Two parameters of a temporally defined schedule of negative reinforcement

Temporal schedules of negative reinforcement were derived in a manner analogous to those for positive reinforcement, and two parametric studies were carried out with two of the three defining variables. With some limiting values of the defining variables, escape schedules result and data obtained at these values were similar to those obtained in escape studies. At other values of the defining variables avoidance behavior was generated.     

Effects of cycle length on performance on a temporally defined avoidance schedule

Three rats were trained on a temporally defined avoidance schedule logically similar to a fixed-interval, limited-hold positive reinforcement schedule. This avoidance schedule was composed of time periods during which responses had no scheduled consequences alternating with time periods during which a response precluded shock. As with fixed-interval length and response rate on positive reinforcement schedules, an inverse relationship was obtained between the length of the no-consequence interval and response rate during the no-consequence interval. An inverse relationship was also obtained between the length of the no-consequence interval and the per cent of shocks avoided. A rate increase within the no-consequence interval, similar to that typically produced by fixed-interval positive reinforcement procedures, was displayed by one of the rats where the no-consequence interval was at intermediate values and frequency of shock was relatively high. The introduction of a discriminative stimulus correlated with the avoidance interval produced typical discriminated avoidance behavior as well as alterations in temporal patterning of responses during the no-consequence interval in the two rats exposed to this procedure. These alterations in temporal patterning disappeared when the discriminative stimulus was removed. The results were consonant with those reported in the literature involving food reinforcement and fixed-interval, limited-hold schedules.     

Facilitation and suppression of responding under temporally defined schedules of negative reinforcement

Two parameters for scheduling aversive stimulus presentations were studied systematically by specifying concurrent and independent probabilities of electric shock delivery for the occurrence and for the non-occurrence of a lever-press response. After preliminary training on a free-operant shock-avoidance schedule, 16 rhesus monkeys were divided into four groups, each group being assigned one shock distribution on a continuum from fixed interval to a widely ranging variable interval. Within groups, each subject was successively exposed to three values of response-dependence of shock delivery on a continuum from response-independent shock to complete dependence of shock on response occurrence (“punishment”). Introduction of shock following avoidance training produced initial response facilitation followed by suppression. Responding during both the facilitation and suppression periods was maximal when the shock schedule was periodic and response independent. Responding decreased as the inter-shock intervals were made more variable across groups, and as shock delivery was made increasingly response dependent within individual subjects.     

Effects of promazine, chlorpromazine, d-amphetamine, and pentobarbital on treadle pressing by pigeons under a signalled shock-postponement schedule.

The effects of promazine on treadle pressing to postpone the presentation of electric shock were studied in three pigeons. The effects of chlorpromazine, d-amphetamine, and pentobarbital were studied in two of these pigeons. Each treadle press postponed electric shock for 20 sec and presentation of a preshock stimulus for 14 sec. Selected doses of both promazine and chlorpromazine increased the rates of treadle pressing in all birds. The response-rate increases produced by promazine and chlorpromazine were due to increased conditional probabilities of treadle pressing both before and during the preshock stimulus. d-Amphetamine (1 and 3 mg/kg) slightly increased responding in one of the birds, but not to the extent that promazine or chlorpromazine did. In the other bird, the 10 mg/kg dose of d-amphetamine increased shock rate but did not change response rate. Some doses of d-amphetamine increased the conditional probabilities of responding both in the absence of the preshock signal and during the preshock signal in both birds. Pentobarbital only decreased response rates and increased shock rates.     

The effects of differential negative reinforcement of other behavior and noncontingent escape on compliance

The present study evaluated the effects of noncontingent escape and differential negative reinforcement of other behavior in reducing problem behaviors and increasing compliance in 2 children with disabilities. Results showed that both methods reduced problem behavior and increased compliance for both children.     

Observing behavior in squirrel monkeys under a multiple schedule of reinforcement availability

Observing behavior of two squirrel monkeys was examined under a multiple schedule of four components. Lever (observing) responses produced either a stimulus indicating the availability of food or another stimulus indicating food was not available. Key responses in the presence of the food-available stimulus produced food on a continuous reinforcement schedule. In the absence of food-available stimuli, responding on the key had no scheduled consequences. Observing responses produced food-available stimuli according to three different random-interval schedules with mean interstimulus availability times of 1, 2, and 4 min. In the fourth component of the multiple schedule (observing extinction) food-available stimuli never occurred. Each component of the schedule was correlated with a distinctive auditory stimulus. Observing rates decreased with decreasing frequency of the food-available stimulus. Observing rates during extinction continued decreasing when the brief stimulus indicating food unavailability was no longer produced by lever pressing. When the brief stimulus was reinstated response rates increased abruptly.     

