Persistence of response prevention effects following retraining of escape behavior

This study evaluated the effects of response prevention procedures on the extinction of escape behavior following the reinstatement of shock-escape training prior to the start of extinction. Female hooded rats were assigned to four groups (N = 10) in a factorial design which orthogonally combined response prevention or pseudo-prevention procedures with escape retraining or no retraining procedures. Results showed that prevention reliably impaired shock-escape behavior on early retraining trials; but this effect dissipated completely by the end of retraining. In extinction, prevention reliably facilitated the extinction of escape behavior relative to that of pseudo-prevention controls; but the degree of facilitation was reliably attenuated by retraining procedures. These findings were related to the competing response interpretation of prevention effects.     

Pavlovian processes and response competition as determinants of avoidance response-prevention effects

Two experiments investigated the facilitation of avoidance extinction by exposure to lengthy (5-sec) shock during avoidance response prevention. In Experiment 1, animals exposed to light only or to light-shock pairings during response prevention showed equal facilitation of extinction relative to shock-only animals or to animals receiving no response prevention. Preshock rearing, directly antagonistic to the avoidance response, developed for shocked animals during response prevention and persisted during extinction for light-shock animals. Immediately before extinction, half of each group was permitted a single escape from a light-shock compound by means of the response previously required for avoidance. The only effect was upon the extinction performance of light-shock animals. Rearing was eliminated and extinction responding increased to a level far above that for any of the other animals. Experiment 2 demonstrated that the shock-only treatment affected the extinction performance and rearing of nonescape and escape animals in a manner entirely equivalent to the effects of the light-shock treatment of Experiment 1, provided stimulus conditions (light absent) were the same for all experimental phases. Thus, lengthy shock during avoidance response prevention simultaneously leads to the acquisition of competing behavior and enhances control by a warning signal or contextual stimuli over the avoidance response. Implications for the CS-only response-prevention treatment and the transfer of aversive control are discussed.     

An animal analogue to systematic desensitization and elimination of avoidance

Rats first acquired a two-way avoidance response to a discrete warning signal (80 db white noise.) The effects of 3 experimental and 3 control treatments on elimination of the response were evaluated on a nonshock posttreatment extinction test. Group Systematic Desensitization (SD) received graded exposure to the warning signal while they were eating. Rats in Graded Hierarchy (GH) and Extinction (Ext) groups were yoked to Ss in the SD group such that GH and Ext treatment was identical with that of SD except that neither group ate and the Ext group was exposed to the full intensity warning signal (nongraded exposure) on all trials. None of the control groups was exposed to the warning signal between acquisition and the posttreatment test. Results indicated that SD, while interfering with avoidance during treatment, did not differ in effectiveness from control treatment and was significantly less effective than GH and Ext, when avoidance was tested in extinction. It was suggested that the present analogue SD technique impaired S's reception of (exposure to) the warning signal during treatment.     

Extinction effects following interpolation of instrumental trials among response prevention periods

Two experiments evaluated the effectiveness of response prevention when prevention periods were interpolated with instrumental trials which permitted performance of the originally trained instrumental behavior. In Experiment 1, interpolation of instrumental escape trials under shock and nonshock procedures reliably reduced prevention's influence on performance and yielded extinction responding similar to that of pseudo-prevention controls. In Experiment 2 interpolation of instrumental escape trials under nonshock conditions yielded passive avoidance performance similar to that of pseudo-prevention controls but reliably different from that of a regular prevention group.     

Effects of temporal placement of response prevention on extinction of avoidance in rats

Two experiments investigated the effects of prior extinction trials upon the effectiveness of response prevention procedures (flooding) in facilitating extinction of avoidance in rats. The results showed that both prior CS only extinction trials and response prevention independently hastened extinction and that response prevention is enhanced if prior extinction has already taken place. The results were interpreted as being consistent with a relaxation interpretation of extinction of avoidance behavior providing a ‘distraction’ or ‘attention shift’ factor is incorporated into theory.     

