Three Paradigms for Selective Attention in Vision

Abstract

The first study investigated the underlying mechanisms of selective attention and the extent of which an irrelevant stimulus is processed as well as the nature of this processing. A spatial filtering paradigm was used to quantify the effects of an irrelevant stimulus in a selective attention task (Chapter 1). The results have shown that if the task requires observers to constrain their attention to a small spatial area, a blocking mechanism is used for selection. In blocking, unattended stimuli are blocked from further processing. If the task requires observers to distribute their attention to a large spatial area, an attenuation mechanism is used for selection. In attenuation, the unattended stimuli are reduced in strength, but at high intensities (e.g., high contrast), they can still have access to further processing. In the second study, the same paradigm was used with the combination of many-to-one response mapping of the flanker paradigm to unravel the nature of the effects of irrelevant stimuli on the judgment of a relevant stimulus (Chapter 2). The results have shown that the effects of irrelevant stimuli are consistent with a failure of selection, which is an example of blocking mechanism.