Iversen, I. H. (1997).
Matching-to-sample performance in rats: A case of mistaken identity?
Journal of the Experimental Analysis of Behavior,
68, 27-45.
Three rats had previously acquired a simultaneous
matching-to-sample performance with steady and blinking lights.
In training, the sample stimulus had always appeared on the
middle of three horizontally arranged keys with the comparison
stimuli on the side keys. In Experiment 1, the sample stimulus
appeared on any of the three keys with the comparison stimuli on
the remaining two. The matching-to-sample performance broke down
with variable sample and comparison locations; the sample
stimulus did not control responding to the comparison stimuli
when it appeared on a side key, but it retained control when it
appeared on the middle key (as in training). In Experiment 2, the
rats were trained with the sample always on the left key. When
the sample appeared on either of the trained locations (left or
middle key), it retained control for both locations. When the
sample then appeared on any of the three keys, as in Experiment
1, sample control did not transfer to the untrained location
(right key). The experiments demonstrate that training with fixed
sample and comparison locations may establish spatial location as
an additional controlling aspect of the stimuli displayed on the
keys; stimulus location had become part of the definition of the
controlling stimuli. The rats' performance seemed best described
as specific discriminations involving the visual stimuli and
their spatial locations rather than as identity matching.
Key words: identity matching, sample location, reflexivity,
symmetry, mistaken identity, nose key, rats