Jitsumori, M., Siemann, M., Lehr, M., & Delius, J. D. (2002).
A new approach to the formation of equivalence classes in pigeons.
Journal of the Experimental Analysis of Behavior,
78, 397-408.
Four pigeons were given simultaneous discrimination training with
visual patterns arbitrarily divided into two sets, with the
stimuli in one set designated A1, B1, C1, and D1 and those in the
other set designated A2, B2, C2, and D2. In sequentially
introduced training phases, the pigeons were exposed to a series
of reversals to establish AB and then CD equivalences. In
subsequent testing sessions, a subset of stimuli from one set
served as positive stimuli and those from the other set as
negative stimuli on training trials, and transfer of the
reinforced relation to other members of the sets was tested with
nonreinforced probe trials. The pigeons were trained further on
AC and BD equivalences and then were tested for the emergence of
untrained AD and BC equivalences. Two of the 4 pigeons exhibited
the emergence of one of these untrained equivalences, evidence
for the emergence of transitive relations. This finding suggests
that the pigeons established three-member functional equivalence
classes by incorporating separately trained multiple equivalence
relations. Repeated reversal training and probe testing enabled
us to explore the formation and expansion of functional
equivalence classes in pigeons.
Key words: stimulus equivalence, functional equivalence,
discrimination learning, generalization, categorization, conceptualization,
pigeons