Underpredicted pain disrupts more than correctly predicted pain, but does not hurt more

One of the explanations for the negative effects of underpredicted aversive experiences is that they have more impact than correctly predicted aversive experiences. In a laboratory experiment 40 normal female subjects executed an auditory discrimination task. Subjects were randomly assigned to a correct information condition and an underprediction information condition. After ten trials (baseline) subjects were informed that they would receive some painful (correct prediction) or non-painful tingling (underprediction) stimuli during the discrimination task. Starting just before five of the following 20 discrimination trials, 2 s of painful electrical stimulation was given. Subjects rated sensations and painfulness of the electrical stimulation, subjective anxiety, and degree of distraction from the task, after each pain stimulus. Reaction times of the discrimination task and heart rate were measured. Underprediction information resulted in lower pain ratings, but stronger heart rate responses and higher disruption on the discrimination task, compared to correct information. This suggests that while underpredictions of pain do not hurt more, disruption on primary tasks and physiological impact are higher. Underpredicted pain has more impact than correctly predicted pain, not because it hurts more, but because it conveys inherent danger information.     

Effects of attentional focusing on pain perception

Two experiments were conducted to examine the hypothesized differential effectiveness of two attentional focusing strategies in pain perception. In the first experiment, subjects (72 male college students) rated their levels of pain after being exposed to either low- or high-intensity pressure stimulation for 75 s. Subjects were instructed to use either an external or internal focus of attention during the pain induction. Results revealed that external focusing was more effective for coping than internal focusing across both levels of stimulus intensity. The second experiment was a replication of the first, and featured bolstered internal focusing and stimulus intensity manipulations. Results showed that high-intensity stimulation produced higher pain ratings than did low-intensity stimulation for subjects in the internal focusing conditions, but not for those in the external focusing conditions. The findings support the power of distraction strategies for dealing with short-term pain with a rapid onset. Theoretical implications are discussed.The authors thank Darwyn E. Linder and Daniel M. Landers for their help in development of this research. The authors are also indebted to Sarah Colley, Jona Davis, Nanci Neuberger, and Rebecca Roberts for their assistance in data collection.     

Anticipatory threat and physical danger trait anxiety: A signal-detection analysis of effects on autonomic responding

The method of Signal-Detection Theory (SDT) was applied to the analysis of autonomic data in two experiments. In the first, apprehension surrounding the administration of loud tones was induced through preliminary information; in the second, it was increased by selecting subjects scoring high on a physical-danger trait anxiety scale. Despite enhanced autonomic reactivity, those in the first study who were led to believe that the tones would be extremely disturbing subsequently rated them as less disturbing than did their counterparts who were given comparatively benign expectations. The signal-detection analysis of heart rate and skin conductance suggested enhanced “preparedness of response” among the high-threat subjects; given the diminished subjective ratings, increased response readiness at the autonomic level may have reflected physiological activity assuaging subjective aversiveness of the tones. Contrary to the first study, the psychometrically designated threatened group in the second experiment produced both greater autonomic reactivity along with elevated subjective ratings of disturbance. The SDT analysis provided evidence of greater autonomic sensitivity to noxious stimulus properties. Results were discussed in terms of their implications for theories of anxiety; the comparative utilites of signal-detection theory and conventional methods of autonomic-response scoring were elaborated.     

Effects of instructional set on attributions of nonvolition during hypnotic and nonhypnotic analgesia

Fifty highly hypnotizable subjects were assigned to four treatment groups or a no-treatment control group and then underwent two pain stimulation trials. Half the treated subjects were administered hypnotic analgesia, half waking analgesia. Within hypnotic and nonhypnotic treatments, half the subjects were given actively worded analgesia instructions, half passively worded instructions. Subjects in the four treated groups reported equivalent pain reduction and equivalent use of coping imagery, although hypnotic subjects rated themselves as more deeply hypnotized than did nonhypnotic subjects. Both hypnotic and nonhypnotic subjects given passive instructions rated their pain reduction as occurring involuntarily, whereas those given active instructions reported that their pain was reduced through their active use of coping strategies. These findings support sociocognitive formulations of hypnotic responding that view ratings of involuntariness as reflecting contextually guided interpretations of behavior.     

