Vorschau

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Abstract

This doctoral thesis examines the interaction of cognitive, motivational and emotional processes during visual search. Theories of visual search make contradictory assumptions about the interaction between bottom-up and top-down control during parallel visual search: Whereas the stimulus-driven capture account (Theeuwes, 2010) postulates that parallel search is solely controlled by bottom-up processes, the dimension weighting account (Zehetleitner, Goschy, & Müller, 2012) assumes that top-down control is possible during this early phase of visual search. This doctoral thesis argues that both theories neglect the motivation of the observer to implement top-down control. Three experiments test the hypothesis that observers’ intentions guide parallel search if the observers are motivated to engage in effortful top-down control. The results partly confirm the hypothesis and show that a purely cognitive theory of visual search delivers an incomplete model of how observers control the search process. A fourth experiment examines the effect of emotional facial stimuli on visual search. According to the very influential threat superiority hypothesis (Öhman, Lundqvist, & Esteves, 2001) threatening faces capture attention during parallel search via bottom-up control. This doctoral thesis analyses various methodological weaknesses of the experiments conducted to test the threat superiority hypothesis and argues that the assumed bottom-up capture by emotional stimuli is in fact top-down mediated. A new visual search task is developed which provides a more valid test of bottom-up capture by emotional faces. The results of the fourth experiment show that emotional stimuli only distract attention if they are relevant for the target of search. Therefore, emotional stimuli do not automatically capture attention. The implications of the studies for the theories and methods of visual search are discussed.