Extinction Schedule Research Articles

A test for both positive and negative response summation in the pigeon

Four pigeons were trained to keypeck on a multiple variable interval-extinction schedule, in which different composite stimuli were associated with the variable interval and extinction schedules. The six composite stimuli used were compounds of houselight (on or off) and form (horizontal line, vertical line, or cross) on the response key. Composite stimuli were constructed in such a way that some components of houselight or form were more frequently associated with reinforcement or extinction. It was found that the composite stimulus formed of components most frequently associated with extinction controlled a lower response rate than other composite stimuli associated with extinction. However, the composite stimulus formed of components most frequently associated with reinforcement did not control a higher response rate than other reinforced stimuli.

Autoshaping accurate discriminations in pigeons

Nine naive pigeons were autoshaped, and learned a discrimination based on a multiple variable-interval 3-min extinction schedule of reinforcement. All birds learned rapidly and made few errors. Tests for behavioral contrast indicated that none was produced. As transfer tests, six birds were shifted to a schedule that caused a reversal of the discrimination they had mastered; three birds were shifted to a new nonreversed discrimination. Both transfer tasks were learned with errors but without behavioral contrast. The reversal shift was learned more rapidly than the nonreversal shift.

A LOCAL‐RATE‐OF‐RESPONSE AND INTERRESPONSE‐TIME ANALYSIS OF BEHAVIORAL CONTRAST1

Three pigeons were exposed to a two-component multiple schedule in which a variable-interval 3-min schedule was always in effect in one component. The schedule in the other component was either variable-interval 3-min or extinction in alternate blocks of sessions. When the schedule was changed from multiple variable-interval 3-min variable-interval 3-min to multiple variable-interval 3-min extinction in the second and fourth phases of the experiment, overall response rates in the unchanged variable-interval 3-min component increased in two pigeons. Response rate declined when the schedule was changed to multiple variable-interval 3-min variable-interval 3-min again. Correlated with increases in overall response rate in the unchanged component were increases in local response rates at the beginning of the unchanged component and immediately after food presentation. Local rates 40 sec after food presentation did not increase greatly in the presence of the multiple variable-interval 3-min extinction schedule. An interresponse time analysis of three local rate samples showed small increases in the relative frequency of short-duration interresponse times at the beginning of the unchanged component and immediately after food presentation. Neither the postreinforcement pause nor the latency to the first response in the unchanged component changed systematically.

Effects of modulated very high frequency fields on specific brain rhythms in cats

The effects of exposures to low intensity (1 mW/sq.cm or less), very high frequency (VHF) (147 MHz) electrical fields, amplitude-modulated at biological frequencies (1–25 Hz), were studied on untrained and conditioned chronically implanted cats. The fields were applied between two aluminum plates (identical voltages, 180° phase shift) firmly anchored to the floor of an isolation booth, especially designed for use of VHF fields. The animals were restrained in a hammock, the longitudinal axis of the body kept parallel to the field plates. EEG and EOG were recorded through a system of low pass filters on a Model 6 Grass electroencephalograph and an Ampex FR 1100 tape recorder; behavior was continuously observed through a closed circuit TV. A series of animals was operantly trained to produce specific transient brain rhythms following periodic (every 30 sec) presentations of a light flash stimulus. The levels of performance were established (visual and spectral analysis) during conditioning and extinction schedules for a series of cats submitted to VHF fields amplitude-modulated at the dominant frequencies of the selected transient patterns and for a control group, in the absence of fields. The irradiated animals differed markedly from the control group in the rate of performance, accuracy (in terms of frequency bandwidth) of the reinforced patterns and resistance to extinction (minimum of 50 days versus 10 days). The specificity of the frequency of the modulation was tested on another group of untrained animals where spontaneous transient patterns were used to trigger for short epochs (20 sec following every burst) the VHF fields amplitude-modulated at various frequencies. The experimental results indicated clearly that the fields were acting as reinforces (increasing the rate of occurence of the spontaneous rhythms) only when modulated at frequencies close to the biologically dominant frequency of the selected intrinsic EEG rhythmic episodes. Various possible routes of interaction between the external fields and the CNS are discussed, and the hypothesis is offered that the amplitude-modulated VHF fields could influence the excitability of neuronal membranes.

