Ward, R.D. & Odum, A.L. (2008).
Sensitivity of conditional-discrimination performance to within-session variation of reinforcer frequency.
Journal of the Experimental Analysis of Behavior, 90, 301-311.
The present experiment developed a methodology for assessing
sensitivity of conditional-discrimination performance to
within-session variation of reinforcer frequency. Four
pigeons responded under a multiple schedule of
matching-to-sample components in which the ratio of
reinforcers for correct S1 and S2 responses was varied
across components within session. Initially, five components,
each arranging a different reinforcer-frequency ratio
(from 1:9 to 9:1), were presented randomly within a session.
Under this condition, sensitivity to reinforcer frequency
was low. Sensitivity failed to improve after extended exposure
to this condition, and under a condition in which only three
reinforcer-frequency ratios were varied within session. In a
later condition, three reinforcer-frequency ratios were varied
within session, but the reinforcer-frequency ratio in effect
was differentially signaled within each component. Under this
condition, values of sensitivity were similar to those
traditionally obtained when reinforcer-frequency ratios for
correct responses are varied across conditions. The
effects of signaled vs. unsignaled reinforcer-frequency
ratios were replicated in two subsequent conditions. The
present procedure could provide a practical alternative to
parametric variation of reinforcer frequency across
conditions and may be useful in characterizing the effects
of a variety of manipulations on steady-state sensitivity
to reinforcer frequency.
Key words: conditional discrimination, sensitivity, within-session
variation of reinforcer frequency, signaled reinforcer-frequency
ratios, choice, key peck, pigeon