Dimension Weighting Re-visited

Colloquium
Date: 
15 May 2013
Begin time: 
18:00
Room: 
ZiF (Long Table Room)

Abstract

One central issue in visual pop-out search concerns which processes are operating re-attentively, i.e., prior to focal-attentional target selection, and which post-selectively, i.e., leading up to the required response. In this presentation, we will review behavioral and electrophysiological evidence that we have collected recently, which favors a salience-based selection model in which salience computations are subject to (primarily) dimension-dependent inter-trial, i.e., bottom-up, and top-down modulations (the ?dimension-weighting? account). This notion also goes a long way to explain the capture of attention by irrelevant singleton distractors: our evidence suggests that capture is subject to (largely dimension-based) top-down control, with control processes dynamically adjusting interference from the distractor dimension on a fine temporal scale. Beyond this, our evidence shows that similar modulations also operate at post-selective stages of processing, and carry over across tasks (e.g., detection, localization, compound task) that share similar component processes (the ?multiple-weighting-systems? hypothesis). While post-selective processing, i.e., the time to attentionally analyze the target and select an appropriate response, is heavily dependent on the task, pre-selective processes are not influenced by the task demands. One further issue to be addressed concerns under which search conditions inter-trial effects are feature-specific, as compared to dimension-specific in nature. Our evidence suggests that when displays are sparse, search work via a feature-based mode; but when the same displays are made dense (enabling feature contrast interactions), search operates in singleton-mode and this is associated with dimension-based effects. Finally, we present evidence that the same principles that govern singleton feature search also extend to explaining search for single conjunction targets.