Controlling pain reports through operant conditioning: a laboratory demonstration

Operant conditioning of pain reports was studied in two laboratory experiments. In the first one 5 subjects were given the same pain stimulus on 15 trials and their recorded pain ratings gave no systemic trends across subjects. 8 other subjects received the same pain tests but on some of the trials increases or decreases in pain ratings were verbally reinforced while the noxious stimulus was held constant across trials. Clear and significant differences between reinforced increases and decreases in pain reports were observed. In Exp. 2, 5 subjects were given neutral feedback and systematically decreasing levels of noxious stimulation, resulting in a good correlation between pain ratings and stimulation level. 5 subjects were provided reinforcement for increasing pain reports while the pain stimulus was systematically reduced. Increases in pain reports were observed simultaneously with large decreases in the level of the noxious stimulus. Results of these experiments support the operant conception of pain.     

Reactivity and response to pain

Male and female volunteers (N = 144) answered the Reactivity Scale (RS) and underwent testing for their perceived intensity and tolerance for finger-pressure pain. Half the Ss were randomly assigned to a low-intensity treatment (1150 g) and half to a high-intensity treatment (2300 g). Pain was rated at 30 and 60 sec., and Ss were asked to endure it as long as possible up to 5 min. The major findings were as follows: (1) women outscored men on reactivity; (2) the three pain measures intercorrelated highly; (3) high-intensity stimulation produced higher pain ratings and shorter tolerance than did low-intensity stimulation; (4) men gave lower intensity ratings than women and tolerated the pain longer; (5) reactivity related positively to judged pain at 30 and 60 sec, and negatively to pain tolerance; (6) there were no significant interaction effects among stimulus intensity, sex and reactivity for any pain measure; (7) the variance in the pain measures accounted for by stimulus intensity, sex and reactivity ranged from 26 to 32%. The implications were briefly discussed for the validity of the RS and factors explaining responses to experimentally-induced pain.     

The effects of vicarious experience and stimulus intensity on pain termination and work avoidance

The purpose of the present investigation was to evaluate the role of vicarious experience in the acquisition of pain termination and work avoidance. Fifty-six experimental subjects were randomly assigned to view a film of a model who either terminated exposure to a pain stimulus and work task after 10 sec (high-avoidant) or 70 sec (low-avoidant). Following the film presentation, subjects were exposed to the pain stimulus and work task. Half of the subjects were randomly chosen to perform the task with a low-intensity pain stimulus (LP) and the other half performed the task while exposed to a high-intensity pain stimulus (HP). The results indicated that subjects in the high-avoidant model conditions (HA) did significantly less work and tolerated the pain stimulus for significantly fewer seconds compared to the low-avoidant model groups (LA). Subjects in the LP groups tolerated the pain stimulus significantly longer and did significantly more work compared to subjects in the HP groups. No significant interaction was observed. The results provide support for the hypothesis that behavioral reactions to pain can be acquired by vicarious experience. Implications for future research are discussed.     

Effects of a stimulus associated with a victim's pain on later aggression.

Male college students participated in an experiment designed to associate a neutral stimulus with a victim's pain and then to assess the impact of the paired stimulus on their aggression. The subjects were either provoked or not provoked by a confederate's shock evaluation. They then observed a flashing white light that was associated with either their former evaluator's pain or an irrelevant, affectively neutral event. The subjects then administered electric shocks to a different confederate, with whom they had not interacted previously, at the flash of both the familiar white light (the conditioned stimulus) and a novel blue light. Results supported the prediction that provoked subjects would give more intense shocks to the conditioned stimulus when it had been associated with their evaluator's pain. Unprovoked subjects were found to give less intense shocks to the light that had been associated with their evaluator's pain.     

Avoidance of pain of unpredictable intensity

Unpredictability of the intensity of an aversive event might be an important factor in producing negative effects of the event, especially if the UCS becomes stronger than could have been expected. The present experiment tested the hypothesis that unpredictability of intensity of a painful stimulus contributes to avoidance behaviour. The experiment was concealed in a shock working-up procedure, which was done to assess the pain level subjects were willing to tolerate in a subsequent experiment. The experimental subjects, who received an unannounced sudden increase of the pain stimulus during the working-up procedure, tolerated less pain on a subjective as well as on an objective level (avoidance of high levels of pain) than the control subjects, who received the stimuli in a predictable pattern. The results support the hypothesis that unpredictability of intensity of an aversive event contributes to avoidance behaviour.     