Extinction of avoidance behavior and the problem of residual fear

According to two-factor theory, avoidance responding is predicated on a conjoint relationship between Pavlovian and instrumental conditioning. Recently a variety of evidence has indicated that these processes are independently subject to experimental manipulations, both during acquisition and extinction. The latter finding is paralleled in the clinicial literature by the observation that the elimination of an avoidance response does not adequately reflect concurrent changes in autonomic and verbal behavior. These findings suggest the need for multiple measures of anxiety in assessing the effect of experimental and therapeutic operations on avoidance behavior. This paper also calls attention to the discriminative and reinforcing properties of the CS in an attempt to account for these findings.     

Punishment of an extinguishing shock-avoidance response by time-out from positive reinforcement

Two experiments were conducted to determine the effects of punishment by time-out from positive reinforcement on the extinction of discriminated shock-avoidance responding. Subjects were trained initially to bar press for food on an intermittent schedule of reinforcement and, concurrently, to avoid shock at the onset of a warning signal. Experiment I compared avoidance extinction performance under no punishment and when avoidance responding resulted in a 30-sec TO from reinforced appetitive responding. In Exp II, the contingent use of TO punishment was compared with its random, or noncontingent use. The results of both experiments showed that in the absence of punishment, avoidance extinction was characterized by short latencies and nearly 100% avoidance responding. Avoidance responding in extinction was little affected by noncontingent TO punishment. When TO was made contingent upon avoidance responding, however, avoidance latencies immediately increased and the frequency of avoidance responses subsequently decreased to zero.     

Occasional reinforced responses during extinction can slow the rate of reacquisition of an operant response

Three experiments with rats examined reacquisition of an operant response after either extinction or a response-elimination procedure that included occasional reinforced responses during extinction. In each experiment, reacquisition was slower when response elimination had included occasional reinforced responses, although the effect was especially evident when responding was examined immediately following each response-reinforcer pairing during reacquisition (Experiments 2 and 3). An extinction procedure with added noncontingent reinforcers also slowed reacquisition (Experiment 3). The results are consistent with research in classical conditioning (Bouton, M. E., Woods, A. M., & Pineño, O. (2004). Occasional reinforced trials during extinction can slow the rate of rapid reacquisition. Learning & Motivation, 35, 371-390) and suggest that rapid reacquisition after extinction is analogous to a renewal effect that occurs when reinforced responses signal a return to the conditioning context. Clinical implications are also discussed.     

Extinction of avoidance in rats: response availability and stimulus presentation effects

A conditioned a versive stimulus presented in prolonged, continuous fashion is said to be flooded. Using a two-way shuttle avoidance task. Polin (1959) found that animals allowed to respond to flooded stimuli extinguish faster than animals prevented from responding to discrete stimuli of equal total duration. But, as Shearman (1970) noted, the CS presentation and response availability factors were confounded. He arranged them factorially, in a 2 × 2 design, again utilizing two-way avoidance, but found no differences between any of the experimental groups, although all groups extinguished faster than a regular extinction control group, the only group for which CS termination was response-contingent. Since there is evidence from one-way avoidance studies that response prevention facilitates extinction of avoidance with CS exposure held constant (Shipley et al., 1971). we repeated the Shearman design, using a one-way avoidance paradigm, and including a group for whom the aversive CS would be presented in discrete trials at increasing intensities. A separate aspect of the present investigation concerned the measurement of a fear response as well as the avoidance response. Results of several investigations have shown (e.g. Coulter et al. 1969; Linton et al.. 1970) that avoidance behaviour can be extinguished without the extinction of fear. It was thought useful to assess the generality of this result, since in two-factor theory, fear and avoidance are related.Two supplementary experiments replicated important conditions of the initial one, while examining whether response prevention and response non-availability have similar effects (II), and the relation between the fear test and the test for extinction (III).     

