Response latency as a function of reinforcement schedule

Four Ss were trained to press and hold down a telegraph key in the presence of a light. Subsequent release of the key during a tone was followed by water reinforcement. The schedule of reinforcement for key release was varied, and its effects on the latency (RT) of key release to the tone were studied. Both median RT and variability of RT were found to be inversely related to frequency of reinforcement as determined by the schedule.     

Response latency as a function of amount of reinforcement

Food-deprived rats were trained to press and hold down a telegraph key in the presence of a light. Subsequent release of the key during a tone was followed by 0.15 ml of a 20-percent sucrose solution as reinforcement. The Ss were subsequently shifted to a 0-percent and to a 5-percent solution from the 20-percent base line. The median RT and the variability of RT increased markedly as a result of the shift to the lower sucrose concentrations. For all Ss, the change in median and variability was greater for the shift to the 0-percent solution than for the shift to the 5-percent solution. It is probable that median RT and variability of RT are inversely related to amount of reinforcement.     

Fixed-time schedule effects as a function of baseline reinforcement rate

Using an arbitrary response, we evaluated fixed-time (FT) schedules that were either similar or dissimilar to a baseline (response-dependent) reinforcement schedule and extinction. Results suggested that both FT schedules and extinction resulted in decreased responding. However, FT schedules were more effective in reducing response rates if the FT reinforcer rate was dissimilar to baseline reinforcer rates. Possible reasons for this difference were evaluated with data analysis methods designed to identify adventitious response-reinforcer relations.     

Effects of reinforcement amount on attack induced under a fixed-interval schedule in pigeons

Key pecking by pigeons was maintained on a chained fixed-interval 4-min (12-min for 1 subject) fixed-ratio 1 schedule of food presentation. Attacks toward a restrained and protected conspecific were recorded. In the first experiment, the amount of food presented per interval was manipulated across phases by varying the number of fixed ratios required in the terminal link of the chain. Measures of attack for all pigeons during the fixed-interval component increased monotonically as a function of food amount. In the second experiment, two different food amounts alternated within each experimental session under a multiple schedule. For both pigeons in this experiment, measures of attack were higher during the component that delivered the larger food amount per interval. The differences in levels of attack induced by the two food amounts in Experiment 2, however, were not as great as in Experiment 1; apparently this was because attack during the first interval of each component was controlled in part (P-5626) or entirely (P-7848) by the reinforcement amount delivered at the end of the previous component. Attack was also a function of the location of the interfood interval within the session. For both pigeons, attack tended to decrease throughout the session. The results of both experiments suggest that attack is an increasing function of reinforcement amount under fixed-interval schedules, but that this function may be influenced by the manner in which reinforcement amount is manipulated, by the duration of the interfood interval, and by the location of the interfood interval within the experimental session. In general, these results are compatible with theories of induced attack and other schedule-induced behavior that emphasize aversive after-effects of reinforcement presentation.     

Response rate as a function of amount of reinforcement for a signalled concurrent response

Pigeons were exposed to two equal, concurrent variable-interval schedules of reinforcement on two response keys. One key was continuously illuminated. Pecking on that key produced reinforcements of constant duration. The other key was normally dark, except that availability of reinforcement was signalled by illuminating the key. The duration of access to a grain reinforcer was varied on the key that signalled reinforcement. Rate of response on the first key, the one that did not signal reinforcement, was found to vary inversely with duration of signalled reinforcement on the other key. The latency between the signal and the peck that produced signalled reinforcement remained about constant. These results show that responding on one key in concurrent variable-interval schedules depends on the reinforcement delivered by both schedules and is independent of responding on the other key.