无意识信息的刺激表征及其时间特性

无意识信息是否存在刺激表征有待解决。实验采用字母Flanker任务, 通过目标和flanker在刺激水平和反应水平上的冲突效应, 重点考察阈下flanker在刺激水平的表征。在相同的实验设计下, flanker可觉察时(实验1A), 观察到经典的刺激冲突效应和反应冲突效应; 而flanker无意识时(实验1B), 重复了反应冲突效应, 却观察到刺激冲突效应发生反转, 提示了无意识信息的反应加工及刺激加工。实验2采用符号材料促使刺激−反应的自动联结, 减少刺激−反应规则的难度, 结果重复了实验1B的发现--无意识信息引起反转的刺激冲突。刺激冲突下反转效应的一致结果表明无意识信息的刺激表征影响了认知加工。实验3考察这种影响在时间进程上的特点。无意识刺激表征的影响随反应时变化：在快速反应中观察到刺激冲突效应, 之后该效应发生反转且反转量随反应时增加而增大。相反, 无意识反应表征的影响在不同反应时下保持稳定。以上结果提供了无意识信息存在刺激表征的行为学证据并揭示了其时间特性, 提供了无意识领域中不一致研究结果的整合思路。     

Combining experiences over time: the effects of duration,intensity changes and on-line measurements on retrospective pain evaluations

Two experiments were conducted to examine the effects of various factors on retrospective pain evaluation. The factors examined in Experiment 1 were the rate and pattern of change, the intensity (particularly the final intensity), and the duration of the painful experience. Experiment 2 manipulated these factors and, in addition, examined the effect of continuous (on-line) ratings on the overall retrospective evaluation. The two experiments utilized different pain modalities, heat in the first and mechanical pressure in the second. In addition, all subjects in Experiment 1 experienced stimuli with the same physical magnitude, while in Experiment 2 stimuli were individually tailored to make them subjectively equivalent. In both experiments, subjects were presented with a series of painful stimuli and evaluated the intensity of each stimulus immediately upon its termination. The stimuli themselves were composed of multiple intensity levels that differentially changed over time (Intensity-Patterns). Subjects' on-line ratings in Experiment 2 closely mirrored the physical patterns of the intensities. The main conclusion from both experiments is that the retrospective evaluations of painful experiences are influenced primarily by a combination of the final pain intensity and the intensity trend during the latter half of the experience. In addition, results indicated that duration has little impact on retrospective evaluations for stimuli of relatively constant intensity. However, when the stimulus intensity changes over time, duration does play a role. Finally, the task of continuously reporting the stimulus intensity had a moderating impact on the retrospective evaluations. © 1998 John Wiley & Sons, Ltd.     

The ambiguous-cue problem: The effects of reduced similarity between trials and the schedule of reinforcement

In a series of seven experiments pigeons were trained on the two-choice ambiguous-cue problem that contains PA and NA trials. On PA trials choice of P (the positive stimulus) was reinforced and choice of A (the so-called ambiguous stimulus) was not reinforced; on NA trials choice of A was reinforced and choice of N (the negative stimulus) was not reinforced. When the two types of trials were distinguished by only the presence of P or N and each trial was terminated by one response, subjects quickly attained high levels of performance on NA trials but showed only chance levels of performance on PA trials. PA performance was markedly improved when a variety of additional stimuli distinguished the two types of trials and when a variety of schedules of intermittent reinforcement were employed; these manipulations had little effect on NA performance.     

A novel radiant heat test for assessing pain threshold in human subjects: Measurement stability

New methodologies to assess analgesic response in humans are needed to better integrate preclinical and clinical data. In the present study we examined the test-retest stability of an innovative radiant heat methodology compared with an electrical stimulation methodology. For the radiant heat task, a modified rodent tail flick apparatus was used. The latency for finger withdrawal was recorded. For the electrical stimulation tasks, subjects placed two fingers on two electrodes from which they received a brief series of increasingly intense electrical stimulations. Maximum stimulus intensity (in milliamps) delivered was recorded. On each of 4 test days, the subjects received five test trials with a 10-min interval between trials. All the subjects were tested twice on each apparatus in a counterbalanced design. Finger withdrawal latencies for the radiant heat task did not differ significantly across test trials or test days. Finger withdrawal scores for electrical stimulation increased significantly across test trials as well as test days. These data show that the radiant heat method generates consistent latencies across trials and days, whereas shock produces trends over time. The radiant heat task, which is convenient to operate and inexpensive to build, appears promising as a reliable test of pain threshold in humans.     