Differential pavlovian fear conditioning as a function of the qualitative nature of the UCS: Constant versus pulsating shock

Dogs were trained in a shuttlebox to perform an instrumental avoidance response to a visual signal. Then, while pharmacologically immobilized in a hammock, they received differential Pavlovian fear conditioning with two tones: one paired with a constant shock and one with a pulsating shock. During Pavlovian conditioning EKG’s were recorded. Later, in the shuttlebox, Ss received tests for the transfer of control of avoidance responding. Although no significant heart rate differences were found,Ss hurdled the barrier significantly more quickly in response to the tone previously paired with the pulsating shock than to the tone paired with the constant shock, indicating that pulsating shock results in better fear conditioning.     

On the independence of stimulus evocation of fear and fear evocation of responses

Dogs in an experimental group were first trained in a shuttlebox on a free-operant avoidance response; then a second, discriminative avoidance response was trained in a second apparatus to a tone. Following criterion, the second avoidance response was “extinguished” through unsignaled. response-independent US presentations. Finally, the tone was presented in the shuttlebox as a test for residual fear. The tone produced as much facilitation of the free-operant avoidance responding as it did in two control groups; one control had not had the second avoidance response extinguished, while the other had received only Pavlovian conditioning in the second apparatus. Thus, the elimination of a discriminative avoidance response to a CS does not impair the CS's ability to control a second independent avoidance response. This result reflects and confirms the separability and independence of the CS-fear and fearavoidance response links hypothesized by two-process theories.     

Facilitation of discriminated lever-press avoidance by noncontingent shocks

Two experiments investigated the effect of presenting a brief noncontingent, unsignaled shock prior to warning-signal onset on discriminated lever-press avoidance behavior in rats. The main finding was that noncontingent shock delivered 2 sec but not 16 sec prior to warning-signal onset facilitated avoidance performance and learning. These results were predicted on the basis of shock-elicited response bursting which was expected to increase the operant level of the lever-press response at short shock-warning signal intervals. It was suggested that species-specific limitations on rats' lever-press avoidance are not unconditional, but rather can be overcome with environmental manipulations.     

EFFECTS OF WARNING STIMULI FOR REINFORCER WITHDRAWAL AND TASK ONSET ON SELF-INJURY

Results of a functional analysis of self-injurious behavior (SIB) in a child with autism showed that her SIB was maintained by access to preferred objects and escape or avoidance of task demands. Extinction and noncontingent reinforcement treatments were supplemented by presenting a statement combined with a picture cue at 30-s intervals indicating that a preferred object would be removed or a task would be presented. Warning stimuli in combination with extinction and noncontingent reinforcement reduced SIB to acceptable levels. SIB rates remained comparatively high in a control condition consisting of a 2-min delay to onset of reinforcer removal or task demands.     

Using drugs to modify the effect of response prevention on avoidance extinction

Amobarbital and chlordiazepoxide were administered during avoidance response prevention and the effect evaluated in the nondrugged state in a subsequent test for avoidance extinction. It was found that Ss administered 15 mg/kg and 30 mg/kg amobarbital, and 30 mg/kg chlordiazepoxide during response prevention differed significantly from the control Ss in extinction performance. Rather than showing either reduced avoidance performance or no difference with the nondrugged Ss, the Ss drugged during response prevention showed increased avoidance performance in the subsequent test of avoidance extinction. That is, preventing avoidance responding under a drugged (versus nondrugged) state produced increased resistance to extinction of the avoidance response.     

Lever attacking and pressing as a function of conditioning and extinguishing a lever-press avoidance response in rats

Six experimental rats were conditioned to press one of two available levers to avoid shock. The levers registered bites as well as presses. For four of these rats, shock was contingent on lever bites when a specified time period had elapsed after the previous shock. An extinction period, in which only periodic noncontingent shocks were presented, followed avoidance training. Six yoked-control rats received the same sequence of shocks as did the corresponding experimental rats in both the conditioning and extinction phases. All six experimental rats repeatedly bit the avoidance lever. Four bit it more than the nonavoidance lever during conditioning, and five bit it more during extinction. Five of the six experimental rats consistently bit the levers many more times during each session than did their respective control rats, suggesting that avoidance conditioning facilitated lever biting. Rates of lever biting and pressing by all of the experimental rats and by some of the control rats were highest immediately following shock throughout both phases. During later portions of the intervals following shock, characteristic effects of conditioning and extinction were observed. This finding suggests that extinction of avoidance behavior by unavoidable shock presentations can be demonstrated more readily when shock-elicited responding is extricated from the data.     

