of location changes for the integration of temporal stimulus features into visual event files is discussed.

TVA-based assessment of visual attentional functions in developmental dyslexia.

There is an ongoing debate whether an impairment of visual attentional functions constitutes an additional or even an isolated deficit of developmental dyslexia (DD). Especially performance in tasks that require the processing of multiple visual elements in parallel has been reported to be impaired in DD. We review studies that used parameter-based assessment for identifying and quantifying impaired aspect(s) of visual attention that underlie this multi-element processing deficit in DD. These studies used the mathematical framework provided by the "theory of visual attention" (Bundesen, 1990) to derive quantitative measures of general attentional resources and attentional weighting aspects on the basis of behavioral performance in whole- and partial-report tasks. Based on parameter estimates in children and adults with DD, the reviewed studies support a slowed perceptual processing speed as an underlying primary deficit in DD. Moreover, a reduction in visual short term memory storage capacity seems to present a modulating component, contributing to difficulties in written language processing. Furthermore, comparing the spatial distributions of attentional weights in children and adults suggests that having limited reading and writing skills might impair the development of a slight leftward bias, that is typical for unimpaired adult readers.

Parameter-based assessment of disturbed and intact components of visual attention in children with developmental dyslexia.

People with developmental dyslexia (DD) have been shown to be impaired in tasks that require the processing of multiple visual elements in parallel. It has been suggested that this deficit originates from disturbed visual attentional functions. The parameter-based assessment of visual attention based on Bundesen's () theory of visual attention allows one to identify and quantify the underlying deficits. The present study provides the first groupwise comparison between children with DD (n = 12; mean age 9.84 years) and typically developing children (n = 12; mean age 9.87 years) with regard to intact and disturbed components of visual attention. From the performance on whole- and partial-report tasks, we derived individual parameter estimates of four different parameters: visual processing speed, storage capacity of visual short-term memory (VSTM), laterality of attentional weighting and efficiency of top-down control. Groupwise comparisons revealed that general attentional resources, processing speed and VSTM storage capacity, are impaired in children with DD compared to typically developing children. In contrast, selectivity parameters, laterality of attentional selection and attentional top-down control did not differ between these groups. Relating the current findings to previous results, obtained in highly comparable methodological settings, from single cases of children with DD, and from a group of adults with DD, we conclude that slowed perceptual processing speed is a primary visual attentional deficit in DD. Furthermore, reduced VSTM storage capacity seems to modulate the difficulties in written language processing imposed by the disorder.