Development of conditional and equivalence relations without differential consequences

Two experiments were conducted to establish conditional stimulus relations without differential consequences and to test for the emergence of other relations. In Experiment 1, 3 adults responded to match-to-sample displays in which sample-comparison pairs were constant while the second comparison presented with each pair changed periodically across trials. No differential consequences followed any comparison selections. All subjects learned conditional relations between constant samples and comparisons, but results of tests for transitivity in those relations were equivocal. In Experiment 2, 4 children were given unreinforced training and testing similar to that provided to the adults in Experiment 1, with procedural refinements. One child learned conditional relations and demonstrated emergent relations that confirmed the development of two four-member equivalence classes. Another child learned the conditional relations but did not demonstrate any emergent relations reliably. A 3rd child, after reinforced training on two conditional relations, learned four new conditional relations without differential consequences and demonstrated symmetry but not equivalence in the trained relations. The 4th child did not learn the conditional relations. These findings emphasize the importance of careful construction of tests for stimulus equivalence and suggest a need for critical analyses of the apparent emergence of untrained stimulus relations on unreinforced tests that has been observed in several stimulus equivalence studies.     

ASSESSING AND PROGRAMMING GENERALIZED BEHAVIORAL REDUCTION ACROSS MULTIPLE STIMULUS PARAMETERS

Generalization across three stimulus parameters was examined for 5 individuals whose self-injurious behavior was maintained by escape from task demands. Prior to treatment, three stimulus parameters (therapist, setting, and demands) were systematically varied across baseline sessions. These variables were held constant during treatment, which consisted of escape extinction. When treatment was completed, three novel stimulus parameters were probed. If the rate of self-injury was high during this probe, treatment was reimplemented with one new stimulus parameter (the other two were the same as in the original treatment condition). Following this second treatment, another probe with three novel stimuli was conducted. If the rate of self-injury was again high, treatment was implemented again while a second stimulus parameter was changed. This sequence continued until generalization was observed across the three parameters. Results showed idiosyncratic differences in generalization. The behavior of 2 subjects showed complete generalization during the first novel probe. A 3rd subject's behavior showed generalization following treatment across two stimulus parameters (setting and therapist). The behavior of the 2 remaining subjects showed a complete lack of generalization across the three parameters; both subjects required training for novelty by randomly varying the stimulus parameters for a substantial number of sessions.     

Studies in observational paired-associate learning: Informational,social, and individual difference variables

Four experiments examined the relative importance of informational (proportion of correct responses and kinds of errors emitted by a model), social (model competency, sex of model, video vs. audio taped model), and individual difference (sex of subject, grade) variables in observational paired-associate learning. In Experiments I–III, vicarious subjects received cycles of study-model-test trials, while direct subjects were given the same sequences with intervening test or stimulus familiarization trials. In Experiment IV, vicarious subjects received cycles of study-test-model-test trials, while direct subjects received the cycles with a test trial replacing the model trial. No confirmation was provided on test and model trials. Whereas the effects attributable to social and individual difference variables were generally negligible, mere accuracy of the model's responses repeatedly covaried with performance on the last test trial of each cycle. Conditional analyses established that (1) vicarious facilitation is comparable across cycles and localized in items responded to incorrectly on immediately preceding test trials, and (2) observers learn fewer incorrect than correct model responses. Vicarious groups performed at reliably higher levels than direct subjects on model correct but not incorrect items. The results strongly suggest a close correspondence between direct and vicarious verbal learning principles and mechanisms.     

Temporal invariance for picture-word translation: Evidence from drawing-writing and naming-reading tasks

In two experiments, picture-word processing was investigated using graphic (drawing-writing) and verbal (naming-reading) production tasks. In both experiments, the subjects drew a picture or wrote a word upon presentation of a picture or a word stimulus. Additionally, the subjects in Experiment 2 named a picture or read a word stimulus. Production onset latency was assessed. In both experiments, drawing production was initiated more slowly than was writing production. In Experiment 2, graphic production was initiated more slowly than was verbal production. Equivalent latency increases were found for cross-modality trials (e.g., drawing a picture given a word stimulus) relative to within-modality trials (e.g., drawing a picture given a picture stimulus), independent of stimulus modality (word or picture), production modality (word or picture), or task (graphic or verbal production). These results strongly support a mathematical model which incorporates temporal invariance for pictures and words concerning encoding, cross-modality transfer, and retrieval.     

