JOURNAL OF THE EXPERIMENTAL ANALYSIS OF BEHAVIOR 2004, 81, 215–237 NUMBER 3(MAY) TEMPORAL CONTEXT IN CONCURRENT CHAINS: I. TERMINAL-LINK DURATION

Two experiments are reported in which the ratio of the average times spent in the terminal and initial links (Tt/Ti) in concurrent chains was varied. In Experiment 1, pigeons responded in a threecomponent procedure in which terminal-link variable-interval schedules were in constant ratio, but their average duration increased across components by a factor of two. The log initial-link response ratio was a negatively accelerated function of Tt/Ti. Overall, the data were well described by Grace’s (1994) contextual choice model (CCM) with temporal context represented as (Tt/Ti) k or 2Tt/(Tt � Ti), and by Mazur’s (2001) hyperbolic value-added model (HVA), with each model accounting for approximately 93 % of the variance. In Experiment 2, fixed-parameter predictions for each model were generated, based on the data from Experiment 1, for conditions in which Tt/Ti was varied over a more extreme range. Data were consistent with the predictions of CCM with temporal context represented as 2Tt/(Tt � Ti) and to a lesser extent as (Tt/Ti) k, but not with HVA. Overall, these results suggest that preference increases as a hyperbolic function of Tt/Ti when terminal-link duration is increased relative to initial-link duration, with the terminal-link schedule ratio held constant. Key words: choice, concurrent chains, terminal-link duration, reinforcement context, contextual choice model, hyperbolic value added model, key peck, pigeon