Effects of d-amphetamine, chlorpromazine, and chlordiazepoxide on intercurrent behavior during spaced-responding schedules.

Effects of d-amphetamine, chlorpromazine, and chlordiazepoxide on lever pressing under direct control of spaced-responding schedules were compared with effects on intercurrent drinking and wheel running in the rat. Drug effects on lever pressing were systematically related to dose and were consistent for all animals; drug effects on intercurrent behavior were generally different for each animal. In the case of lever presses, increasing doses of d-amphetamine first increased and then decreased response rate, increasing doses of chlorpromazine produced graded decreases in response rate, and doses of chlordiazepoxide up to 40 mg/kg produced no effect on response rate. These data are discussed in context with the concept of schedule control, and it is suggested that the behavioral pharmacology of intercurrent behavior be explored as a useful procedure in the experimental analysis of intercurrent behavior.     

Effects of reinforcement amount on attack induced under a fixed-interval schedule in pigeons

Key pecking by pigeons was maintained on a chained fixed-interval 4-min (12-min for 1 subject) fixed-ratio 1 schedule of food presentation. Attacks toward a restrained and protected conspecific were recorded. In the first experiment, the amount of food presented per interval was manipulated across phases by varying the number of fixed ratios required in the terminal link of the chain. Measures of attack for all pigeons during the fixed-interval component increased monotonically as a function of food amount. In the second experiment, two different food amounts alternated within each experimental session under a multiple schedule. For both pigeons in this experiment, measures of attack were higher during the component that delivered the larger food amount per interval. The differences in levels of attack induced by the two food amounts in Experiment 2, however, were not as great as in Experiment 1; apparently this was because attack during the first interval of each component was controlled in part (P-5626) or entirely (P-7848) by the reinforcement amount delivered at the end of the previous component. Attack was also a function of the location of the interfood interval within the session. For both pigeons, attack tended to decrease throughout the session. The results of both experiments suggest that attack is an increasing function of reinforcement amount under fixed-interval schedules, but that this function may be influenced by the manner in which reinforcement amount is manipulated, by the duration of the interfood interval, and by the location of the interfood interval within the experimental session. In general, these results are compatible with theories of induced attack and other schedule-induced behavior that emphasize aversive after-effects of reinforcement presentation.     

Electroencephalographic correlations of temporally spaced responding and avoidance behavior

This study was undertaken to determine whether any EEG changes occurred during a multiple schedule of reinforcement consisting of repeated periods of avoidance behavior, a time-out (TO) period, and a period of differential reinforcement of low rates (DRL). The two monkeys were permanently implanted with bipolar electrodes in various subcortical areas. The EEG was recorded from these electrodes for several weeks before any behavioral training was undertaken. Training was then begun in the multiple schedule, and EEG recordings were taken frequently throughout the training period. When a stable performance level was achieved, drugs (dl-amphetamine and sodium pentobarbital) were introduced which disrupted the DRL performance but had little or no effect on avoidance behavior. The EEG recordings continued throughout these drug studies.

The data indicate that the marked behavioral differences noted in each component of the schedule were not reflected in the EEG. However, the EEG did correlate with the general level of alertness of the animals during the various components. The drugs which differentially affected the behavior in the components of the schedule did not differentially affect the EEG, but they did change the brain-wave activity equally in all components. Finally, EEG changes correlated with the complex motor response of lever pressing were not observed.

     

Duration-reduction of avoidance sessions as negative reinforcement

Five rats were exposed to a shock-postponement procedure in which responses on each of two levers initially had equivalent effects. After an initial training sequence that ensured at least some responding on each lever, an additional consequence was made conjointly operative on the previously less-preferred lever for each animal. Each response on this lever continued to postpone shock, but also reduced the session duration by one minute. The conjoint contingencies were operative until, through session-shortening responses and the passage of time, the session was scheduled to end in two minutes; during the final two minutes the session-shortening contingency was disabled while the shock-postponement contingency continued to be operative on both levers. When responding shifted to a predominance on the session-shortening lever, the conjoint contingency was shifted to the other lever; for four of the five rats this reversal was followed by two additional reversals. Two of the rats' responding showed clear, strong, and unambiguous sensitivity to the session-shortening contingency. The responding of two others was also systematically controlled by that contingency, but the effects were less clearcut. The fifth animal showed an initial shift when session-shortening was introduced, but its subsequent behavior proved insensitive to reversals of procedure. The results clearly indicate a sensitivity of behavior to events on a time scale quite distinct from that of immediate consequences. They also support an interpretation of avoidance sessions, considered in their entirety, as events whose contingent relationship to behavior can affect that behavior—even in the absence of stimuli that delineate those relationships. Finally, these results support an interpretation of aversively based conditioning within a broader context, analogous to the “open versus closed economy” interpretation of appetitively controlled behavior.     

