Ta, W.-M., Pitts, R.C., Hughes, C.E., McLean, A.P. & Grace, R.C. (2008).
Rapid acquisition of preference in concurrent chains: effects of d-amphetamine on sensitivity to reinforcement delay.
Journal of the Experimental Analysis of Behavior, 89, 71-91.
The purpose of this study was to examine effects of d-amphetamine on choice controlled by reinforcement delay.
Eight pigeons responded under a concurrent-chains procedure in which one terminal-link schedule was always fixed-
interval 8 s, and the other terminal-link schedule changed from session to session between fixed-interval 4 s and
fixed-interval 16 s according to a 31-step pseudorandom binary sequence. After sufficient exposure to these
contingencies (at least once through the pseudorandom binary sequence), the pigeons acquired a preference for
the shorter reinforcement delay within each session. Estimates of the sensitivity to reinforcement immediacy
were similar to those obtained in previous studies. For all pigeons, at least one dose of d-amphetamine
attenuated preference and, hence, decreased estimates of sensitivity to reinforcement immediacy; in most cases,
this effect occurred without a change in overall response rates. In many cases, the reduced sensitivity to
reinforcement delay produced by d-amphetamine resulted primarily from a decrease in the asymptotic level of
preference achieved within the session; in some cases, d-amphetamine produced complete indifference. These
findings suggest that a reduction in the sensitivity to reinforcement delay may be an important behavioral
mechanism of the effects of psychomotor stimulants.
Key words: preference, reinforcement delay, acquisition, behavioral mechanisms, d-amphetamine, key peck, pigeons