Journal of the experimental analysis of behavior
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Four Asian quail (Coturnix coturnix japonica) were exposed to concurrent-chain schedules, the terminal links of which were either variable-interval 30 sec and variable-time 30 sec, or fixed-interval 30 sec and fixed-time 30 sec. Except for one bird that exhibited a preference for the variable-interval schedule over the variable-time schedule, no consistent preferences were demonstrated for response-dependent or response-independent schedules. ⋯ The discrimination between terminal-link schedules was rapidly recovered after the schedule positions were reversed. Casual observations revealed that the birds engaged in stereotypic circling and pecking while the response-independent schedules were operative.