Backward masking is not required to elicit the central performance drop.
In some circumstances, texture discrimination performance peaks in the parafovea rather than at the fovea. Kehrer (1987) referred to this phenomenon as the central performance drop (CPD). In most studies showing the CPD, task performance has been limited by a backward mask. Morikawa (2000) has argued that in these studies the backward mask was critical to the emergence of the CPD. In three studies we use textures comprising left and right oblique line segments and limit performance by manipulating the orientation variability within the foreground and background textures. Using this method we demonstrate that significant CPDs emerge whether or not there is a backward mask. We conclude that in past studies of the CPD the backward mask functioned primarily as a source of spatial noise and that its temporal relation to the texture display is not critical to the emergence of the CPD.
Department of Psychology, Concordia University, 7141 Sherbrooke Street West, Montreal, Quebec, Canada H4B 1R6.
Cindy
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Potechin
Rick
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Gurnsey
D006801:Humans; D008954:Models, Biological; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010470:Perceptual Masking / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D012160:Retina / Q000502:physiology; D014794:Visual Fields / Q000502:physiology; D014795:Visual Pathways / Q000502:physiology*