The assessment of motor control in sighting dominance using an illusion decrement procedure

Abstract

Walls (1951) proposed that perceptual asymmetries between the sighting dominant and the nonsighting dominant eyes were based upon differences in the monitoring of eye movements. The present research explored this hypothesis in the context of an illusion decrement paradigm. Since illusion decrement seems to occur only under conditions of free eye-movement inspection, it was reasoned that any motoric asymmetries would manifest themselves through differences in the rate and extent of decrement. These predictions were partially confirmed. The sighting eye manifested greater illusion decrement, but the effect remained specific to conditions where both eyes were stimulated. In addition, asymmetries in the interocular transfer of illusion decrement were found to favor the sighting dominant eye.

Is visual illusion decrement based on selective adaptation?

“…In the present experiment, a brief3-min decrement exposure was used, unlike most previous research, in which 5-to lo-min exposures were used (Coren & Girgus, 1974;Girgus et al, 1975;Porac & Coren, 1977. Thus, the absolute duration of the adaptation phase was equrvalent to the 2 to 3 min used in selective adaptation paradigms (Long et al, 1983;Toppino & Long, 1987).…”

“…All observers had tested visual acuity in the normal range without correction and all were right-eyed sighting dominant as assessed by procedures devised by Porac and Coren (1981). The sighting-dominance testing was included to allow control of possible sighting-dominance effects in the decrement and transfer stages of the experiment (see Porac & Coren, 1977).…”

“…It occurs in cyclopean viewing (Coren & Porac, 1984) and demonstrates interocular transfer (Porac & Coren, 1977). In addition, decrement reductions transfer between different MullerLyer variants that share similar features (Coren & Girgus, 1974;Porac & Coren, 1985).…”

The relationship between sighting dominance and the fading of a stabilized retinal image

“…While these neural explanations seem to have some apparent cogency, one must not rule out the possibility that the relative resistance to fading of the stabilized retinal image displayed by the sighting eye could reflect cognitive, rather than physiological factors. There have been suggestions that the inputs to the sighting eye seem to gain some priority in attention (Davson, 1949;Money, 1972;Porac & Coren, 1977;Sampson & Spong, 1962), and some reports suggest that higher level processing may be a factor in the disappearance of stabilized retinal images (Coren & Porac, 1974).…”

“…For example, Wade (1976) has reported that the interocular transfer of motion aftereffects is greater when the dominant eye has been adapted, while Mikaelian and Philips (Note 2) have found similar effects for the McCulloch orientation-specific color aftereffect. Porac and Coren (1977) have noted similar asymmetrical interocular transfer for more complex perceptual effects, such as illusion decrement. Thus, the pattern of results suggests that monocular asymmetries related to eye dominance are probably central in nature, occurring at a relatively high level in the visual system.…”