M. Dill et M. Fahle, Display symmetry affects positional specificity in same-different judgmentof pairs of novel visual patterns, VISION RES, 39(22), 1999, pp. 3752-3760
Deciding whether a novel visual pattern is the same as or different from a
previously seen reference is easier if both stimuli are presented to the sa
me rather than to different locations in the field of view (Foster & Kahn (
1985). Biological Cybernetics, 51, 305-312; Dill & Fable (1998). Perception
and Psychophysics, 60, 65-81). We investigated whether pattern symmetry in
teracts with the effect of translation. Patterns were small dot-clouds whic
h could be mirror-symmetric or asymmetric. Translations were displacements
of the visual pattern symmetrically across the fovea, either left-right or
above-below. We found that same-different discriminations were worse (less
accurate and slower) for translated patterns, to an extent which in general
was not influenced by pattern symmetry, or pattern orientation, or directi
on of displacement. However, if the displaced pattern was a mirror image of
the original one (along the trajectory of the displacement), then performa
nce was largely invariant to translation. Both positional specificity and i
ts reduction in symmetric displays may be explained by location-specific pr
e-processing of the visual input. (C) 1999 Elsevier Science Ltd. All rights
reserved.