Peña, T., Pitts, R. C., & Galizio, M. (2006).
Identity matching-to-sample with olfactory stimuli in rats.
Journal of the Experimental Analysis of Behavior, 85, 203-
221.
Identity matching-to-sample has been difficult to demonstrate in rats,
but most studies have used visual stimuli. There is evidence that rats
can acquire complex forms of olfactory stimulus control, and the present
study explored the possibility that identity matching might be facilitated
in rats if olfactory stimuli were used. Four rats were trained on an
identity match-to-sample procedure with odorants mixed in cups of sand
as stimuli. Digging in the sample cup produced two comparison cups, and
digging in the comparison cup that contained the same scent as the sample
was reinforced. When criterion accuracy levels were reached, novel stimuli
were added to the baseline training regimen. All 4 rats reached terminal
performance of above 90% correct matching with more than 20 different baseline
stimuli and matched novel stimulus combinations with above-chance accuracy; 3
of the 4 rats matched novel stimuli at levels significantly above chance.
Accurate matching performance was demonstrated both with 2- and 3-comparison
procedures. These results suggest that generalized matching-to-sample can be
observed in rats when olfactory stimuli are used and, furthermore, that
multiple-exemplar training may be important for its emergence.
Key words: matching-to-sample, concept learning, discrimination, olfactory learning,
stimulus control, digging, rat