Effects of expectancies of different reward magnitudes in transfer from noncontingent pairings to instrumental performance

In two experiments, rats received noncontingent pairings of two stimuli with food reward, one paired with small reward and the other with large reward, and received bar press training with large reward or with small reward. When the noncontingent stimuli (NS) were presented for test during subsequent rewarded bar pressing and during early extinction of bar pressing, responding for each group was faster in the presence of the NS which was paired with the same reward magnitude that group received in bar press training than to the NS which had been paired with a different reward magnitude. As extinction progressed, all groups responded more slowly in the presence of the NS which had been paired with the large reward than in the presence of the NS which had been paired with small reward. These results were interpreted as indicating that responding in the presence of an NS depends on: (i) whether the reward expectancy elicited by the NS has been conditioned to the instrumental response, and (ii) the relationship between the reward expected in the presence of the NS and that received in test.     

Control of avoidance by a response-produced stimulus

Three pigeons were trained to press a foot pedal to postpone electric shock. The safety signal was a tone of 1000 Hz, which sounded for 5 sec following each press; silence therefore served as a warning signal. After the performance approached asymptote, test sessions were interspersed among the training sessions. Following a warm up, the shock was omitted (extinction), and no tone or a tone of 250, 500, 1000, 2000, or 4000 Hz was presented following each press for the remainder of the session. Gradients of generalization plotted in terms of the number of times the tone was produced on each test peaked at 1000 Hz, indicating that the performance was controlled by the frequency. Since this dimension is orthogonal to absence of tone, the gradient cannot be attributed to differences in the magnitude of change in the warning signal. It was concluded that response-produced stimuli reinforce avoidance behavior.     

Relative persistence of avoidance and positively reinforced behavior

In one experiment with rats, and a second with pigeons, subjects were trained on a schedule in which identical response dependencies applied to intermittent receipt of positive reinforcement (PR) for one group and avoidance (AV) of shock for a second group. After obtaining comparable stable training performance for groups PR and AV, persistence tests were conducted with a traditional extinction (EXT) procedure vs. response-independent (FREE) delivery of positive reinforcers or shocks. In both experiments, response elimination was rapid in EXT for groups PR and AV, and responding tended to be maintained in groups PR and AV in the FREE persistence test. These results contradict the widely held assumption that avoidance behavior is unusually resistant to extinction, and they call for a re-examination of elimination of avoidance responding.     

Dual effects of response blocking following avoidance learning

It was shown that either enhanced or decreased avoidance responding by rats could be produced by the same response blocking procedure occurring after avoidance training. The particular result produced depended on (1) the duration of the blocking trial and (2) when during the retention interval the blocking trial occurred. Results were interpreted in terms of a memory reactivation explanation and implications for the therapeutic uses of extinction were discussed.     

Recovery of an overshadowed association achieved by extinction of the overshadowing stimulus

Three experiments are reported in which conditioned lick suppression by water-deprived rats was used as an index of associative strength. In Experiment 1, overshadowing of a light by a tone was observed when the light-tone compound stimulus was paired with foot shock. After initial compound pairings, the tone-shock association was extinguished in one group of subjects. Subsequently, these animals demonstrated significantly higher levels of suppression to the light relative to a control group in which the tone had not been extinguished. Experiment 2 replicated this effect while failing to find evidence to support the possibilities that extinction presentations of the overshadowing tone act as retrieval cues for the light-shock association, or that, via second-order conditioning, the light-shock association is actually formed during extinction of the tone. Experiment 3 determined that the recovery from overshadowing observed in Experiments 1 and 2 was specific to the extinction of the overshadowing stimulus rather than the extinction of any excitatory cue. Collectively, these results suggest that the debilitated response to an overshadowed stimulus does not represent an acquisition failure, but rather the failure of an acquired association to be manifest in behavior.