Quick Search:

uzh logo
Browse by:
bullet
bullet
bullet
bullet

Zurich Open Repository and Archive

Permanent URL to this publication: http://dx.doi.org/10.5167/uzh-47136

Kotowicz, A; Rutishauser, U; Koch, C (2010). Time course of target recognition in visual search. Frontiers in Human Neuroscience, 4:31.

[img]
Preview
PDF
2MB

View at publisher

Abstract

VISUAL SEARCH IS A UBIQUITOUS TASK OF GREAT IMPORTANCE: it allows us to quickly find the objects that we are looking for. During active search for an object (target), eye movements are made to different parts of the scene. Fixation locations are chosen based on a combination of information about the target and the visual input. At the end of a successful search, the eyes typically fixate on the target. But does this imply that target identification occurs while looking at it? The duration of a typical fixation ( approximately 170 ms) and neuronal latencies of both the oculomotor system and the visual stream indicate that there might not be enough time to do so. Previous studies have suggested the following solution to this dilemma: the target is identified extrafoveally and this event will trigger a saccade towards the target location. However this has not been experimentally verified. Here we test the hypothesis that subjects recognize the target before they look at it using a search display of oriented colored bars. Using a gaze-contingent real-time technique, we prematurely stopped search shortly after subjects fixated the target. Afterwards, we asked subjects to identify the target location. We find that subjects can identify the target location even when fixating on the target for less than 10 ms. Longer fixations on the target do not increase detection performance but increase confidence. In contrast, subjects cannot perform this task if they are not allowed to move their eyes. Thus, information about the target during conjunction search for colored oriented bars can, in some circumstances, be acquired at least one fixation ahead of reaching the target. The final fixation serves to increase confidence rather then performance, illustrating a distinct role of the final fixation for the subjective judgment of confidence rather than accuracy.

Citations

6 citations in Web of Science®
9 citations in Scopus®
Google Scholar™

Altmetrics

Downloads

53 downloads since deposited on 04 Mar 2011
12 downloads since 12 months

Detailed statistics

Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Institute of Neuroinformatics
DDC:570 Life sciences; biology
Language:English
Date:1 January 2010
Deposited On:04 Mar 2011 15:51
Last Modified:27 Nov 2013 19:47
Publisher:Frontiers Research Foundation
Number of Pages:0
ISSN:1662-5161
Publisher DOI:10.3389/fnhum.2010.00031
PubMed ID:20428512

Users (please log in): suggest update or correction for this item

Repository Staff Only: item control page