Uncontrollable shock proactively increases sensitivity to response-reinforcer independence in rats

Learned helplessness theory predicts that animals exposed to inescapable shock acquire an expectancy of response-reinforcer independence, which proactively interferes with learning of response-reinforcer dependence. The theory also predicts that this expectancy can increase sensitivity to subsequent instances of response-reinforcer independence. These experiments test the latter prediction in a paradigm that minimizes the confounding effects of shock-induced activity deficits. Rats were trained to respond for food, then given either escapable, inescapable, or no shock. Subsequently, they received two sessions of response-contingent food followed by sessions of noncontingent food deliveries. During this phase, inescapably shocked animals decreased responding faster than did controls. Experiment 2 replicated this finding with a different schedule of food delivery and a procedure that more directly minimized the possibility that the outcome is due to either direct or indirect shock-induced activity changes. These results support the prediction that uncontrollable aversive events can increase an animal's sensitivity to noncontingent response-reinforcer relationships.     

Frustation and learned helplessness.

This article reports the transfer of learned helplessness from one aversive motivator, shock to another, frustration. In experiment 1, animals were trained to approach food in a runway and concomitantly exposed to either escapable, inescapable, or no shock in a different situation. Extinction was conducted in the runway, and subsequently the animals were tested for hurdle-jump escape from the frustrating goal box. Inescapably shocked rats failed to learn to hurdle-jump, whereas escapably or nonshocked animals learned the frustration escape response. Experiment 2 replicated the basic finidngs of Experiment 1 and showed transfer of learned helplessness from shock to frustration when no running response had been first acquired in the runway.     

Instrumental to Pavlovian transfer: Learning about response-reinforcer contingencies affects subsequent learning about stimulus-reinforcer contingencies

Two experiments examined the interaction between response-reinforcer (R-S) and stimulus-reinforcer (S-S) learning. In both experiments, three groups of rats were exposed to escapable, yoked inescapable, or no shocks. All groups were then exposed to either two or four sessions of truly random control (TRC) conditioning (Experiment 1) or to an excitatory conditioning procedure (Experiment 2) in which the shock US occurred with either moderate or low probability. Excitatory strength of the CS was assessed during extinction by a conditioned emotional response (CER) test. Inescapably shocked rats conditioned less than did their escapably shocked and nonshocked partners under all TRC conditions of Experiment 1, but only conditioned less than their partners in Experiment 2 when exposed to the moderate CS-US contingency for four sessions. These results provide a clear demonstration of transfer between instrumental training and Pavlovian excitatory conditioning and thus, support the influence of learning about R-S contingencies upon subsequent learning about S-S contingencies. Both a contextual blocking interpretation and an expansion of the learned helplessness theory were discussed as possible explanations of this transfer.     

Feedback during exposure to inescapable shocks and subsequent shock-escape performance

In two experiments, we assessed the ability of a feedback stimulus during helplessness training to reduce the performance deficits common to inescapable shock. In each experiment, four groups of rats were exposed to either escapable shock (E), inescapable shock with a feedback stimulus following shock termination (Y-FS), inescapable shock with no feedback stimulus (Y-NFS), or no shock (N). The feedback stimulus eliminated the interference effects of inescapable shock when tested with an FR-3 lever press escape task (Experiment 1) or on an FR-1 task with a 3-s delay between the response and shock termination (Experiment 2). These results suggest that stress-induced biochemical changes may mediate the interference effects seen in inescapably shocked rats.     

Learned helplessness in the rat.

Four experiments attempted to produce behavior in the rat parallel to the behavior characteristic of learned helplessness in the dog. When rats received escapable, inescapable, or no shock and were later tested in jump-up escape, both inescapable and no-shock controls failed to escape. When bar pressing, rather than jumping up, was used as the tested escape response, fixed ratio (FR) 3 was interfered with by inescapable shock, but not lesser ratios. With FR-3, the no-shock control escaped well. Interference with escape was shown to be a function of the inescapability of shock and not shock per se: Rats that were "put through" and learned a prior jump-up escape did not become passive, but their yoked, inescapable partners did. Rats, as well as dogs, fail to escape shock as a function of prior inescapability, exhibiting learned helplessness.     

