Avoidance and escape latencies were examined in 24 rats trained in two-way avoidance response to auditory and visual conditioned stimuli (CS). In rats trained with darkness CS the escape latencies decreased within the first 50-trial session but later were stable over the course of nine sessions. Avoidance latencies shortened within sessions as the response-eliciting properties of the conditioned stimuli increased. On the contrary, median daily avoidance latencies lengthened during training. Training with the more salient auditory stimulus resulted in a decrease in the probability of avoidance responses early in the CS-US interval, reflecting the development of inhibition of delay. Acquired inhibition of delay was eliminated by an increase in the fear-inducing properties of situational cues. When presented in a compound, the less salient darkness stimulus was fully overshadowed by the noise stimulus.

/pdf/latency-of-the-two-way-avoidance-response-in-rats-inhibition-4fvqinyovp.pdf

Latency of the two-way avoidance response in rats: inhibition of delay.

Two rhesus monkeys were trained as operators in a compensatory manual control system similar to systems used in human studies. Training procedures used to shape compensatory tracking behavior included a multiple shock-avoidance technique, the gradual introduction of the system input, and sharpening visual stimulus control of tracking behavior. Time-on-target scores for the monkeys were 95% to 98% while responding to three different frequency bandwidths of the system input. As frequency bandwidth increased, no significant increase in error was noted, the monkeys returned the target element to the center target area at increasing rates, and the number of shocks delivered to each subject remained low. Bode plots and stripouts of input, output, and error signals resembled those typically obtained in human studies. Through extrapolations based on nonhuman primate performance, the conclusion was that the task development and training procedures of the present study provided a means for estimating human performance in manual control systems under environmental stress or in hazardous environments. Language: en

Training and performance of rhesus monkeys as operators in a compensatory manual control system.

Rats received discrimination training where light-on was the S+ condition and light-off the S- condition. 2 Ss were trained with a fixed interval (FI) 30-sec. schedule with a limited hold of 5 sec. during S+, while 3 Ss were trained with a variable interval (VI) 30-sec. schedule during S+. Probe testing produced steeper generalization gradients for the FI trained Ss than for the VI trained Ss. Exp. 2 was conducted with 2 more VI Ss trained and tested in an identical manner to the FI Ss of Exp. 1. Gradients for the FI Ss of Exp. 1 were steeper than for those of the VI Ss of Exp. 2. Thus less stimulus control was exerted after training with VI than with FI schedules. The discriminative properties of reinforcement during the VI schedule competed with and thereby weakened S+ stimulus control. An alternate explanation in terms of changes in response patterns was discussed.

Stimulus Control After Training with Fixed Interval and Variable Interval Schedules of Reinforcement

Rats in a shuttle box were reinforced by shock termination on 60 training trials. On the day following the end of training, 30 massed extinction trials were given on which shock termination was delayed for 20 sec following the shuttling response. To test for spontaneous recovery, five additional extinction trials were given after recovery intervals of 5 min, 15 min, 60 min, or 24 h. The results showed spontaneous recovery to be a negatively accelerated monotonic function of the recovery interval. Only a very slight increase in spontaneous recovery was observed when the recovery interval was increased from 60 min to 24 h.

/pdf/spontaneous-recovery-of-an-escape-response-31lwjd5ej3.pdf

Spontaneous recovery of an escape response

Operant responding for water reinforcement was investigated in three New Zealand albino rabbits. Performance of two rabbits under FR3, FR8t and FR95 schedules was similar to the performance of other organisms exposed to low- or high-value fixed-ratio reinforcement. The behavior of the third rabbit under an FI 1-min LH 5-sec schedule was characteristic of fixed-ratio performance. These data were compared with data obtained from other organisms.

/pdf/schedule-control-in-the-rabbit-44cyxm9ukv.pdf

Theodore J. Newsom

Papers

Stimulus Control After Training with Fixed Interval and Variable Interval Schedules of Reinforcement

Spontaneous recovery of an escape response

Schedule control in the rabbit