Visual discrimination of shape by Humans. II: (I) matrix figures and (II) minimal area changes

Two experiments are described in which an attempt was made systematically to vary two dimensional shapes according to a pre-arranged design. In the first, subjects were presented tachistoscopically with pairs of “reflexive matrix figures” whose members were either horizontally or vertically orientated; and it was found that reaction times to horizontal pairs were faster than to vertical ones, a result that is in keeping with previous findings. In the second experiment two ensembles were devised that were alike in every respect save that one group was extended or reduced vertically while the other varied horizontally. Performance was better on the vertically orientated ensemble. These findings are briefly related to former studies and the pre-eminence of vertical symmetry is underlined.