Visual Search for a Tilted Target: Tests of Spatial Uncertainty Models

We report that spatial cueing of a parafoveal target in the presence of distractors enhances orientational acuity for that target. When no distractors were present, orientation thresholds were in the range 1–4°. For long exposure times, distractors increased threshold by the amount predicted from a winner-takes-all spatial uncertainty model. For short (100-msec) exposures followed by a random dot mask, the rise in threshold with distractors was considerably greater than that predicted from spatial uncertainty. For brief exposures the effect of distractors was greater when the target and distractors were spatially crowded rather than widely spaced. Adding a tilt to the distractors in the opposite direction to the target increased thresholds still further. Cueing the target with a spatial pointer decreased the effect of distractors, even when they were crowded. We suggest that when attention cannot be appropriately focused, discrimination is carried out by a relatively coarse texture analyser, which averages over several elements, and that focused attention permits the analysis of the target over a smaller area of space.

[1]  P. Cavanagh,et al.  Attentional resolution and the locus of visual awareness , 1996, Nature.

[2]  M. J. Morgan,et al.  Detection of orientationally multimodal textures , 1995, Vision Research.

[3]  H. Pashler,et al.  Negligible Effect of Spatial Precuing on Identification of Single Digits , 1994 .

[4]  K. Nakayama,et al.  Stimulus discriminability in visual search , 1994, Vision Research.

[5]  J. Palmer.  Set-size effects in visual search: The effect of attention is independent of the stimulus for simple tasks , 1994, Vision Research.

[6]  M. Cheal,et al.  Allocation of Attention in Texture Segregation, Visual Search, and Location-Precuing Paradigms , 1994, The Quarterly journal of experimental psychology. A, Human experimental psychology.

[7]  J. Palmer,et al.  Measuring the effect of attention on simple visual search. , 1993, Journal of experimental psychology. Human perception and performance.

[8]  J. Wolfe.  “Effortless” texture segmentation and “parallel” visual search are not the same thing , 1992, Vision Research.

[9]  Norma Graham,et al.  Nonlinear processes in spatial-frequency channel models of perceived texture segregation: Effects of sign and amount of contrast , 1992, Vision Research.

[10]  H. C. Nothdurft,et al.  Texture segmentation and pop-out from orientation contrast , 1991, Vision Research.

[11]  M. Cheal,et al.  Central and Peripheral Precuing of Forced-Choice Discrimination , 1991, The Quarterly journal of experimental psychology. A, Human experimental psychology.

[12]  H. Hawkins,et al.  Visual attention modulates signal detectability. , 1990, Journal of experimental psychology. Human perception and performance.

[13]  P Perona,et al.  Preattentive texture discrimination with early vision mechanisms. , 1990, Journal of the Optical Society of America. A, Optics and image science.

[14]  M. Morgan,et al.  Perceived diagonals in grids and lattices , 1989, Vision Research.

[15]  J. Duncan.  Boundary Conditions on Parallel Processing in Human Vision , 1989, Perception.

[16]  J. Duncan,et al.  Visual search and stimulus similarity. , 1989, Psychological review.

[17]  E. Adelson,et al.  Early vision and texture perception , 1988, Nature.

[18]  D G Pelli,et al.  Uncertainty explains many aspects of visual contrast detection and discrimination. , 1985, Journal of the Optical Society of America. A, Optics and image science.

[19]  James R. Bergen,et al.  Parallel versus serial processing in rapid pattern discrimination , 1983, Nature.

[20]  R. L. Valois,et al.  The orientation and direction selectivity of cells in macaque visual cortex , 1982, Vision Research.

[21]  D. P. Andrews,et al.  APE: Adaptive probit estimation of psychometric functions , 1981 .

[22]  M. Posner,et al.  Attention and the detection of signals. , 1980, Journal of experimental psychology.

[23]  G Westheimer,et al.  The spatial sense of the eye. Proctor lecture. , 1979, Investigative ophthalmology & visual science.

[24]  Valerie Townsend,et al.  Voluntary Attention in Peripheral Vision and its Effects on Acuity and Differential Thresholds , 1968, The Quarterly journal of experimental psychology.

[25]  D. Hubel,et al.  Receptive fields of single neurones in the cat's striate cortex , 1959, The Journal of physiology.

[26]  Gregory Bock,et al.  Higher-order processing in the visual system , 1994 .

[27]  O. Braddick.  Visual hyperacuity. , 1984, Nature.

[28]  J. Townsend.  Theoretical analysis of an alphabetic confusion matrix , 1971 .

[29]  J. Gaddum.  Probit Analysis , 1948, Nature.