Author:  Fumio Kanbe

Title: Can the comparisons of feature locations explain the difficulty in
discriminating mirror-reflected pairs of geometrical figures from
disoriented identical pairs?

Journal: Symmetry 2015, 7, 89-104 (Online version)

doi: 10.3390/sym7010089

Abstract: The present experiment investigates whether patterns of shifts of
feature locations could affect the same/different decisions of
simultaneously presented pairs of geometrical figures. A shift of locations
was defined as the angular distance from the location of a feature in one
figure to the location of the same feature in another figure.  It was
hypothesized that the difficulty in discriminating mirror-reflected (or
axisymmetric) pairs from disoriented identical pairs was caused by complex
shifting patterns inherent in axisymmetric pairs. According to the shifts of
the locations of the four structural features, five pair types were
prepared.  They could be ordered from completely identical to completely
different in their shifts: identical 0/4 pairs, non-identical 1/4 pairs,
non-identical 2/4 pairs = axisymmetric 2/4 pairs and non-identical 4/4
pairs. The latencies for non-identical pairs decreased with the increase of
difference in the shifts of feature locations, indicating that serial,
self-terminating comparisons of the shifts were applied to the
discrimination of non-identical pairs from identical pairs. However, the
longer latencies in axisymmetric 2/4 pairs than in non-identical 2/4 pairs
suggested that the difficulty for axisymmetric pairs was not caused by the
complex shifting patterns, and the difficulty was not satisfactorily
explained by the comparisons of feature locations.

Keywords:  same/different decision; axisymmetry; graph invariant; shifts of
feature locations; mental rotation