Cook, R. G. (2002).
The structure of pigeon multiple-class same–different learning.
Journal of the Experimental Analysis of Behavior,
78, 345-364.
Three experiments examined the structure of the decision
framework used by pigeons in learning a multiple-class
same–different task. Using a same–different choice
task requiring the discrimination of odd-item different displays
(one or more of the display's component elements differed) from
same displays (all display components identical), pigeons were
concurrently trained with sets of four discriminable display
types. In each experiment, the consistent group was tested such
that the same and different displays of four display types were
consistently mapped onto their choice alternatives. The
inconsistent group received a conflicting mapping of the same and
different displays and the choice alternatives that differed
across the four display types but were consistent within a
display type. Experiment 1 tested experienced pigeons, and
Experiment 2 tested naive pigeons. In both experiments, the
consistent group learned their discrimination faster and to a
higher level of choice accuracy than did the inconsistent group,
which performed poorly in general. Only in the consistent group
was the discrimination transferred to novel stimuli, indicative
of concept formation in that group. A third experiment documented
that the different display classes were discriminable from one
another. These results suggest that pigeons attempt to generate a
single discriminative rule when learning this type of task, and
that this general rule can cover a large variety of stimulus
elements and organizations, consistent with previous evidence
suggesting that pigeons may be capable of learning relatively
unbounded relational same–different concepts.
Key words: same–different discrimination, concept learning,
stimulus relations, decision theory, pigeons