June 2006
Volume 6, Issue 6
Free
Vision Sciences Society Annual Meeting Abstract  |   June 2006
Measuring the timecourse of guidance in visual search
Author Affiliations
  • Evan M. Palmer
    Brigham & Women's Hospital, and Harvard Medical School
  • Michael J. Van Wert
    Brigham & Women's Hospital
  • Todd S. Horowitz
    Brigham & Women's Hospital, and Harvard Medical School
  • Jeremy M. Wolfe
    Brigham & Women's Hospital, and Harvard Medical School
Journal of Vision June 2006, Vol.6, 443. doi:10.1167/6.6.443
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      Evan M. Palmer, Michael J. Van Wert, Todd S. Horowitz, Jeremy M. Wolfe; Measuring the timecourse of guidance in visual search. Journal of Vision 2006;6(6):443. doi: 10.1167/6.6.443.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

In search tasks, observers can guide attention to likely targets based on features such as color and orientation. Does guidance develop over time during search or does it act as a fixed filter, present from the start of a trial? We measured the timecourse of guidance by presenting guiding color information prior to the search array. Observers searched for a T among Ls in three conditions: Large and Small conditions consisted of monochromatic displays of 24 or 4 items, respectively; Mixed condition had 4 items of the target color and 20 of another color. Colored placeholders provided guiding information at a variable stimulus onset asynchrony (SOA) prior to appearance of the search array. Target color was either consistent or varied within a block. If guidance develops over time, we would expect that Mixed condition reaction times (RTs) would start off near Large condition RTs when SOA was 0 ms, then drop to asymptote at the Small condition RTs with increasing SOA. Results showed that when target color was consistent within a block, Mixed and Small conditions had comparable RTs from 0 ms SOA on, indicating immediate, sustained guidance. However, when target color varied within a block, RTs were consistent with guidance developing over 200 ms. We conclude that guidance takes 200 ms or less to become effective and, once established, acts like a filter to segregate displays immediately.

Palmer, E. M. Van Wert, M. J. Horowitz, T. S. Wolfe, J. M. (2006). Measuring the timecourse of guidance in visual search [Abstract]. Journal of Vision, 6(6):443, 443a, http://journalofvision.org/6/6/443/, doi:10.1167/6.6.443. [CrossRef]
Footnotes
 AFOSR grant #F49620-01-1-0071 to JMW and NIMH grant #65576 to TSH.
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