The effects of lesions in the ventromedial nucleus of the hypothalamus on behavioral contrast in rats

Rats with lesions in the ventromedial nucleus of the hypothalamus displayed significantly greater positive behavioral contrast effects than did controls on a multiple VI extinction schedule, supporting the hypothesis that animals with ventromedial lesions are more responsive than controls to changes in reinforcement contingencies. Also supporting this hypothesis was the finding that three of the four lesioned animals displayed negative behavioral contrast effects on a multiple VI VI schedule which followed the multiple VI extinction schedule, whereas none of the five control animals displayed negative contrast. Manipulations involving shifts in reinforcer quality were inconclusive. It was concluded that some of the current hypotheses regarding the behavioral consequences of ventromedial lesions are in need of revision.

Durable behavior facilitating effects of discriminative stimuli

Pigeons with a past history of key pecking for an auditory conditioned rein forcer (tone) in one component of a multiple schedule, while the conditioned and primary rein forcers were paired in another component, were put on an extinction schedule in which key pecking no longer produced the tone. The key pecking persisted in the absence of the tone but ceased when the discriminative stimulus (red key light) was replaced with a novel stimulus (yellow key light).

Conditioned suppression and discriminative control of behavior

Rats were trained on a multiple variable-interval extinction schedule of reinforcement. The effects of a stimulus which preceded an unavoidable shock were assessed when it was superimposed on both components of the schedule or on VI components only. In general, VI responding was suppressed during the preshock stimulus. There was no evidence for any increase in responding during extinction components either generally or differentially during the preshock stimulus. These findings fail to support an earlier suggestion that a preshock stimulus may impair discrimination performances.

Effects of stimulus control and deprivation upon discriminative responding.

Discriminative responding in pigeons was studied under multiple variable-interval extinction schedules in which extinction was correlated with either a tone or a white keylight. The two procedures resulted in weak and strong stimulus control, respectively. In the first experiment, there was no interaction between schedule components when stimulus control was strong and reinforcement was omitted under the previously reinforced component. However, there was marked induction between components when stimulus control was weak and responding was extinguished under the previously reinforced component. In the second experiment, hours of food deprivation was varied under two levels of stimulus control. Deprivation mainly influenced response rates under the extinction stimulus, with greater absolute rate increases occurring the lower the existing level of stimulus control. Increases in responding during the extinction stimulus were four times as great from 24 to 72 hours of deprivation as from 24 to 48 hours under conditions of both high and low stimulus control.

Secondary reinforcement and information as determinants of observing behavior in monkeys (Macaca mulatta)

Responses on a food lever were reinforced on alternating Variable Ratio and Extinction schedules, while concurrent responses on an observing lever produced positive and negative cues correlated with the two schedules. In Experiment I the Variable Ratio requirement was reduced, thereby increasing the density of reinforcement in the presence of the positive cue but reducing average uncertainty as to the effective schedule. The result was a reduction in observing response rates. In Experiment II uncertainty was reduced through presentations of an informative light rather than primary reinforcement, and again the result was a decrease in observing behavior. In Experiment III presentations of the negative cue associated with nonreinforcement were discontinued, and omission of this presumably aversive stimulus again significantly reduced observing behavior. These results were interpreted as generally supporting an information analysis of observing behavior.

Effect of caudate and frontal lesions on acquisition and extinction of an operant response

Rats suffering bilateral caudate lesions, destruction of the frontal neocortex (control animals), and unoperated rats were given long experience with CRF (continuous reinforcement) and then shifted to a simple extinction schedule. Twice during the extinction phase of the experiment, the animals were given 30 response-contingent reinforcements. The animals with caudate lesions did not respond at higher levels during CRF training, but responded significantly more during the extinction sessions. An activity measure was taken of all animals 1 hr before and 3 hr after certain training sessions. The lesioned animals were found to be more active than the unoperated animals during both of these periods.

