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Three White King pigeons were exposed to fixed-time schedules ranging from 60 to 240 sec. General activity and attack against a conspecific target were measured separately at each interreinforcer interval value. Comparison of the temporal distributions of activity and attack revealed significant differences in their temporal locus and overall distribution between reinforcer presentations. At all interval values, attack was localized to the postreinforcer period, and peaked at the same absolute time (5–10 sec) following each reinforcer presentation. General activity was more uniformly distributed between reinforcers, and the peak level occurred later in the interval. As the interval length increased, peak levels of activity shifted to later times following reinforcement. These differences question traditional accounts which posit a unitary process underlying induced behaviors, while supporting Cohen, Looney, Campagnoni and Lawler's recent two-state model of induced behaviors [8].

Schedule-induced polydipsia as a function of six water dipper sizes was examined in four food-deprived rats under Fixed Time 1- and 2-minute schedules. Increasing dipper size increased session water intake but did not affect the number of intervals containing at least one barpress (i.e., number of bouts), nor the number of barpresses per bout, nor the temporal distribution of barpressing within the interfood interval. Previous research showing polydipsic intake to be impervious to other types of restrictions on water availability have suggested the notion of a volume constancy mechanism. The present research raises questions about the operation of the volume constancy mechanism, questions about how to conceptualize the dipper size manipulation, and questions about variables which affect the temporal locus of drinking.