The Sensitivity of Binocular Rivalry Suppression to Changes in Orientation Assessed by Reaction-Time and Forced-Choice Techniques

Abstract

Binocular rivalry was induced between two orthogonal square-wave gratings of the same spatial frequency, luminance, contrast, and field size, presented dichoptically. One of the gratings could be instantly replaced by a third grating differing only in orientation. In one experiment subjects were required to respond as soon as an orientation change was noticed, and to withhold response to catch trials (no orientation change). When orientation changes were made to the visible grating, reaction time was found to be a U-shaped function of the magnitude of orientation change. When orientation changes were made to the grating undergoing binocular-rivalry suppression, an overall increase in reaction time was found with the increase being greater for large orientation changes (an asymmetrical U-shaped function). In another experiment subjects were required to detect the direction of a change in orientation in a two-alternative forced-choice procedure. Thresholds were thus obtained for 75% correct performance. It was found that thresholds for orientation changes made to the visible and invisible fields were identical from 20 degrees to 70 degrees orientation change. Outside this range thresholds were higher when orientation changes were made to the field suppressed by binocular rivalry. It is argued that the orientation functions obtained in the two experiments may represent incomplete suppression of either form or transient information during binocular rivalry.

Pre-stimulus pattern of activity in the fusiform face area predicts face percepts during binocular rivalry

“…In contrast, other evidence supports the view of low-level and eye-based rivalry (Blake et al, 1981;Check, 1968, 1972;Wales and Fox, 1970;Fukuda, 1981;O'Shea and Crassini, 1981;Smith et al, 1982;O'Shea, 1987;Polonsky et al, 2000;Tong and Engel, 2001;Lee et al, 2005;Meng et al, 2005;Moutoussis et al, 2005;Wunderlich et al, 2005).…”

Orientation-tuned suppression in binocular rivalry reveals general and specific components of rivalry suppression

“…The ratio of dominance to suppression thresholds, when subtracted from unity, gives an index that ranges from zero (no suppression) to 1.0 (complete suppression). Visual sensitivity for detecting probes during suppression is reduced by about È0.3-0.5 log units relative to when the image is dominant (Blake & Fox, 1974;Ooi & Loop, 1994;O'Shea & Crassini, 1981), although suppression is generally greater for more complex images (Alais & Melcher, 2007;Alais & Parker, 2006;Nguyen et al, 2003). This typical reduction in sensitivity during suppression corresponds to a suppression strength of È0.41-0.52.…”

The depth and selectivity of suppression in binocular rivalry

“…In the spatial domain, three previous studies (Blake & Fox, 1974b;O'Shea & Crassini, 1981;Walker & Powell, 1979) have investigated whether a change in the spatial frequency or orientation of a suppressed stimulus is sufficient to break suppression. All three studies used a replacement procedure to introduce the stimulus change: The suppressed conditioning stimulus, a square-wave grating, was replaced by another stimulus differing only in spatial frequency or orientation.…”

“…This is the approach we have taken, and it is also the method used by O'Shea and Crassini (1981) in their second experiment. They still used a replacement procedure, but the duration of the replacement grating was adjusted so that the subjects indicated its orientation with a specified accuracy.…”