Electric shock produced drinking in the squirrel monkey.

Squirrel monkeys were periodically exposed to brief electric tail shocks in a test environment containing a rubber hose, response lever, and a water spout. Shock delivery produced preshock lever pressing and postshock hose biting. Additionally, all subjects displayed licking responses following postshock biting-attack episodes. Further experiments showed that licking was: (1) influenced by hours of water deprivation; (2) drinking behavior; (3) the direct result of shock delivery; and (4) developed spontaneously in naive subjects with or without opportunities for hose biting or lever pressing. Removing the opportunity to attack increased postshock drinking. A noxious environmental stimulus that causes aggression can also produce drinking.     

AUGMENTING SIMPLIFIED HABIT REVERSAL IN THE TREATMENT OF ORAL-DIGITAL HABITS EXHIBITED BY INDIVIDUALS WITH MENTAL RETARDATION

We investigated whether a simplified habit reversal treatment eliminates fingernail biting and related oral-digital habits exhibited by individuals with mild to moderate mental retardation. Although simplified habit reversal did little to decrease the target behaviors for 3 of 4 participants, simplified habit reversal plus additional treatment procedures decreased the behavior to near-zero levels for all participants. These procedures included remote prompting, remote contingencies involving differential reinforcement plus response cost, and differential reinforcement of nail growth. Limitations of habit reversal for individuals with mental retardation along with directions for future research involving therapist-mediated treatment procedures, particularly those involving remote prompting and remote contingencies, are discussed.     

Body-Focused Repetitive Behaviors: The Proximal and Distal Effects of Affective Variables on Behavioral Expression

This paper reports on 2 studies designed to examine the contribution of affective variables on the expression of body-focused repetitive behaviors (BFRBs; e.g., skin picking, nail biting). The first study revealed that persons engaging in a BFRB experienced significantly higher levels of anxiety and depression than those without BFRBs. The second study was conducted to determine if repetitive behaviors were differentially affected across various emotional states and across those persons with and without BFRBs. Participants were randomly exposed to anxiety, depression, boredom, and control conditions. Results showed no differential effects on the occurrence of repetitive behaviors within the no-BFRB group; however, the BFRB group engaged in more repetitive behaviors in the Bored condition than in the Control condition. This study offers the first experimental evidence that emotional variables can have a differential impact on the expression of BFRBs.     

Target-biting behavior of individually and group-housed mice and rats

The effects of housing conditions (individual or grouped) on the biting of an inanimate target by confined male mice and rats were measured. It was observed that, for both mice and rats, individual housing markedly increased the number of target bites per session. These results indicate that the target-biting paradigm is sensitive to those factors responsible for the increase in fighting behavior following individual housing.     

Schedule-induced biting under fixed-interval schedules of food or electric-shock presentation

Squirrel monkeys pressed a lever under fixed-interval schedules of food or of electric-shock presentation. Both schedules induced repeated biting on a latex hose. Whether lever pressing was controlled by food or by electric shock, a pattern of decreasing hose biting and increasing lever pressing occurred within fixed-interval cycles. As the fixed-interval duration was increased from 6 to 600 sec, average rates of lever pressing decreased under both schedules. Average rates of hose biting first increased with increasing parameter value, reaching a maximum at values that varied from 60 to 337 sec in different monkeys, and then declined at higher values. d-Amphetamine at appropriate doses increased overall rates of lever pressing maintained by food or by shock, but either did not affect or decreased overall rates of hose biting. When no timeout period occurred between fixed-interval cycles, the monkeys bit most frequently immediately after food or electric shock was presented. When there was a timeout period, hose biting began shortly after the start of the fixed-interval cycles, with little or no hose biting immediately after food or electric shock was presented. Most hose biting appeared to be schedule-induced rather than food- or shock-induced.     

Brief exposure to contingent reinforcement produces a sustained increment in the strength of an elicited response.

Squirrel monkeys' lever pressing produced by response-independent shock was measured before, and for an extended period following, exposure to a shock-avoidance procedure. Following avoidance training, the frequency of responding increased by multiples of 10 to 50 across subjects and evidence little or no decrement for up to 6 months of postreinforcement testing. Manual responding produced by intense environmental stimulation may be substantially strengthened by a brief history of reinforcement, such that it is sustained over long periods without reinforcement.     

SOME RELATIONS BETWEEN CLASSICALLY CONDITIONED AGGRESSION AND CONDITIONED SUPPRESSION IN SQUIRREL MONKEYS

During three experiments with squirrel monkeys, stimulus and shock pairings were given in the presence of a bite tube. Experiments 1 and 2 used a conditioned-suppression procedure in which bar pressing was reinforced with food. A transparent shield prevented biting of the bar. When the stimulus was paired with shock, bar pressing decreased (conditioned suppression) and tube biting increased during the stimulus (classically conditioned aggression). When the bite tube was removed on alternate sessions in Experiment 2, there was more suppression when the tube was present, thus suggesting that biting competed with bar pressing. However, this simple competing-response interpretation was complicated by the findings of Experiment 3 where, with naive monkeys, bar pressing was never reinforced with food, yet bar pressing was induced during the stimulus and was highest when the bite tube was absent. The fact that stimulus-induced bar pressing developed indicates that bar pressing in conditioned-suppression procedures, suppressed or not, may be maintained by two types of control—the food reinforcer and induced CS control. The higher rate of induced bar pressing during the stimulus with the bite tube absent confounds a simple competing response interpretation of conditioned suppression. It suggests that shock-induced responses during conditioned suppression could be both contributing to and competing with responding maintained by food, with the net effect depending on specific but ill-defined features of the situation.     

The effects of phencyclidine and chlordiazepoxide on target biting of confined male mice

Target-biting of confined mice increases following delivery of tail shock and decreases during a tone that precedes the shock. Both phencyclidine and chlordiazepoxide reduced biting (dose dependently) following shock and had no effect on biting during the tone. These observations are discussed in reference to previous reports, which infer that the effects of phencyclidine and chlordiazepoxide on aggression might depend upon the baseline rate of the behavior.     

Evaluating the duration of the competing response in habit reversal: a parametric analysis.

The effectiveness of habit reversal was compared across three different competing response (CR) durations. Results showed that 1‐min and 3‐min CR durations were associated with short‐term and long‐term increases in nail length for people who bit their nails. A 5‐s CR duration produced immediate increases in nail length that were not maintained. Social validity data were consistent with these findings.     

The effects of tail shock on target-biting behavior of confined mice

Mice that are confined in a narrow cylinder readily bite inanimate targets. The following studies were conducted to determine the effects of tail shock on the target biting behavior of two strains of mice. During 20-min daily sessions, ten tail shocks were administered on a fixed-time 2-min schedule. One group of mice received a tone-conditioned stimulus (CS) which terminated with the onset of the shock, and a second group of mice did not. Target bites were collected in eight 15-sec bins over the 2-min trial and cumulated over the session. It was observed that tail shock was followed by an increase in target biting and that there was a comparatively high intershock interval biting rate. In addition, intershock interval biting was suppressed for the duration of the CS. These observations are discussed in terms of the utility of this paradigm for the psychopharmacological assessment of aggressive behavior.