Exteroceptive control of response under delayed reinforcement

Three white rats, after 50 continuous reinforcements, were exposed successively, under dim illumination, to reinforcement delays of 1, 3, 5, 7.5, 10, 15, and 20 sec, with prolonged training at the 20-sec level. Behavior was maintained at each level, and an increase in interval was accompanied by an increase in post-reinforcement pause. Subsequently, under both 20- and 30-sec delays, the animals were tested during half of each daily session to determine the effect of introducing darkness during each delay interval. The result of this stimulus “support” was to regularize and increase response rate for each animal at both interval values.     

Stimulus control of avoidance behavior

The introduction of a warning signal preceding shocks greatly increased the effectiveness of avoidance responding. Periods of “warm-up” at the beginning of the session were eliminated, and the number of shocks received by the subjects was greatly reduced. With response-shock interval constant, response rate increased as the interval between the response and the onset of the warning signal was shortened. The response tended to occur shortly after the onset of the warning signal regardless of the duration of these “safe” periods. A greatly elevated response rate was maintained even when the duration of the safe period was reduced to 0.3 sec. Thus, the pre-shock signal obtained nearly exclusive control of the responding and overrode the usual “temporal discrimination” of the response-shock interval.     

Stimulus generalization and the response-reinforcement contingency

Generalization gradients along a line-tilt continuum were obtained from groups of pigeons that had been trained to peck a key on different schedules of reinforcement. In Exp. I, gradients following training on a differential-reinforcement-of-low-rate (DRL) schedule proved to be much flatter than gradients following the usual 1-min variable interval (VI) training. In Exp. II, the value of the VI schedule itself was parametrically studied; Ss trained on long VI schedules (e.g., 4-min) produced much flatter gradients than Ss trained on short VI schedules (30-sec; 1-min). The results were interpreted mainly in terms of the relative control exerted by internal, proprioceptive cues on the different reinforcement schedules. Several implications of the results for other problems in the field of stimulus generalization are discussed.     

Some notes on time out from reinforcement

Pigeons produced food on a fixed-ratio schedule by pecking at one key, and an S^Δ period by pecking at a second (switching) key. Switching behavior was examined as a function of (a) size of the fixed ratio, (b) whether the S^Δ was of fixed duration or could be determined by the bird, (c) the introduction of a novel food S^D, (d) extinction of food responding, and (e) the stimuli associated with the S^D and S^Δ conditions. No monotonic relationship was obtained between ratio size and switching behavior. Switching behavior was, however, influenced by many variables. The results suggest that an interpretation of switching behavior in terms of its being reinforced by the removal of aversive conditions, is open to considerable question.     

Behavior stability and response rate as functions of reinforcement probability on “random ratio” schedules,

A random ratio schedule is one under which every ordinally specified response has the same probability of reinforcement as any other. Data have been gathered at several values of this type of schedule, using a separate group of pigeons for each schedule value and giving prolonged exposure to each value. No simple relationship was found between response rate and reinforcement probability. In general aspect group data from the present experiment agree with those from a single organism study cited. It was shown that 40 to 50 days of exposure to random ratio schedules yields fairly asymptotic response rate data. The tabulated raw data, and the results of some statistical manipulations, have been deposited with the American Documentation Institute.     

Pain-aggression toward inanimate objects

Attack behavior was elicited from squirrel monkeys by externally applied electric shock. The shock elicited attack toward other monkeys, rats, and mice, as well as toward inanimate objects, such as a stuffed doll, and even a round ball. A method of quantifying the attack behavior was devised on the basis of the attack against inanimate objects. This method revealed that the duration and probability of attack was a direct function of the shock intensity.     

Effect of CER on DRL responding

The effect of CER on DRL 16 was studied in four rats. All Ss showed complete CER suppression after five CER trials, together with some unconditioned post-shock suppression. This post-shock suppression showed complete recovery in all Ss after 10 days of five CER trials per day, but complete CER suppression continued throughout.     

Inducing behaviour change in adolescent delinquents

Approximately forty delinquents were offered part-time jobs of talking into a tape recorder about anything they wished. A simple reinforcement procedure was initiated whereby attendance at work became dependable and prompt within twenty-five meetings. A three-year follow-up of the first twenty employees showed a significant reduction in the frequency and severity of crime when compared to a matched-pair control group. The use of referral and “treatment” procedures was minimal.     

Quantitative relations between avoidance behavior and pituitary-adrenal cortical activity

The rate at which monkeys pressed a lever and avoided shocks was manipulated in several ways. Measurements were also made of their plasma levels of 17-hydroxycorticosteroids. The rate at which the animals pressed the lever and the frequency with which they received shocks were both implicated as determiners of the steroid levels.