Squirrel Monkeys, Discrimination Learning and Sequential Testing: The Redundancy, Relative Position and Complexity of Random Shapes

This study was a partial replication of one previously
reported by Nash and Michels (1966). The purpose was to investigate
perceptual form discrimination behavior of young
squirrel monkeys as affected by contextual variables of the
stimulus. The variables examined were Redundancy, Position
and, of the form itself, Complexity. In addition, a sequential
method of testing and recording was compared with
the conventional 50-trial block procedure. Two 17 month old monkeys were tested on eight twochoice
problems in a Purdue General Test Apparatus. The
problems each consisted of two slides on which pairs of
random shapes were presented. The shapes within each pair
of slides were held constant on the parameters investigated.
One slide was designated as the positive stimulus and presented
in either the right or left position in random order. The number of correct responses for the 50-trial
blocks, as examined by an analysis of variance, failed to
reach statistical significance for any of the variables
investigated. However, graphic inspection of the data
suggests general agreement with the findings of Nash and
Michels (1966). In comparing the two methods of testing,
the sequential test of performance (STOP) was equally as
effective as the conventional method and could have provided
a substantial savings in test time. Comparison of
scores obtained by the two procedures shows good correlation. Although no strong conclusions can be drawn from the
data, they do lead to the speculation that there is a relationship
between effect and extent of redundancy, and
that failure of S to make a correct response in the test
situation may be the result of cue sampling rather than a
failure to discriminate.