Two auditory stimuli, separated by a fixed intertrial interval, were alternately presented to two rats in a closed environment. The positive conditioned stimulus (CS+) terminated with the offset of a 2-mA, 0.75-sec shock. The negative conditioned stimulus (CS-) terminated without shock. The incidence of the "stereotyped fighting posture" was recorded during the CS+, the CS-, the intertrial interval, and shock. The results showed an increase in the percentage of conditioned responses during the CS+, and a decrease during both the CS- and the intertrial interval, when the duration of the conditioned stimuli and the intertrial interval was 16 sec. Appropriate changes in the incidence of aggression during the two stimuli were obtained following the reversal of the stimulus functions. During the acquisition and reversal phases there was a between-session decrement and a within-session improvement in the incidence of aggression during the CS+, defined as warm-up. The presentation of free shocks before the conditioning sessions was effective in reducing the warm-up only when the interval between shocks was 64 sec. These data were interpreted as demonstrating classical conditioning of shock-elicited aggression, with little chance of non-associative factors contributing to the measurement of the conditioned response.

ONE OF THE MAJOR SYMPTOMS of the learning disability syndrome is short attention span and distractibility. Several investigators have recently described the phenomena and-depending upon their area of specialization-have provided various labels such as hyperactivity, hyperkinesis, distractibility, -and short attention span.' While the behavioral components of distractibility have been amply described, the experimental investigation of it in children with learning disabilities is limited. R. A. Dykman and his associates treated attention as a unitary trait consisting of alertness, stimulus selection, focusing, and vigilance.' These investigators developed a motor impulsivity task and reported that children with learning disabilities had a higher error rate and longer response time than normal control subjects.

Hyperactive and hypoactive children show attentional deficits. An effort was made to modify their approaches to a vigilance task by varying the feedback received for correct detections and false alarms. It was expected that hyperactive children would do better when receiving knowledge of false alarms; hypoactive children would do better when receiving knowledge of correct responses. 20 hyperactive and 20 hypoactive children, aged 6 to 10 yr., were each tested under three conditions with a vigilance task: (a) feedback for correct responses (KR+), (b) feedback for false alarms (KR-), (c) no feedback NKR). Feedback was given by a tone. For the total error score, hyperactive subjects committed more errors than hypoactive ones under KR+ and fewer errors under KR-. Hypoactive children committed fewer errors under KR+ than no knowledge. Partial support for the hypothesis was obtained. Hyperactive children generally to better when given knowledge of errors; they become more cautious in responding. Hypoactive children do best when given information regarding correct responses; they become less inhibited in responding.

Hyperactive and hypoactive children show attentional deficits. An effort was made to modify their approaches to a vigilance task by varying the feedback received for correct detections and false alarms. It was expected that hyperactive children would do better when receiving knowledge of false alarms; hypoactive children would do better when receiving knowledge of correct responses. 20 hyperactive and 20 hypoactive children, ages 6 to 10 yr., were each tested under three conditions with a vigilance task: (a) feedback for correct responses (KR+), (b) feedback for false alarms (KR -), (c) no feedback (NKR). Feedback was given by a tone. For the total error score, hyperactive subjects committed more errors than hypoactive ones under KR+ and fewer errors under KR -. Hypoactive children committed fewer errors under KR+ than no knowledge. Partial support for the hypothesis was obtained. Hyperactive children generally do better when given knowledge of errors; they become more cautious in responding. Hypoactive children do best when given information regarding correct responses; they become less inhibited in responding.