Effects of Brief-Signal Number and Location on Responding Maintained by Delay of Reinforcement

The purpose of the present series of experiments was to examine the effects of the number, type, and location of brief signal(s) occurring during, but not throughout, a delay period, on responding maintained by the delay of reinforcement. In each experiment, a tandem variable time (VT) 60-s fixed interval (FI) 9-s schedule was used as a baseline condition of an immediate reinforcement against which delay conditions were examined. For the delay conditions, a chained variable interval (VI) 60-s fixed time (FT) 9-s (delay period) schedule was used, and the imposition of the brief signal (blackout) during the delay period was manipulated. In Experiment 1, when a brief signal(s) was imposed at the fixed temporal location during the delay period, the VI component response rate was maintained at a comparable level to the baseline. Conversely, when a brief signal was imposed at the variable temporal locations during the delay period, the VI component response rate diminished to low levels compared to the baseline. In Experiment 2, when a brief signal was imposed at the beginning of the delay period, the VI response rate was maintained at a higher level compared to when the brief signal was imposed at the middle or end of the delay period. In both Experiment 1 and 2, when the brief signal was contingent and temporally contiguous with the required response (a keypeck that completed the VI component and started the delay period), the VI response rate was maintained at a higher level compared to when there was a disruption in temporal contiguity between the required response and brief signal presentation. To examine this observation, in Experiment 3, a brief signal was imposed at the variable temporal location during the delay period, however, a contingency was imposed where an additional response after the elapse of the signal timer was required to produce the brief signal. In this procedure, the VI response rate was maintained at a higher level compared to when the brief signal was presented at the variable temporal location without an additional response requirement for the brief signal presentation. These results underline the importance of response-brief signal contingency and temporal contiguity in maintaining responding by partially signaled delay of reinforcement