Local Processes in Preattentive Feature Detection

William F. Bacon, Howard E. Egeth

Research output: Contribution to journalArticlepeer-review

91 Scopus citations


Sagi and Julesz (1987) claimed that for a target to be detected preattentively, it must be within some small critical distance of a nontarget. The independent effects of separation and display size, which were confounded in the Sagi and Julesz experiments, were examined. Experiments 1 and 2 revealed that in tasks requiring search for a color-defined target, target-nontarget separation had no effect on reaction time (RT). Display size, however, was inversely related to RT. Experiment 3 ruled out the possibility that the decreasing function of RT with display size was due to arousal caused by higher display luminance. When nontarget grouping was inhibited, (Exp. 4) it was found that RT no longer decreased with increasing display size. This suggests that nontarget grouping may have been the cause of the improved performance at larger display sizes. Experiments 5 and 6 extended the results to line segments, the stimuli used by Sagi and Julesz.

Original languageEnglish (US)
Pages (from-to)77-90
Number of pages14
JournalJournal of Experimental Psychology: Human Perception and Performance
Issue number1
StatePublished - Feb 1991

ASJC Scopus subject areas

  • Experimental and Cognitive Psychology
  • Arts and Humanities (miscellaneous)
  • Behavioral Neuroscience


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