Event Abstract

Non-selective and Selective Processing in Human Visual Search

  • 1 Harvard Medical School, United States
  • 2 Brigham and Women's Hospital, United States

Human’s ability to understand complex visual scenes and effectively find visual targets involves rapid assessment of “gist” of the image as well as scrutiny of the image details. When humans search for visual targets in a complex scene it is thought that they engage two types of processing (non-selective and selective processing)(Wolfe et al., 2011, Evans et al., 2011) that involve deployment of two types of spatial attention (distributed and focused) (Treisman, 2006, Chong & Evans, 2011). I will describe two very relevant phenomenon that affect and guide human visual search in real world scenes involving the two types of processing. One part of the research investigating non-selective processing will show that initial gist processing is based on extraction by the observers of global structural and statistical regularities automatically and flexibly during the first 20-250 milliseconds of visual search. The second part of research investigating selective processing will demonstrate a critical role of visual target prevalence on real world searches such as medical screening. In hard visual search tasks that are performed every day in the clinic we find greatly elevated miss errors at low prevalence as compared to lower miss errors when then target appears at least 50% of the time (“high prevalence”). These results indicate that the low prevalence of disease is actually an important contributor to missed detection of cancer in medical screening. This prevalence effect is adaptive in most real world settings, where an observer should be reluctant to assert that she has found a very rare target.


This research was funded by Ruth L. Kirschstein National Research Service Award Grant F32EY019819-01 to Karla K. Evans.

Keywords: Attention, non-selective processing, Prevalence, scene categorization, selective processing, visual search

Conference: Tenth International Congress of Neuroethology, College Park. Maryland USA, United States, 5 Aug - 10 Aug, 2012.

Presentation Type: Invited Symposium (only for people who have been invited to a particular symposium)

Topic: Sensory: Vision

Citation: Evans KK (2012). Non-selective and Selective Processing in Human Visual Search. Conference Abstract: Tenth International Congress of Neuroethology. doi: 10.3389/conf.fnbeh.2012.27.00015

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Received: 03 Apr 2012; Published Online: 07 Jul 2012.

* Correspondence: Dr. Karla K Evans, Harvard Medical School, Cambridge, Massachusetts, 02139, United States, karla.evans@york.ac.uk