The Effect of External and Internal Focus of Attention on Gait Variability in Older Adults

Internal focus of attention on a movement or focusing on an external target are both strategies that can affect motor performance. The authors explored whether manipulating subjects' focus of attention while walking would alter gait variability, a measure reflecting consistency of gait and associated with the risk of falling in older adults. Twenty community-living older adults participated in the study and were tested while focusing their attention on (a) gait consistency (internal focus) or (b) metronome beats (external focus). In both conditions gait variability increased (i.e., worsened p < .05) or did not change. No benefit was found in instructing subjects to focus on gait consistency or metronome beats. Such instructions may actually have distracted and interfered with the execution of gait.     

Index to Volume 117

In some individuals, noise appears to have an adverse effect on memory recall. This decrement may result from a shift in the memory strategy being employed. Studies have shown memory strategies used by persons with an internal locus of control differ from those used by persons with an external locus of control. The present investigation asked subjects who were classified as either internal or external in locus of control to recall words presented under conditions of noise and of quiet. Word recall was aided by providing subjects with potential memory strategies. Each word list included words from meaningful content categories (which favor a semantic strategy) and word pairs that rhymed (which favor a perceptual strategy). Though internal and external subjects did not differ in total words recalled, they did differ in their use of strategies. Whereas internal subjects' strategies were unaffected by noise, external subjects decreased their use of the higher level semantic memory strategy (content categories) and increased their use of lower level perpetual (rhymes) strategy in the noise condition. The results are discussed in terms of a differential arousal hypothesis.     

Painfulness decreases the discriminability of electric shock

Two experiments were designed to investigate the relation between the reported painfulness and the discriminability of pairs of electric shocks for which the ratio between the higher and the lower intensity was held constant. In both experiments, subjects first gave category ratings of the painfulness of single shocks in the range 40 to 4.8 mA. Then, in a discrimination experiment, they were required to identify the stronger of a pair of intensities presented in succession. The proportion of correct responses (Experiment 1) or the proportion of area under the receiver operating characteristic (Experiment 2) increased between a low-intensity pairing and a medium-intensity pairing and decreased between a medium-intensity pairing and a high-intensity pairing for subjects who rated the highest intensities as strongly painful. Subjects who gave moderate- or weak-pain ratings for the high-intensity shocks showed no significant increase or decrease in accuracy between the medium- and high-intensity pairings. Time-order errors were observed in Experiment 1. The proportion of trials on which the second stimulus of the pair was identified as the stronger increased monotonically as a function of stimulus magnitude. The results are discussed in the context of psychological assessment of analgesic procedures.     

Dynamic processes in emotion regulation choice

ABSTRACT

Because emotion regulation (ER) processes operate over time, they potentially change the context in which subsequent ER processes occur. To test this proposal, fifty-two healthy participants completed the ER choice task. Thirty standardized low- and high-intensity negative images were used to generate different emotional contexts in which participants selected between distraction or reappraisal strategies to decrease the intensity of their negative emotion. Participants then implemented their selected strategy and rated their negative emotion. Using a dynamic perspective, we examined as predictors of ER strategy choice, in addition to current stimulus intensity, several contextual factors from the immediately preceding trial: preceding stimulus intensity and strategy choice, and the intensity of negative affect following the previous strategy implementation and thus preceding the current trial. Results replicated earlier findings that participants are more likely to choose distraction for high-intensity images. Extending earlier findings, selecting reappraisal in the preceding trial and greater negative affect preceding the current trial were associated with lower odds of choosing distraction. The lack of significant interactions among the current and preceding trial factors suggests that these effects on ER choice were direct and not through moderating the effect of current stimulus intensity. These findings support dynamic theories of ER.     

‘Random’ saccadic eye movements during verbal-linguistic and visual-imaginal tasks

Previous research has suggested that questions eliciting visual imagery are associated with lower rates of saccadic eye movements as compared to questions eliciting verbal processes. Two experiments reported here examined the roles of external visual stimulation and speech output in this effect. In both experiments, questions designed to elicit verbal-linguistic or visual-imaginal processing, and which required either syntactically complex or simple responses, were administered while eye movements were recorded by electrooculography. In experiment 1, 42 subjects responded while viewing either the interviewer's face or a gray oval on a video monitor. Imaginal questions elicited a lower rate of eye movements than did verbal questions regardless of the display on the monitor. In experiment 2, 17 subjects responded in conditions of light and darkness. Imaginal questions elicited lower rates of eye movements in both light and dark. Neither cognitive mode nor speech output requirements interacted with stimulus conditions in either experiment. The failure of visual conditions to influence the verbal-imaginal difference in eye movement rate is viewed as inconsistent with a visual interference interpretation of the relationship of eye movements to cognitive activity. Alternate interpretations are discussed.     

