Lay summary
The project aims at investigating the mechanisms common to the control of selective visual attention and eye movements. Cognitive, neuropsychological and neuroscience research suggests that selective visual attention and eye movements are controlled by networks of brain areas that show large overlap.Own behavioral research using visual search tasks has contributed to a cognitive model of the processes underlying dimension-based selection assuming that search is based on a saliency representation that guides focal attention. Mechanisms of saliency generation and integration were shown to be susceptible to stimulus-driven (bottom-up) and knowledge-based (top-down) modulations. Bottom-up and top-down effects are explained by implicit (repetition vs. change of stimulus characteristics) or explicit (semantic cue) shifts of processing resources.A first objective is to investigate the bottom-up and top-down modulations of eye movement parameters (saccade latencies, fixation durations, location errors, prevalence of eye movements) in a number of visual search tasks (feature, conjunction, and compound search).Comparisons of the patterns of manual reaction times and oculomotor latencies are expected to reveal whether visual selection and eye movements are controlled by the same or different saliency representations. Dependent on whether there is overlap in the result patterns or not, the brain areas likely to underlie the relevant control mechanisms can be identified. Theoretical analysis is guided by recent reports of brain areas underlying spatial visual attention (e.g., Corbetta et al., 2002) and eye movement control (e.g., Munoz et al., 2004). A second objective is the application of empirical and theoretical results to the issue of attention impairments. People suffering from Attention Deficit Hyperactivity Disorder (ADHD) and people with difficulties in social interactions such as those diagnosed with Asperger's syndrome are of particular interest for the understanding of selective processes. Individuals diagnosed with high-functioning autism or Asperger's syndrome have been reported to show advantages in visual search tasks in comparison to normal observers; the same may also be true for people with ADHD. Behavioral measures and eye movement parameters of a selection of visual search tasks are compared with the results of investigations of unimpaired participants. The project is expected to contribute significantly to the issue of which aspects of selective attention and eye movements are governed by the same or different underlying networks. Further, brain areas likely to underlie attentional disorders are expected to be identified.