SUSTAINED BEHAVIORAL CONTRAST IN CHILDREN1

Children were exposed to a multiple schedule involving equal variable-interval schedules in each of two components and a multiple schedule involving a variable-interval schedule in one component and an extinction schedule in the other. Response rates were equal in both components when each involved a variable-interval schedule. Response rates differed in the two components of the multiple variable-interval extinction schedule. Response rates were higher in the variable-interval schedule when the accompanying schedule was extinction than when it was variable interval. The increase in response rate in the variable-interval component, simultaneous with the decrease in response rate in the extinction component, illustrated sustained behavioral contrast, and was the first evidence of this phenomenon in children.

Some determinants of behavioral contrast in pigeons and rats

In Expt. 1, pigeons trained on a multiple variable interval, extinction schedule, showed a positive contrast effect by comparison with control groups trained with S+ only, provided that the interval between stimulus presentations was short (10 sec), but not when it was long (60 sec). Positive contrast also occurred more readily with an easier discrimination, and its appearance was highly correlated with the temporary appearance of transient contrast effects. Although a longer interval between trials produced an overall increase in rate of responding in subjects trained only with S+, it was suggested that this at best represented a different type of contrast effect. In Expt. 2, rats showed positive contrast to S+ when S− was correlated with a lower frequency of reinforcement, but not when it was correlated with a reduced magnitude of reinforcement. The results were discussed in terms of frustration theory.

REINFORCEMENT DELAY: SOME EFFECTS ON BEHAVIORAL CONTRAST1

Thirty five White Carneaux pigeons first received 20 sessions of non-delayed reinforcement according to a multiple variable-interval 1-min variable-interval 1-min schedule. For the remaining 15 sessions, subjects were assigned to one of five groups, with seven subjects per group. Four of these groups involved reinforcement according to the same multiple schedule as before, but reinforcement during one of the components was delayed for either 2.5, 5, 10, or 120 sec. The schedule for the fifth group was changed to multiple variable-interval 1-min extinction schedule of reinforcement. While some subjects in all groups showed behavioral contrast, it occurred more consistently in the groups involving extinction or the longer delays of reinforcement. Groups involving the various durations of delayed reinforcement or even extinction during the altered component did not, however, show a statistically significant difference in the amount of behavioral contrast. It was suggested that neither a reduction in reinforcement frequency nor response rate during the altered component is necessary to the production of behavioral contrast.

The effects of signaled response-independent shocks on behavior under avoidance and extinction schedules

Response rates of rats were recorded during a 30-sec signal (CS) which preceded a response-independent electric shock when: (1) baseline avoidance shocks were withheld during the signal; (2) baseline avoidance shocks were available during the stimulus; and (3) baseline avoidance shocks were withheld but a response-independent shock was intruded on each trial at the midpoint of the signal. Two different adjusting avoidance baselines were used. The data suggest that the signal suppresses responding, but also that this effect can be overcome by shocks supplied either from the baseline schedule or intruded on a response-independent schedule.

Evidence of interaction between deprivation effects and stimulus control.

Discriminative responding in pigeons was studied under multiple variable-interval extinction and variable-ratio extinction schedules, as deprivation was varied. Generally, the greater the accuracy of discrimination that developed during training, the smaller the effect of deprivation upon subsequent performance. This was true both in terms of changes in response rates, and in the relationship between response rates during food reinforcement and extinction. When discrimination was inaccurate, increases in deprivation resulted in disproportionate increases in responding during extinction, as compared to increases during food reinforcement components of the schedule. The results suggest that as stimulus control (accuracy) of responding increases, discriminative performance becomes less and less susceptible to influence by deprivation.

SOME EFFECTS OF PUNISHMENT SHOCK INTENSITY UPON DISCRIMINATIVE RESPONDING

Three pigeons received visual discrimination training under both multiple variable-ratio extinction and variable-interval extinction schedules. All birds developed nearly perfect discrimination. When punishment for every tenth response during food reinforcement was presented, responding decreased as shock intensity increased. At the same time, responding during extinction, which was not punished, increased at intermediate punishment intensities, but returned to low levels under severe punishment. A second procedure, in which punishment and no-punishment sessions alternated unsystematically, was employed with two of the birds. The results under this procedure essentially replicated the data obtained as punishment shock intensity increased gradually.