Effects of preparatory information about sensations, threat of pain, and attention on cold pressor distress.

Pain experience is conceptualized as a combination of stimulus sensations (e.g., aching) and emotional distress. In Experiment 1, less distress was reported to cold pressor stimulation by subjects first told about stimulus sensations than by subjects who were uninformed or were told about symptoms of bodily arousal (e.g., tension). Adding a pain warning to sensation information blocked distress reduction, presumably by eliciting an emotional interpretation of the stimulus. In Experiment 2, subjects attending only to hand sensations reported less distress than subjects attending to their bodies. This decrease in the power of the stimulus to provoke emotion is presumably mediated by a schema of hand sensations formed by attention. In Experiment 3, subjects attending to hand sensations early in the immersion and distracting themselves later reported the same low levels of distress as did subjects who attended to hand sensations throughout. Subjects distracted throughout and subjects attending to hand sensations later showed no distress reduction. Therefore, stimulus schematization must precede distress reduction. Implications for distress control are discussed.     

The Effect of Anxiety Sensitivity and Gender on the Experience of Pain

The association between negative affectivity (NA) and health complaints is thought to reflect a stronger attentional focus on bodily sensations in high NA persons. Perceiving these sensations as rather threatening, high NA persons may scan their internal environment for impending signs of pain and trouble. Using an on-line registration of attentional deployment, we tested whether high NA persons were allocating more attentional resources to internal sensations and less to external stimuli compared to low NA persons. High and low NA participants (N = 68) performed a Stroop-like primary task during a number of trials in which: (1) only an internal; (2) only an external; or (3) both an internal and an external stimulus could occur. Internal stimuli consisted of 7.5% carbon dioxide administrations, causing slight increases in ventilation. An increase in time interval between successive tones served as the external stimulus. Participants were asked to press a button when they noticed one of both events. Results showed that high NA participants: (1) detected the effects of a first respiratory stimulus faster; (2) performed poorer on the tone task when anticipating a respiratory challenge; (3) performed slower on the Stroop task during respiratory stimuli. These findings may indicate that high NA participants show a stronger attentional bias to internal sensations.     

Perceived self-efficacy in coping with cognitive stressors and opioid activation

This experiment tested the hypothesis that perceived self-inefficacy in exercising control over cognitive stressors activates endogenous opioid systems. Subjects performed mathematical operations under conditions in which they could exercise full control over the cognitive task demands or in which the cognitive demands strained or exceeded their cognitive capabilities. Subjects with induced high perceived self-efficacy exhibited little stress, whereas those with induced low perceived self-efficacy experienced a high level of stress and autonomic arousal. Subjects were then administered either an inert saline solution or naloxone, an opiate antagonist that blocks the analgesic effects of endogenous opiates, whereupon their level of pain tolerance was measured. The self-efficacious nonstressed subjects gave no evidence of opioid activation. The self-inefficacious stressed subjects were able to withstand increasing amounts of pain stimulation under saline conditions. However, when endogenous opioid mechanisms that control pain were blocked by naloxone, the subjects were unable to bear much pain stimulation. This pattern of changes suggests that the stress-induced analgesia found under the saline condition was mediated by endogenous opioid mechanisms and counteracted by the opiate antagonist.     

LOUDNESS AS A FUNCTION OF THE DURATION OF AUDITORY STIMULATION

The perceived loudness of a 1000 c/s tone was measured by a direct scaling method under different conditions of intensity (19–35 db) and duration (50–500 msec) of stimulation. It was found that loudness grows as a logarithmic function of stimulus duration; the relation was verified for ten individual subjects and four levels of intensity. In addition, the relation between temporal threshold and level of intensity was tentatively described.     

