From Stimulus to Representation: Target Identification in Rapid Serial Visual Presentation

This dissertation investigated the relationship between target identification and temporal integration with three studies. Rapid serial visual presentation tasks were used to investigate empirical questions, where two targets are embedded in a set of distracters, and the task is to identify targets. Temporal integration is a phenomenon that temporally separated targets fall into the same perceptual episode. The first study investigated whether a change in low-level stimulus features (color/contrast) influences temporal attention and integration. The results showed that a categorical change of target color decreases the competition between targets resulting in better target identification and more frequent integrations. Besides, the study confirmed the literature that high contrast stimuli mask low contrast stimuli if their temporal proximity is close. The second study investigated if Gestalt properties influence the temporal binding of targets and target identification. In addition to studies that show parts of objects are grouped in space, the second study showed that if temporally separated targets form a figure, their integrated percepts and identifications are facilitated. Lastly, how a change in mental state with consumption of cocoa flavanols, which increases blood flow in brain arteries, influences target identification and integrations were investigated. There was no effect of cocoa flavanols on temporal attention and integration. In addition, the study showed that cocoa flavanols improve the efficiency of visual search. In sum, target identification and integration are both influenced by exogenous stimuli properties and by flavanol-induced changes in mental state, and often also in a similar direction.