18 avril 2012 - Conférence de Joseph Krummenacher : Mechanisms of Dimension-based Selection in Visual Search: Models and Methods

Mechanisms of Dimension-based Selection in Visual Search: Models and Methods

Joseph Krummenacher
Département de psychologie, Université de Fribourg

Mercredi 18 avril - 12h15 - Uni Mail, salle MR060

In order to efficiently plan and control our behavior we need to constantly select information. Negotiating obstacles while walking, interpreting facial features while talking to someone, or checking the text while typing all require the prioritized processing of a selection of data provided by the senses and the deselection of other sensory data. In the visual domain, sensory information may be selected on the basis of visual features or feature dimensions; for example, an object might be selected because it differs from other objects by its color, shape or size.

In my presentation I discuss recent results of investigations into the issue of whether mechanisms of dimension-based selection can be modulated at an early processing stage before information is selected. Generally, it is assumed that early processing stages - involved in the extraction of visual information from the environment and the generation of initial representations - are immune to effects of previously processed stimulus features or to foreknowledge stored in memory.

In the all the experiments, participants completed a visual search task in which they indicated whether a target object was present or absent in an array of distractor objects. Various methods of reaction time analysis were employed to infer the exact nature of the mechanisms mediating the decision. The results show that performance is significantly affected by stimulus and task characteristics. The modulations can be shown to arise at the level of dimension-based stimulus representations.