Aggression as a reinforcer: operant behavior in the mouse-killing rat

Two experiments examined mouse killing as a reinforcer of key pressing by rats that killed mice. In Experiment I, mouse-killing rats performed the key-pressing response when each press was reinforced with presentation of a mouse. Offered a choice between a key that yielded presentation of mice and one that did not, the rats preferred the key that yielded mice. When the contingency was reversed, the rats preferred the other key and continued to kill mice. In Experiment II, mouse-killing rats that did not kill rat pups performed a key-pressing response reinforced with presentation of mice on a variable-interval schedule. In tests for responding reinforced on that schedule with presentation of normal mice, anesthetized mice, dead mice, or rat pups, these rats that killed mice but not rat pups exhibited a decline in response rate when rat pups were the reinforcer. Altering the condition of the mice did not significantly affect performance.     

A yoked-chamber comparison of concurrent and multiple schedules

Pigeons were exposed to alternative pairs of variable-interval schedules correlated with red and green lights on one key (the food key). In one experimental chamber, responses on a white key (the changeover key) changed the color of the food key and initiated a 2-sec changeover delay. Pigeons in a second chamber obtained food by pecking on a colored key whenever the pigeons in the first (concurrent) chamber had obtained food for a peck on that key color. There was no changeover key in the second (multiple) chamber: changeover responses in the first chamber alternated the schedules and colors in both chambers. The pigeons in both chambers emitted the same proportion of responses on each of the variable-interval schedules, and mastered discrimination reversals at the same rate. The pigeons differed only in their absolute response rates, which were greater under the concurrent schedules. In a second experiment, changes in key color occurred automatically, with different proportions of time allocated to the two variable-interval schedules. Matching of relative response frequency to relative reinforcement frequency was affected by the relative amounts of time in each component, by rate of changeovers, and by manipulations of the variable-interval scheduling.     

Infantile handling and sex as determinants of the negative reinforcing effects of gentling

Summary BD IX rats were trained to avoid a black and white compartment which was associated with gentling. The rats were given 12 acquisition sessions in which they were stroked if they remained in the critical compartment at the end of the fifteen 20-sec intervals during the 5-min test period. The results indicated that the negative reinforcing effects of gentling were a function of the early handling history and sex of the rat.This research was aided by Grant APA-247 from the National Research Council of Canada. The author thanks David Wood for his active collaboration in conducting the experiment.     

Detailed recording of spontaneous rapid events

The Rockefeller University, New York, New York 10021 Events such as barpresses or licks, which may occur at any time during the day, are often clustered into bouts. The internal structure of such bouts can be recorded using an AM tape recorder, running the tape recorder only while bouts are in progress, and can later be analyzed off-line on a digital computer.     

Pause measures during reading and recall in serial list learning

An investigation is reported into pausing and grouping during the serial learning of letter strings, when presented randomly by length and when presented in ascending order. Mean pause times for the reading and recall of longer lists were significantly greater than for lists of shorter span due to extended pausing at specific list positions. In general, reading rhythms were duplicated during recall. Subjects were highly consistent in maintaining their level of pause duration across lists and responded to additions in list length by increasing their number of groups, not by increasing group size. Triadic sequences were the most popular form of spontaneous organization. Pausing measures are discussed as indices of organizational strategies.