Detektion und Identifikation von Figur-Grund-Unterschieden: Psychophysik, Elektrophysiologie und Magnetresonanztomographie

The dissertation deals with psychophysical and neural properties of figure-ground-segregation in humans i) using two types of visual cues (orientation and spatial frequency) and ii) two types of tasks (detection and identification). The effect of visual cue combination is investigated separately for detection and identification using psychophysical and ERP measurements to evaluate how the combination itself and/or the perceived figure saliency influence the ERP. As a result, it was found in both studies that the neural response at 200 ms reflected saliency-changes rather than physical cue configuration. The comparison of detection and identification was investigated by combining psychophysics and fMRI. Pronounced differences between detection and identification were found i) in the psychophysical thresholds and the reaction times, and ii) in the BOLD responses. In summary, the results indicate at least partly separated cortical mechanisms for object detection and identification.