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Psychol Res (1981) 43:259--275 Springer-Vertag-1981

Summary: Psychol Res (1981) 43:259--275
PerceptualSamplingof OrthogonalStraight Line Features*
James T. Townsend**, Gary G. Hu, and F. Gregory Ashby
Department of Psychological Sciences, Purdue University, West Lafayette, IN 47907, USA
Summary. Among mathematical models of visual confusion of letters and similar
material, those that posit a feature detection process have been especially popu-
lar. The present study provides direct tests of several of the central assumptions
of such models with feature-stimuli composed of the blank, one of two straight
line features, or both line.features positioned at a right angle. In one condition,
the two features were connected when they appeared together, whereas in the
other condition they were separated by a gap. A model which makes the strong
assumptions that the features are sampled ('detected') independently and then
reported in a direct, unbiased fashion, performed acceptably in both conditions.
Feature dependency models and those positing a biased decision process were
ruled out on the basis of poor fits or lack of parsimony. The perceptibility (d')
of a specific feature depended on the stimulus that contained it in the Gap con-
dition but not in the Connected condition. The relative perceptibility of the
horizontal vs in the vertical features was also different in the Gap vs Connected
conditions. The results were compared with other recent studies, including ones


Source: Ashby, F. Gregory - Department of Psychology, University of California at Santa Barbara


Collections: Biology and Medicine; Computer Technologies and Information Sciences