Dean G Purcell

Publications (31) View all

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  Available from: Dean G Purcell

  Article: Nonmonotone backward masking functions and brightness reversals.

  Alan L Stewart, Dean G Purcell, Roger S Pinkham
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  ABSTRACT: Increasing the target-field luminance aids detection for a simultaneously presented black target disc and a black masking annulus. At an intermediate interval separating the onset of the target from the mask, increasing the target-field luminance reduces target detection. This decrease in performance occurs with both temporal and spatial forced choice tasks. With a spatial forced choice, an observer's performance can fall below chance. We associate below-chance performance with a brightness reversal of the black target disc, such that the target disc appears brighter than its surround. The occurrence of brightness reversals follows from our model of the Broca-Sulzer effect, and nonmonotone masking functions result from a generalization of luminance summation.
  Attention Perception & Psychophysics 07/2011; 73(7):2180-96. · 2.04 Impact Factor
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  Available from: Dean G Purcell

  Article: Still another confounded face in the crowd.

  Dean G Purcell, Alan L Stewart
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  ABSTRACT: Experiments using schematic faces developed by Öhman (Öhman, Lundqvist, & Esteves, 2001) seem to document an anger-superiority effect, although we have come to question these experiments. Our work shows that the low-level features of these schematic faces interact with the face's surround to produce effects that have been attributed to facial affect. Using relatively neutral faces that preserved the feature and surround spatial relationships of angry and happy schematic faces, we produced reaction times (RTs) that were indistinguishable from those found with angry and happy faces. We also found that the target face's position within the crowd determined the magnitude of the advantage for angry faces as well as for relatively affect-neutral faces. Removing the facial surround reduces the advantage for angry faces, largely by improving performance on happy faces. There was an apparent small advantage for angry features without a surround. Öhman faces avoid the problems associated with modified grayscale faces only to introduce an equally troubling confound.
  Attention Perception & Psychophysics 11/2010; 72(8):2115-27. · 2.04 Impact Factor
• Article: The object-detection effect: Configuration enhances perception

  Dean G. Purcell, Alan L. Stewart
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  ABSTRACT: Line drawings used by Weisstein and Harris (1974) are seen as box-like three-dimensional figures if the lines are arranged properly. A flat two-dimensional pattern is seen when these same lines are disarranged. A target line contained within the three-dimensional figure is identified more readily than is the same line contained within a two-dimensional figure. This finding was extended in the present experiments: The three-dimensional stimulus was detected more quickly than the two-dimensional stimulus, under conditions of visual backward masking. Three-dimensional stimuli were also classified more quickly than two-dimensional stimuli. Just as with the face-detection effect and the word-detection effect, object detection can be affected by the form of the visual stimulus.
  Attention Perception & Psychophysics 04/1991; 50(3):215-224. · 2.04 Impact Factor
• Article: Probing "pop-out": Another look at the face-in-the-crowd effect.

  Carol Hampton, Dean G. Purcell, Louis Bersine, Christine H. Hansen, et al
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  ABSTRACT: Three experiments with 41 human Ss examined C. H. Hansen and R. D. Hansen's (see record 1988-32617-001) face-in-the-crowd effect (FICE [i.e., search time to locate a face within an array of other faces depends on the expression of the target face]). FICE was replicated for 9-face but not for 4-face crowds. Contrary to Hansen and Hansen's "pop-out" hypothesis to explain FICE, the position of the target face within the crowd did have an effect on reaction time (RT), suggesting that Ss were scanning the face array to locate the target face. Findings are consistent with the literature on the perception of facial expression that propose FICE to be produced by the crowds scanned rather than by the target. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
  Bulletin of the Psychonomic Society 10/1989;
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  Available from: Alan L Stewart

  Article: The face-detection effect: Configuration enhances detection

  Dean G. Purcell, Alan L. Stewart
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  ABSTRACT: We have found that a picture of a face is more easily detected than is a pattern of arbitrarily rearranged facial features. An upright face is also more detectable than an inverted face. Using two-alternative forced-choice visual masking paradigms, we have found that this face-detection effect (FDE) can be produced with line drawings and with photocopies of a picture of a face. Our results suggest that a face, as an organized, meaningful pattern, is a more potent stimulus than an arbitrary assemblage of the same visual features. It may be that the FDE is a visual configuration effect. Previous visual configuration effects have been documented only with recognition responses. The FDE, by contrast, documents a configuration effect that affects the detectability of a stimulus.
  Attention Perception & Psychophysics 04/1988; 43(4):355-366. · 2.04 Impact Factor