The effects of trait label and order of presentation on observers' ratings of performance anxiety

In two experiments, the effects of different stimulus presentation orders and trait labels on observers' ratings of performance anxiety were examined. In Experiment 1, 60 college students viewed, in one session, ten 3-min videotapes of a man speaking while displaying a variety of the behavioral manifestations of anxiety. The tapes varied linearly in the percentage of time during which anxious behaviors were emitted. Anxiety ratings were made along either a “calm” or an “anxious” dimension. Subjects were randomly assigned to one of three orders of presentation conditions (with the frequencies of anxious behaviors ascending, descending, or randomized across tapes) and one of two trait-label conditions, calm or anxious. In Experiment 2, 60 additional subjects viewed these same tapes and a contrasting series designed to display a consistent rate of anxiety behaviors. These tapes were viewed in 10 sessions over a 2- to 5-week period. Results replicated prior studies showing that the order of presentation can significantly affect observers' ratings. Additionally, the results suggested that, under certain conditions, subjects may not perceive a conceptually dichotomous variable (e.g., calm vs. anxious) in the same way. These results are discussed in terms of the complexity of observer behavior and potential problems in comparing outcome studies that use dichotomous traits.     

Spontaneous configuring to a tone-light compound using appetitive training

Rats were trained to bar-press for water in the presence of a simultaneous compound tone-light stimulus using a discrete-trial procedure. Different groups were given between 300 and 3900 trials. When subsequently tested in extinction, all rats showed consistent levels of responding to the compound stimulus but responding to the tone and light components declined as a function of number of training trials. This is a demonstration of spontaneous configuring. Two other experiments showed that with similar procedures generalization from a component of the training stimulus to other values on the same continuum decreases with increased training with the compound stimulus. It was concluded that configuring and generalization from a single stimulus involve the same processes.     

TOO MUCH REINFORCEMENT,TOO LITTLE BEHAVIOR: ASSESSING TASK INTERSPERSAL PROCEDURES IN CONJUNCTION WITH DIFFERENT REINFORCEMENT SCHEDULES WITH AUTISTIC CHILDREN

Task interspersal procedures have been quite effective in increasing autistic children's motivation to learn. These procedures have typically demonstrated that the inclusion of reinforced maintenance tasks (previously learned tasks) increases responding to new acquisition tasks because more reinforcers, in general, are available. However, studies have not specifically addressed the effects of various schedules of reinforcement, used in conjunction with task interspersal procedures, upon response acquisition. In the present study, a multiple baseline design across subjects was used to assess different reinforcement schedules. Five autistic children participated in learning sessions, during which trials of an acquisition task were interspersed with trials of three maintenance tasks. Correct responses to acquisition tasks were continuously reinforced throughout all conditions, while the reinforcement schedule for competent performance of maintenance tasks differed systematically. Results indicated that all children learned the new tasks when food reinforcers were presented only for acquisition tasks. Results are discussed in terms of behavioral contrast and improving the effectiveness of motivation-enhancing procedures for autistic children.     

Disruption of a temporal discrimination under response-independent shock

The responding of rats was reinforced on one key after a 1-sec auditory stimulus and on a second key after a 5-sec stimulus. With errors punished by a short timeout, all subjects achieved a high level of accuracy. A chain of responses during the stimuli mediated the performance so that when the auditory signals were omitted accuracy decreased only slightly. Response-independent aversive stimulation superimposed upon this procedure both suppressed the total amount of behavior and reduced the accuracy of the discriminative performance, the intensity of the stimulus determining the error rate. The increase in errors under these conditions may have depended in part upon differential suppression of members of the response chain, but such suppression was not necessary, since error rate increased even in its absence. Furthermore, the locus of response disruption within the chain was not consistent from day to day either for any individual animal or across animals.     

Suffering for science: the effects of implicit social demands on response to experimentally induced pain

In two experiments subjects rated their pain during baseline trials of cold pressor and finger pressure pain. After various instructional treatments, they were posttested with these same stimuli. As in previous studies, we found in both experiments that coping suggestions significantly reduced reported pain. Experiment 1, however, demonstrated that subjects often refrained from using available cognitive coping strategies to reduce pain unless they had been given explicit permission to do so. Experiment 2 replicated this finding and also showed that explicit permission to "do whatever you can to reduce pain" was as effective as a coping suggestion in decreasing reported pain. These findings indicate that subjects' interpretation of what is appropriate responding in the test situation determines how they choose to cope with the painful stimulation. Thus standard experimental procedures for assessing baseline levels of pain implicitly lead subjects to refrain from coping and thereby tend to underestimate their ability to control pain. Moreover, suggestions and other instructional techniques for coping with pain may produce much of their effect not by teaching subjects new coping skills but instead by giving them permission to use already available coping strategies.     