习得性无助是习得的吗？——对习得性无助理论及其反思的评述

Seligman和Maier（1967）在动物实验的基础上提出了著名的习得性无助理论,但在2016年,Maier和Seligman二人却联合发文对该理论进行了反思：从最新的神经生物学证据来看,习得性无助的经典理论概括存在基本错误,习得性无助并非习得而来！所谓“习得性”无助,实质上是动物对厌恶刺激长期作用的先天适应性反应,而非认知学习的结果。本文简要梳理习得性无助理论的起源与发展,深入分析这一反思的核心内容、依据及意义,对其中否定习得性无助理论概括的观点,从证据的充分性、研究范式的效度、规范概念等角度作了进行进一步的探讨,并结合新的实验范式对未来研究提出建议。     

Therapy and immunization of long-term analgesia in rats

Three experiments are reported which examine the effects of experience with escapable shock either subsequent to (Experiment 1) or prior to (Experiments 2 and 3) a session of inescapable shock on the subsequently produced long-term analgesic reaction in rats. Experment 1 demonstrated that experience with escapable shock 4 hr after a session of inescapable tail shock completely reverses the analgesic response that is normally observed 24 hr later upon reexposure to shock. The escapability of the shock was shown to be the important factor in reversing the analgesic reaction, since subjects given inescapable shock in amounts equivalent to escape subjects exhibited no reduction in analgesia. Experiment 2 showed that experience with escapable shock 4 hr prior to a session of inescapable tail shock could also completely eliminate the long-term analgesic reaction. Experiment 3 replicated the results of Experiment 2, but employed a different escape task and temporal parameters in order to extend the generality of the findings, and to more closely match the procedures employed in behavioral experiments reported by J. L. Williams and S. F. Maier (Journal of Experimental Psychology: Animal Behavior Processes, 1977, 3, 240–253). The implications of these results for the areas of pain control and learned helplessness were discussed.     

Vicariously and directly learned helplessness and effectiveness1

Experiment 1 demonstrated the typical helplessness effect of inescapability on directly participating female subjects. Predictions drawn from social learning theory and comparison level theory on vicariously learned helplessness and effectiveness were then tested in a second study employing the prototypical learned helplessness induction design. In Experiment 2, 180 women served as either observers or direct participants and were pretreated as dyads with escapable, inescapable, or irrelevant noise. Consistent with social learning theory, subsequent instrumental task performance demonstrated facilitation effects of escapability on observers, and the same effect on direct participants also was found. No debilitation effects of vicariously or directly experienced inescapability were obtained. The combined results suggest that the induction of helplessness and effectiveness may depend on the social context in which relative controllability is operative, and are discussed primarily in terms of possible coaction effects.     

Acquisition of a free-operant-appetitive response in pigeons as a function of prior experience with response-independent food

Deficits in learning to escape from electric shock following exposure to response-independent preshocks have frequently been reported and have been referred to as learned helplessness. Experiments were conducted in order to determine whether a phenomenon similar to learned helplessness could be induced in appetitive free-operant procedures with pigeons. Subjects received preliminary training under one of the following conditions; protracted exposure to response-dependent grain presentations (key pecking), protracted exposure to response-independent grain deliveries, or short-term hopper training. Subjects were then tested for acquisition of a treadle-pressing response which was the only means of access to grain in the experimental chamber. The acquisition of the treadle-pressing response was retarded following protracted exposure to response-independent grain deliveries and the degree of this retardation was related to the complexity of the response-reinforcer contingency.     

Opiate antagonists and long-term analgesic reaction induced by inescapable shock in rats

Five experiments examined the influence of opiate antagonists on both the short-term analgesic reaction resulting 30 min after exposure to inescapable shock and the long-term analgesic reaction resulting after reexposure to shock 24 hr after inescapable shock exposure. Experiment 1 showed that the long-term analgesic reaction could be reduced by administration of naltrexone prior to exposure to inescapable tail shock. Experiment 2 showed that the reduction in the long-term analgesic reaction produced by naltrexone was dose-dependent. Experiment 3 showed that the long-term analgesic reaction could also be reduced by administration of naltrexone prior to reexposure to shock. Experiment 4 showed that the long-term analgesic reaction could be reduced by administration of large dose of naloxone prior to reexposure to shock. Experiment 5 showed that the short-term analgesic reaction was reduced by naltrexone administered prior to inescapable shock. Some implications of these results for the biochemical substrates of both learned helplessness and stress-induced analgesia are discussed.     