Use of home observations as an integral part of the treatment of depression; preliminary report and case studies.

This paper describes the use of observation of the patient's interaction with his spouse and children in his own home as a part of the assessment and treatment of depression. Home observations are conducted during the beginning, middle, and ending phases of treatment. Interactions are coded in terms of the behaviors emitted by the patient and the social consequences of his behavior. The home observations are used to define treatment goals and to measure behavior change. In addition, home observations have beneficial consequences in that they (a) immediately focus the therapist-patient interaction on behavioral and interpersonal problems, and (6) provide a way of involving a significant part of the patient's environment in the treatment process. Some preliminary data are presented which are consistent with the hypothesis that a low rate of positive reinforcement is a critical antecedent condition for the occurrence of depressed behaviors. This is one of a series of reports describing the treatment of depression2 from a behavioral point of view (Lewinsohn & Atwood, 1969; Lewinsohn & Shaw, 1969; Lewinsohn, Weinstein, & Alper, 1970). The major assumptions underlying the approach are (a) a low rate of positive reinforcement acts as an eliciting stimulus for some depressive behaviors such as verbal statements of dysphoria, fatigue, and other somatic symptoms; (b) a low rate of positive reinforcement constitutes a sufficient explanation for other parts of the depressive syndrome such as the low rate of activity and verbal behavior. For the latter, the depressed person is considered to be on a prolonged extinction schedule; (c) the social environment provides reinforcement in the form of sympathy, interest, and concern which strengthens and maintains depressive behaviors; (d) a number of different environmental events (e.g.,

Trial-and-error behaviour of inbred and F 1 hybrid mice

The trial-and-error behaviour of male C57 BL Tb A2 G Tb and F 1 mice was investigated in apparatus in which pressing a lever can release a pellet of food. A2 G Tb mice had the highest basic unrewarded pressing rate. C57 BL Tb mice learned to press the lever for food as readily as F 1 mice and more readily than A2 G Tb mice, despite being slowest to start pressing the lever. Response rates rose as the frequency of reward was reduced from one pellet every press to 1 : 50 presses. Hybrid mice tended to perform more efficiently than their inbred parents on the 1 : 5 and 1 : 10 schedules. The rate of pressing by A2 G Tb mice continued to increase on very low ratios of reward, but that of C57 BL Tb mice fell markedly. A2 G Tb mice tended to be the most efficient when restraint was rewarded (not pressing the lever during a delay before the arrival of the pellet), but their superiority disappeared on the longest delay. On extinction schedules, in which lever-pressing was no longer rewarded, the classes differed little. Over all, the hybrid mice were more efficient than either inbred parent strain.

A comparison between the reinforcing and discriminative functions of a stimulus

After learning a discrimination based upon illumination change, seven rats were exposed to an extinction schedule in which lever presses during the previously negative stimulus caused the previously positive stimulus to come on and vice versa. Response rates remained much higher in the presence of the positive stimulus than in the negative, arguing against Dinsmoor's suggestion that the reinforcing and the discriminative effects of a stimulus are quantitatively identical. It is suggested that Dinsmoor's own results arose because his measure of secondary reinforcement was strongly “contaminated” by direct discriminative effects of the stimulus. A computer simulation is used to show that exact coincidence of discriminative and reinforcing effects in these circumstances is not so unlikely as Dinsmoor had supposed.

Resistance to extinction as a function of acquisition and extinction schedules and type of measurement

Thirty albino rats were conditioned to bar-press for water under either continuous or 45-sec fixed-interval reinforcement schedules. Extinction was then carried out with either zero reinforcements, omission training, or noncontingent 45-sec fixed-interval reinforcements. Resistance to extinction was measured by the number of bar presses, the time, and the rate of responding to a no response for 15 min criterion. It was concluded that the measure taken would affect many of the conclusions from extinction studies.