Size invariance in curve tracing

Subjects decided whether two dots were on the same curve or on different curves in patterns consisting of two curves and two dots in displays that had an exposure duration of 200 msec or that remained in view until the subjects' response. The overall size of the patterns was varied by a factor of two. Furthermore, across experiments, we manipulated the predictability of the size of the pattern on a particular trial. On half of the trials, the two dots were on the same curve; across these trials, the distance between the dots, along the curve, was manipulated systematically while the Euclidean distance between the dots was held constant. On the other half of the trials, the two dots were on different curves. The time to respond same increased monotonically as curve distance between the dots increased, suggesting that subjects mentally traced the curve in order to perform the task. The absolute size of the pattern had little or no effect on the response times, indicating that it was curve distance relative to the overall pattern size, rather than absolute distance, that controlled response times. Furthermore, expectancies about pattern size had essentially no effect on performance. Taken together, the results suggest that the rate of tracing is determined by various stimulus properties that covary with the overall size of the pattern on which tracing takes place, such as the distance between the traced curve and nearby distractor curves, or the curvature of the traced curve.     

Satiation, capacity, and within-session responding

Responding may change substantially over the course of a session (McSweeney, Hinson, & Cannon, 1996). The role of satiation in this effect was investigated in three experiments. Experiment 1 showed that the capacity of pigeons to consume milo over a 1-hr period was relatively stable across three different methods of measurement. In Experiment 2, pigeons were divided into two groups that differed in their capacity based on one of those measures. Key pecking was then reinforced under a variable-interval 30-s schedule with hopper durations of 2 or 5 s. According to the satiation hypothesis, subjects with small capacities should satiate faster and therefore show greater decreases in food-reinforced responding than would subjects with larger capacities. The results confirmed this prediction and showed that the magnitudes of within-session decreases were better predicted by the amount an animal consumed relative to its capacity than by absolute amount alone. In Experiment 3, each pigeon was prefed 0, 5, 15, or 25 g of milo prior to each session. Consistent with the satiation hypothesis, increases in prefeeding produced lower overall response rates in the smaller capacity subjects than in the larger capacity subjects at each level of prefeeding. These experiments demonstrate the importance of a new variable in the control of behavior, and provide a recommended technique for its measurement.     

Timeout postponement without increased reinforcement frequency

Three experiments were conducted to examine pigeons' postponement of signaled extinction periods (timeouts) from a schedule of food reinforcement when such responding neither decreased overall timeout frequency nor increased the overall frequency of food reinforcement. A discrete-trial procedure was used in which a response during the first 5 s of a trial postponed an otherwise immediate 60-s timeout to a later part of that same trial but had no effect on whether the timeout occurred. During time-in periods, responses on a second key produced food according to a random-interval 20-s schedule. In Experiment 1, the response-timeout interval was 45 s under postponement conditions and 0 s under extinction conditions (responses were ineffective in postponing timeouts). The percentage of trials with a response was consistently high when the timeout-postponement contingency was in effect and decreased to low levels when it was discontinued under extinction conditions. In Experiment 2, the response-timeout interval was also 45 s but postponement responses increased the duration of the timeout, which varied from 60 s to 105 s across conditions. Postponement responding was maintained, generally at high levels, at all timeout durations, despite sometimes large decreases in the overall frequency of food reinforcement. In Experiment 3, timeout duration was held constant at 60 s while the response-timeout interval was varied systematically across conditions from 0 s to 45 s. Postponement responding was maintained under all conditions in which the response-timeout interval exceeded 0 s (the timeout interval in the absence of a response). In some conditions of Experiment 3, which were designed to control for the immediacy of food reinforcement and food-correlated (time-in) stimuli, responding postponed timeout but the timeout was delayed whether a response occurred or not. Responding was maintained for 2 of 3 subjects, suggesting that behavior was negatively reinforced by timeout postponement rather than positively reinforced by the more immediate presentation of food or food-correlated (time-in) stimuli.