Two- versus three-alternative concurrent-chain schedules: a test of three models.
Two experiments with pigeons used concurrent-chain procedures with variable-interval schedules as initial links and different delays to food as terminal links. Two schedules were present in all sessions, but a 3rd schedule was alternately present and absent in successive sessions. When the 3rd schedule delivered food with no terminal-link delay, the presence of this schedule led to an increase in preference for the schedule with the shorter terminal link of the 2 unchanged schedules. When the terminal-link delay for the 3rd schedule was 30 s, the presence of this schedule led to a decrease in preference for the schedule with the shorter terminal link of the 2 unchanged schedules. These results are inconsistent with the predictions of R. Grace's (1994) contextual-choice model, but they are consistent with 2 other mathematical models--delay-reduction theory and the hyperbolic value-added model.
Psychology Department, Southern Connecticut State University, New Haven 06515-1355, USA. mazur@southernct.edu
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D000704:Analysis of Variance; D000818:Animals; D002755:Choice Behavior; D010856:Columbidae; D003216:Conditioning, Operant; D008960:Models, Psychological