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Threshold recognition of phantom-contour objects requires constant contrast velocity

Threshold recognition of phantom-contour objects requires constant contrast velocity Recognition of phantom objects—those with contours defined by rapid contrast reversal of adjacent fields of dark and light random dots—was investigated under conditions of abrupt or ramped onset and offset. Discrimination contrast thresholds were determined for a random-dot phantom letter in four possible orientations. For abrupt onset or offset, thresholds were almost independent of the duration of presentation time, over a range that varied tenfold, from 34–340 msec. However, when the onset and offset were shaped by a triangular envelope, thresholds were raised, so that form blindness occurred even when peak dot contrasts exceeded 60%. Also under ramped onset and offset conditions, threshold contrast varied strictly linearly with stimulus duration in all subjects, suggesting a new construct—contrast velocity, the rate of change of contrast critical for phantom-object recognition. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Attention, Perception, & Psychophysics Springer Journals

Threshold recognition of phantom-contour objects requires constant contrast velocity

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References (24)

Publisher
Springer Journals
Copyright
Copyright © 2007 by Psychonomic Society, Inc.
Subject
Psychology; Cognitive Psychology
ISSN
1943-3921
eISSN
1532-5962
DOI
10.3758/BF03193941
Publisher site
See Article on Publisher Site

Abstract

Recognition of phantom objects—those with contours defined by rapid contrast reversal of adjacent fields of dark and light random dots—was investigated under conditions of abrupt or ramped onset and offset. Discrimination contrast thresholds were determined for a random-dot phantom letter in four possible orientations. For abrupt onset or offset, thresholds were almost independent of the duration of presentation time, over a range that varied tenfold, from 34–340 msec. However, when the onset and offset were shaped by a triangular envelope, thresholds were raised, so that form blindness occurred even when peak dot contrasts exceeded 60%. Also under ramped onset and offset conditions, threshold contrast varied strictly linearly with stimulus duration in all subjects, suggesting a new construct—contrast velocity, the rate of change of contrast critical for phantom-object recognition.

Journal

Attention, Perception, & PsychophysicsSpringer Journals

Published: Nov 22, 2010

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