61 research outputs found
Recent advances in cortical visual impairment
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66022/1/j.1469-8749.2001.tb00387.x.pd
Configurational asymmetry in vernier offset detection
Two psychophysical experiments were conducted at the horizontal and vertical
orientations respectively, demonstrating substantial main effect of
configuration, but no effect of offset direction on vernier acuity. In
Experiment 1, a pair of horizontal bars were arranged side by side with a large
gap between them. The observers were, on average, significantly better at
discriminating a vertical offset if the right-hand bar was below the left-hand
bar than vice versa, regardless of which bar they experienced as displaced and
which as constant. A similar asymmetry was evident in Experiment 2 where
observers judged horizontal offset for a pair of vertically oriented bars, where
one was placed above the other. In this case average performance was better if
the upper bar was on the right of the lower bar rather than on its left. There
were large individual variations in the asymmetrical trend, but the effect could
not be explained by subjective response bias. Furthermore, vernier acuity
improved significantly and the asymmetry decreased more or less as a function of
training. The average asymmetrical trend was consistent across training days and
across two orientations, which indicates that the processing of line vernier
stimuli is possibly configuration-specific in the cardinal orientation
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