Sutton, J. E., & Roberts, W. A. (2002).
Failure to find evidence of stimulus generalization within pictorial categories in pigeons.
Journal of the Experimental Analysis of Behavior,
78, 333-343.
Pigeons' key pecks were reinforced in the presence of pictures
from one of two categories, cats or cars. A single picture
associated with reinforcement was used in Experiment 1, and 20
pictures from the same category were associated with
reinforcement in Experiment 2. Pigeons then were presented with
novel test pictures from the training category and from the
other, previously unseen, category. During Session 1 of testing,
pigeons pecked no more often at pictures from the reinforced
category than at pictures from the previously unseen category.
When pigeons were trained with pictures associated with
reinforcement or its absence from different categories in
Experiment 3, differential responding to novel pictures from
different categories appeared during Session 1. These findings
argue against a process of automatic stimulus generalization
within natural categories and in favor of the position that
category distinctions are not made until members of at least two
categories are compared with one another.
Key words: concepts, categories, stimulus generalization,
discrimination, pictures, pigeons