Effects of chlorpromazine on appetitive and aversive components of a multiple schedule

A multiple schedule having both an appetitive and an avoidance component was maintained in two dogs to create a complex behavioral base line for observing the effects of chlorpromazine. Both soluble and “Spansule” chlorpromazine generated similar functions relating drug dose to measures of behavioral output. Although the dose ranges and the drugging procedures differed markedly for the different preparations of CPZ, the functions generated were comparable. There was no evidence that chlorpromazine had a differential depressing effect as a function of type of reinforcement. At low doses, rates of responding on the food-reinforced components increased slightly, whereas rates on the avoidance components remained relatively unchanged. At higher doses, both components showed an approximately equal depression of responding. These results are discussed with reference to some of the logical and experimental difficulties inherent in making comparisons across components of a multiple schedule and across schedules in general.     

The effect of the size of the test environment on behavior under two temporally defined schedules

The effect of the size of the floor area of the operant test chamber on behavior was tested using a standard-size test chamber and a test chamber with one-fourth of the floor area of the standard chamber. Two groups of pigeons were tested under a differential-reinforcement-of-low-rate 15-sec schedule or a variable-interval 60-sec schedule. Both groups of pigeons had higher response rates while in the smaller floor area. Pigeons under the differential-reinforcement-of-low-rate schedule also showed a decrease in rate of reinforcement, an increase in ratio of responses to reinforcements, and an alteration in interresponse-time-per-opportunity distributions when tested in the reduced floor-area condition. These effects are similar to those found under physical restraint, indicating that amount of floor space available for locomotion interacts with schedule behavior and that physical restraint may be regarded as the lower limiting value of amount of floor area available for locomotion.     

Effects of schedule and magnitude of reinforcement under conditions of thirst motivation

In contrast to a recent finding (Macdonald, G. E., & De Toledo, L. Learning and Motivation, 1974, 5, 288–298.) the results of three experiments investigating various partial reinforcement (PRF) manipulations under conditions of thirst motivation demonstrated strong similarity to analogous manipulations involving food reward. Specifically, for animals receiving water reinforcement, PRF was shown to generate greater resistance to extinction than continuous reinforcement (Expt 1 & 3), the schedule of reinforcement was shown to interact with level of acquisition (Expt 1 and 2), and the magnitude of the partial reinforcement extinction effect was shown to be a function of reward magnitude (Expt 3). These results provide strong evidence that mechanisms which operate in partial reinforcement situations are highly similar, regardless of the type of appetitive reinforcement.     

Positive and negative reinforcement effects on behavior in a three-person microsociety

Three-person groups, either of males or of females, resided for 6 to 12 days in a continuously programmed environment. Subjects followed a behavioral program that determined the sequential and contingent relations within an inventory of activities. The program consisted of positive reinforcement days and avoidance days. During a positive reinforcement day, each work unit completed by a subject incremented a group account. The account was divided evenly among the three participants at the conclusion of the study. During a negative reinforcement day, no money was earned, and the group was assigned work unit criterion that, if completed, prevented a reduction in accumulated earnings. During negative reinforcement days, subjects made aggressive verbal responses, which differed in magnitude among the four groups. These differences were evident in several distinct behavioral measures. Performances on components of the work unit were not demonstrably affected by the reinforcement schedules in effect, although during the avoidance condition one subject stopped working and another subject's productivity declined.     

Signalled and unsignalled percentage reinforcement of performance under a chained schedule

Pigeons were trained to peck a key under a chained fixed-ratio 15 fixed-interval 25-sec schedule of food presentation. In Experiment 1, blocks of sessions in which 100%, 75%, 50%, and 25% of the sequences ended with food presentation were conducted. When food presentation was omitted, a timeout of equal duration replaced it. As the frequency of food presentation decreased so did the frequency of completing the chained schedule. In Experiment 2, 75%, 50%, or 25% of the sequences terminated with food presentation and outcomes were signalled, i.e., completion of the fixed ratio resulted in either a stimulus correlated with the fixed-interval 25-sec schedule or a stimulus correlated with extinction. As the frequency of food presentation decreased, the number of sequences completed per session increased for two pigeons and remained high for a third. In Experiments 3 and 4, assessments of the effects of signalling the outcome of the chained schedule were made with response-independent presentation of events at the end of the sequence. Again, signalling the outcome of the chained schedule led to more chains being completed per session than did not signalling the outcome. Stimuli differentially paired with food presentation have powerful behavioral effects that may be attributed to the potency of these stimuli as conditioned reinforcers.