Lay summary
The project is aimed at investigating mechanisms of visual selection using, in an integrative approach, methods of cognitive experimental psychology (reaction times), psychophysiology (event-related potentials) and eye movement recording. The methods are applied to compare visual search performance in participants with disturbances of selective attention to the results of unimpaired observers. The project involves four research foci.Focus 1 investigates the relationship between attention and eye movements in feature and compound visual search tasks. Own research shows that dimensional and spatial weighting processes modulate search performance differently in these two search types. Reaction time and eye movement analyzes are employed to investigate the relationship between the mechanisms underlying the allocation of focal attention and those controlling saccadic eye movements. Dimension-based and spatial effects will be analyzed with respect to early (e.g., saccade latency) and late (e.g., fixation duration) processing stages.Focus 2 employs hidden Markov models to investigate the mechanisms underlying intertrial transition effects. It is generally assumed that reaction time modulations reflected in mean reaction times are due to trial-by-trial modulations of processing resources. The project aims at investigating this claim by comparing experimental data with model predictions.Focus 3 is aimed at identifying the component mechanisms of attentional selection altered in attention deficit disorders and autistic impairments. In a systematic investigation of the component processes of visual attention - working memory, processing speed, top-down control - selective performance in observers with and without attention disorders is compared. People suffering from autistic disturbances have repeatedly been shown to outperform normal controls in attention tasks. The component processes underlying this search performance advantage are investigated in participants with Asperger's syndrome to identify component mechanisms giving rise to the benefit.Focus 4 uses electroencephalography (EEG) to assess, with high temporal resolution, the processes underlying signal integration within and across modalities in healthy and impaired observers in selection tasks.The proposed research is expected to contribute to the understanding of the component mechanisms underlying the control of selective information processing. By comparing unimpaired and impaired performances, theoretical constraints of experimental psychology and cognitive neuropsychology will be met in order to extend the theoretical models proposed to explain the key human ability of information selection.