General Learned Irrelevance and Its Prevention

Random presentation of a tone and an electric shock to rats interfered with subsequent acquisition of a light–shock association. This interference, or “general learned irrelevance” phenomenon, however, could be prevented by prior learning of a positive relationship between the tone and the shock or that between a noise and the shock. These results strongly support the ideas that animals learn irrelevant stimulus relationships and that prior experience of stimulus relevance prevents learning irrelevance. The similarity of this observed prevention effect to an immunization effect on learned helplessness phenomena is discussed.     

Immunization against learned helplessness in the cockroach (Periplaneta americana)

Cockroaches exposed to one day of escapable shock prior to three days of inescapable shock did not become helpless on a shuttlebox-escape task. Like dogs and rats, cockroaches are immunized against learned helplessness by prior experience with escapable shock.     

Learned helplessness in the rat: time course, immunization, and reversibility.

Rats, like dogs, fail to escape following exposure to inescapable shock. This failure to escape does not dissipate in time; rats fail to escape 5 min, 1 hr., 4 hr., 24 hr., and 1 wk. after receiving inescapable shock. Rats that first learned to jump up to escape were not retarded later at bar pressing to escape following inescapable shock. Failure to escape can be broken up by forcibly exposing the rat to an escape contingency. Therefore, the effects of inescapable shock in the rat parallel learned helplessness effects in the dog.     

Learned helplessness or learned inactivity after inescapable stress? Interpretation depends on coping styles

Researches on uncontrollable events in the post-soviet states are overviewed. In our research, susceptibility to learned helplessness is studied in rats with active (KHA strain) versus passive (KLA strain) coping styles. Inescapable footshocks, butnot escapable footshocks, applied to KHA rats induced escape failures, diminished locomotion and coping, reduced measures of anxiety, and resulted in dexamethasone nonsuppression of the brain-hypothalamus-pituitary-adrenal axis—all characteristic of learned helplessness. In contrast, KLA rats demonstrated the same responses upon exposure to both escapable and inescapable stresses. While learned helplessness occurred in KHA rats, it appears that KLA rats exposed to inescapable stress demonstrated learned inactivity based upon the nondifference between effects of escapable and inescapable shocks. Relationships between coping styles and social ranks are discussed. Our and other’s results with genetically selected strains suggest active coping in dominant and subordinate subjects, and passive coping in subdominant animals confirm the importance of coping style and its relation to health under stress.     

Learned Helplessness or Learned Inactivity after Inescapable Stress? Interpretation Depends on Coping Styles

Researches on uncontrollable events in the post-soviet states are overviewed. In our research, susceptibility to learned helplessness is studied in rats with active (KHA strain) versus passive (KLA strain) coping styles. Inescapable footshocks, but not escapable footshocks, applied to KHA rats induced escape failures, diminished locomotion and coping, reduced measures of anxiety, and resulted in dexamethasone nonsuppression of the brain-hypothalamus-pituitary-adrenal axis--all characteristic of learned helplessness. In contrast, KLA rats demonstrated the same responses upon exposure to both escapable and inescapable stresses. While learned helplessness occurred in KHA rats, it appears that KLA rats exposed to inescapable stress demonstrated learned inactivity based upon the nondifference between effects of escapable and inescapable shocks. Relationships between coping styles and social ranks are discussed. Our and other's results with genetically selected strains suggest active coping in dominant and subordinate subjects, and passive coping in subdominant animals confirm the importance of coping style and its relation to health under stress.     

Prior exposure to inescapable electric shock in rats affects extinction behavior after the successful acquisition of an escape response

In Expt 1, rats exposed to 64 inescapable electric shocks in a restrainer or merely restrained were later given either 0, 5, 15 or 30 escape/avoidance training trials with a two-way shuttlebox procedure that does not lead to interference with escape acquisition due to prior exposure to inescapable shock. After escape training all rats were given an escape/avoidance extinction procedure in which shock was inescapable. The rats which had received prior exposure to inescapable shock responded less often and with longer latencies in extinction than did the restrained rats. Experiment 2 demonstrated that this effect is caused by the inescapability of the initial shock treatment. These results were explained in terms of (a) associative interference which minimized the effect of shuttlebox escape training for the preshocked subjects, and (b) a stronger tendency to recognize the presence of an inescapable shock situation during extinction for the preshocked subjects. The relationship between these results and previous work demonstrating that exposure to the escape contingency mitigates the effects of inescapable shock exposure was also discussed.     