Immediate and delayed effects of victim suffering on the attacker's aggression

On the first day of a two-day experiment, male undergraduates were either angered or not, and they were given either high, low, or no metered pain feedback after each shock they supposedly delivered to their previous evaluator for his errors on a learning task. After the learning task the subjects made a number of ratings, including how much they had enjoyed this first session. On the second day, all subjects were simply required to administer shocks to a different person for his mistakes on the same learning task. The angered subjects were more punitive on both days toward both learners than the nonangered men. On the first day the angered men also increased the intensity of the shocks they delivered over trial blocks. Most interestingly, the angered men showed more enjoyment of the first session of the experiment as their victim's pain increased, and this enjoyment rating was related to the angered subjects' level of aggression on the second day of the experiment when they punished an “innocent” victim. The results were interpreted as consistent with the hypothesized reinforcement process which essentially states that signs and/or knowledge of the victim's suffering can reinforce impulsive or angry aggressive behavior.     

The Effect of Attention Allocation Instructions on Self-paced Task Performance under Quiet and Distracted Conditions

This study examined the effectiveness of external and internal focusing attention instructions on the performance of three throwing tasks under both quiet and distracted conditions. The main finding was that during acquisition, the external focus of attention led to improved performance when compared to internal focus of attention and control, but only under quiet conditions. It was also found that during auditory and visual distraction conditions, both types of focus attention produced similar levels of performance, and both groups were superior to the control condition. It is suggested that sport psychology consultants provide their athletes with external focusing attention instructions.     

Conditioned placebo responses

Following earlier animal research, we attempt to condition placebo effects in human subjects. Four groups of 8 voluntary subjects were told that the experimenters would test a powerful new analgesic cream over three sessions by assessing its ability to reduce experimentally induced pain. The analgesic cream was, in fact, a placebo. In the first session all subjects were tested with and without the cream to assess their placebo response. In the second session, to condition two groups (with differing stimulation levels) to experience pain relief in response to the placebo, we repeatedly paired a reduction in nocioceptive stimulation with placebo administration. (Subjects were unaware that stimulation levels were manipulated). To condition the other two groups (with different stimulation levels) to experience an exacerbation of the pain, we paired an increase in nocioceptive stimulation with placebo administration. In the third session, all subjects were again tested for placebo response. Results suggested that placebo responses are conditionable in the laboratory in both a positive and negative direction. The clinical implications of a learning theory of placebo behavior are discussed.     

Top-down gain control in the auditory system: evidence from identification and discrimination experiments

The influence of intensity range in auditory identification and intensity discrimination experiments is well documented and is usually attributed to nonsensory factors. Recent studies, however, have suggested that the stimulus range effect might be sensory in origin. To test this notion, in one set of experiments, we had listeners identify the individual tones in a set. One baseline condition consisted of identifying four 1-kHz, low-intensity tones; the other consisted of identifying four 1-kHz, high-intensity tones. In the experimental conditions, these baseline tone sets were augmented by adding a fifth tone at either 1 or 5 kHz. Added 5-kHz tones had little effect on identification accuracy for the four baseline tones. When an added 1-kHz tone differed substantially in intensity from the four baseline tones, it adversely affected performance, with the addition of a high-intensity tone to a set of low-intensity tones having a more deleterious effect than the addition of a low-intensity tone to a set of high-intensity tones. These and further results, obtained in an exploration of this asymmetrical range effect in a third identification experiment and in two intensity-discrimination experiments, were consistent with the notion of a nonlinear amplifier under top-down control whose functions include protection against sensory overload from loud sounds. The identification data were well described by a signal-detection model using equal-variance Laplace distributions instead of the usual Gaussian distributions.     

Conditioned suppression of behavior maintained by intracranial stimulation as a function of stimulation intensity.

Conditioned suppression was demonstrated in two experiments with rats lever pressing on a fixed-ration 1 schedule for lateral hypothalamic intracranaial stimulation (ICS)'n Experiment I, conditioned suppression of responding for low-intensity ICS was obtained with a moderate intensity of foot shock, In Experiment II, low and high intensities of ICS were alternated within the same session and the same animal The suppression that was exhibited with low intensity ICS was minimal or absent with high-intensity stimulation, despite the pairing of foot shock with each warning stimulus. Conditioned suppression was a function of ICS intensity, and was independent of response rates. The inverse relationship between ICS intensity and degree os suppression is consistent with a motivational analysis of conditioned suppression. Previous reports of resistance to suppression of behaviors maintained by ICS may now be attributed to the use of high-intensity stimulation.