Visual Half-Field Symmetry in Orientation Perception

Abstract

The perception of orientation in the left and right visual half-fields has been investigated. No evidence for interfield differences was obtained for the discrimination of single lines by line matching or in magnitude of the systematic orientation distortion in orientation contrast and rod-and-frame experiments. Furthermore, increasing the time interval between test and comparison lines in successive matching provides no evidence for a differential operation of short-term spatial memory in the two hemispheres. It is concluded that hemispheric asymmetries do not arise at the level of sensory processing of spatial signals.

On the use of discrimination to assess memory

“…In these tests a subject is asked to compare two stimuli that are separated by some amount of time. The general result of this research has been that the amount of time separating these two stimuli has little or no effect on the discrimination threshold (Bennett & Cortese, 1996;Blake, Cepeda, & Hiris, 1997;Greenlee, Rischewski, Mergner, & Seeger, 1993;Lee & Harris, 1996;Magnussen & Dyrnes, 1994;Magnussen & Greenlee, 1992;Magnussen, Greenlee, Asplund, & Dyrnes, 1990, 1991Magnussen, Greenlee, & Thomas, 1996;Magnussen, Idås, & Myhre, 1998;Magnussen, Landrø, & Johnsen, 1985;Nilson & Nelson, 1981;Regan, 1985;Vogels & Orban, 1986). These findings have been taken as evidence for very good or even "perfect" memory (Magnussen, 2000;Magnussen & Greenlee, 1999;Reinvang, Magnussen, Greenlee, & Larsson, 1998).…”

Representation of orientation and spatial frequency in perception and memory: A choice reaction-time analysis.

“…memory for orientation, as measured by delayed discrimination (Magnussen et al, 1985;Raney & Harvey, 1994;Vogels & Orban, 1986). Figure 3a, which plots accuracy as a function of ISI averaged across observers and spatial frequency difference conditions, indicates a similar small impairment of performance, which dropped from 77% to 71 % correct responses.…”

The psychophysics of perceptual memory

“…Experiments on the memory for the orientation of single lines or gratings show that retention is very good, but that there might be a slight decay of information in short-term memory (Magnussen, Landrù, & Johnsen, 1985;Vogels & Orban, 1986;Raney & Harvey, 1994). In a recent study where memory for grating orientation was measured by a``same-dierent'' judgment task with a wide range of reference orientations and spatial frequencies pooled in a single experimental run, correct judgments dropped six percentage points across a 10-s ISI .…”