Stimulus perseveration in a water maze following exposure to controllable and uncontrollable shock

When placed in a water-filled maze, mice display a pronounced preference for the illuminated over the nonilluminated arm of the maze. Exposure to inescapable shock increased the time spent in the illuminated arm of the maze, and decreased the frequency of entries into the nonilluminated arm. When animals that had received shock entered the nonilluminated arm they exhibited more activity per second than nonstressed animals. Controllability over the stressor enhanced the preference for the illuminated arm; however, the contribution of this variable was dependent on the number of shock trials mice received. Following 180 escapable or inescapable shock presentations the preference for the illuminated arm was enhanced. The propensity to approach the illuminated arm declined following a greater number (360) of escapable shock trials, while the preference for the illuminated arm did not decline in mice that received inescapable shock. Both escapable and inescapable shock were also found to produce a transient disruption of discrimination performance in a task where animals were required to emit a contraprepared response (swim to dark), whereas these treatments were without effect on performance of the highly prepared response of approaching the illuminated arm. It is provisionally suggested that enhancement of the perseveration represents an innate response to stressful stimuli, but as animals learn mastery over the response contingencies, the persistence in adopting such a response strategy wanes. Moreover, despite the differential effects of escapable and inescapable shock on the perseverative tendency, discrimination accuracy may not be differentially affected by these treatments in a task where acquisition progresses quickly and where explicit cues are associated with the correct and incorrect arms of the maze.     

Modeling signal features of escape response: effects of cessation conditioning in "learned helplessness" paradigm

Six experiments examined the effects of signaling the termination of inescapable shock (cessation conditioning) or shock-free periods (backward conditioning) on later escape deficits in the learned helplessness paradigm, using rats (Sprague-Dawley and Bantin-Kingman). A cessation signal prevented later performance deficits when highly variable inescapable shock durations were used during pretreatment. The inclusion of short minimum intertrial intervals during pretreatment did not alter the benefits of cessation conditioning but eliminated the protection afforded by a safety signal. The beneficial effects of both cessation and backward signals were eliminated when a single stimulus signaled shock termination and a shock-free period. Finally, a combination of cessation and backward signals was found to be most effective in immunizing against the effects of subsequent unsignaled, inescapable shock on later escape performance. These data suggest that cessation conditioning may be crucial to the prophylactic action of an escape response.     

Exposure to inescapable shock produces both activity and associative deficits in the rat

Interference with shuttle-box escape learning following exposure to inescapable shock is often difficult to obtain in rats. The first experiment investigated the role of shock intensity during escape training in the apparent fragility of the effect. Experiment 1A demonstrated that the magnitude of the interference effect was systematically related to shock intensity during shuttle-box testing. At .6 mA, a robust effect was obtained, whereas at .8 mA and 1.0, little or no deficit in the escape performance of inescapably shocked rats was observed. Experiment 1B demonstrated that the deficit observed in Experiment 1A depended upon whether or not rats could control shock offset. Experiment 2 suggested that preshock may suppress activity and that higher shock levels may overcome this deficit. Experiment 3 tested this as the sole cause of the escape deficit by requiring an escape response which exceeded the level of activity readily elicited by a 1.0-mA shock in both restrained and preshocked rats. In such a task, preshocked rats performed more poorly than did restrained controls. These results are consistent with the possibility that inescapable shock may, in addition to reducing activity, produce an associative deficit. Experiment 4 more clearly demonstrated that inescapable shock produces deficits in performance which cannot be expleined by activity deficits and which appear to be associative in nature. It was shown that inescapable shock interfered with the acquisition of signaled punishment suppression but not CER suppression. The theoretical implications of these data for explanations of the manner in which prior exposure to inescapable shock interferes with escape learning were discussed.