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 three-component 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")[superscript k] or 2"Tt"/("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 2"Tt"/("Tt" + "Ti") and to a lesser extent as ("Tt/Ti")[superscript 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. (Contains 5 tables, 10 figures and 2 footnotes.)