The reality of phantom limbs

This paper evaluates the joint influence of peripheral neurophysiological factors and higher-order cognitive and affective processes in triggering or modulating a variety of phantom limb experiences, including pain. Part 1 outlines one way in which the sympathetic nervous system may influence phantom limb pain. A model involving a sympathetic-efferent somatic-afferent cycle is presented to explain fluctuations in the intensity of sensations referred to the phantom limb. In part 2, the model is extended to explain the puzzling finding that onlyafter amputation are thoughts and feelings capable of evoking referred sensations to the (phantom) limb. While phantom pains and other sensations frequently are triggered by thoughts and feelings, there is no evidence that the painful or painless phantom limb is a symptom of a psychological disorder. In part 3, the concept of a pain “memory” is introduced and described with examples. The data show that pain experienced prior to amputation may persist in the form of a memory referred to the phantom limb causing continued suffering and distress. It is argued that two independent and potentially dissociable memory components underlie the unified experience of a pain memory. This conceptualization is evaluated in the context of the surgical arena, raising the possibility that under certain conditions postoperative pain may, in part, reflect the persistent central neural memory trace left by the surgical procedure. It is concluded that the experience of a phantom limb is determined by a complex interaction of inputs from the periphery and widespread regions of the brain subserving sensory, cognitive, and affective processes.     

The momentum of human behavior in a natural setting

Adults with mental retardation in a group home received popcorn or coffee reinforcers for sorting plastic dinnerware. In Part 1 of the experiment, reinforcers were dispensed according to a variable-interval 60-s schedule for sorting dinnerware of one color and according to a variable-interval 240-s schedule for sorting dinnerware of a different color in successive components of a multiple schedule. Sorting rates were similar in baseline, but when a video program was shown concurrently, sorting of dinnerware was more resistant to distraction when correlated with a higher rate of reinforcement. In Part 2 of the experiment, popcorn or coffee reinforcers were contingent upon sorting both colors of dinnerware according to variable-interval 60-s schedules, but additional reinforcers were given independently of sorting according to a variable-time 30-s schedule during one dinnerware-color component. Baseline sorting rate was lower but resistance to distraction by the video program was greater in the component with additional variable-time reinforcers. These results demonstrate that resistance to distraction depends on the rate of reinforcers obtained in the presence of component stimuli but is independent of baseline response rates and response–reinforcer contingencies. Moreover, these results are similar to those obtained in laboratory studies with pigeons, demonstrating that the determination of resistance to change by stimulus–reinforcer relations is not confined to controlled laboratory settings or unique to the pigeon.     

The redundancy of work alienation and job satisfaction: Some evidence of convergent and discriminant validity

The multitrait-multimethod matrix (MTMM) technique was used in an attempt to help clarify the ambiguities regarding concepts of work alienation, job satisfaction, and the relationships between them. Within each attitude domain considered separately, generally acceptable evidence of convergent and (to a lesser degree) discriminant validity was found for the trait measures (four dimensions of alienation and five of satisfaction). However, the discrimination between alienation and satisfaction measures was no greater than that among satisfaction and among alienation, casting doubt on the demarcation of these as two distinct domains. The measures of satisfaction and alienation also were not correlated differentially with demographic and self-esteem measures. Note was taken of the limitations in our knowledge and operationalization of these areas, as these relate to the assumptions of MTMM technique regarding independence of both underlying trait constructs and measurement methods.     

Prerequisite vs. in vivo acquisition of self-feeding skill

Separating the acquisition of prerequisite skills from the learning of skills in vivo may be a more efficacious procedure for self-help training of low functioning developmentally delayed children. Two procedures for training independent use of a fork at meals were compared using two equivalent groups of three subjects each, in multiple baseline design. Using previously accepted procedures, one group was trained during meals while the experimental group received prerequisite training making use of simulated food (styrofoam pieces). Data during training, generalization-to-meal, and follow-up were collected. For 6 months following training, the efficacy of prerequisite training was upheld. The complexity of individual responses to the singular or conjunctive use of social and edible reinforcement for the purpose of self-feeding skill generalization and maintenance, is discussed.     

Opportunity for thought as a mediator of attraction to a dissimilar stranger: A further test of an information seeking interpretation

It has previously been shown that confusion, produced by an ambiguous film, leads to increased attraction to attitudinally dissimilar others. It was posited that confusion leads to a search for information that will help to structure the confusing situation, and that dissimilar others have perspectives that are of value in this regard. In the present study, subjects were exposed to either a confusing film, a nonconfusing film preceded by an explanation designed to produce confusion, or the nonconfusing film with no preceding explanation. They then were either given an opportunity to think about the film's meaning or were deprived of this opportunity through a filler task. It was argued that the opportunity to think about the film would allow subjects to gain structure, and that this would reduce their confusion, decrease their need for more information, and thereby decrease their attraction to a dissimilar other. The results supported this contention. That is, subjects exposed to either the confusing film or the nonconfusing film with an explanation and then given an opportunity for thought showed significantly less attraction to a dissimilar stranger than their counterparts who were deprived of this opportunity.     

A test of the generality of the word-context effect

Three experiments tested the generality of the finding of Reicher (1969) and Wheeler (1970) that a word context facilitated the accuracy of recognition of an embedded target letter. In the present experiments, the context was a letter and the target was a letter fragment. The letter context greatly facilitated the recognition of the letter fragment. In Experiment I, this improvement was in many cases from chance level to perfect performance. An interpretation of this effect in terms of greater familiarity of the fragment and its context was disconfirmed in Experiment II. A procedure of preexposure cueing in Experiment III eliminated the superior recognizability of fragments having a letter context.     

Head restraint enhances visual monitoring performance

Subjects monitored a visual display for occasional increments in the horizontal movement of a bar of light. When the display was viewed without head restraint, detection probability was directly related to the amplitude of the increments in movement which constituted critical signals and inversely related to background event rate (the frequency of neutral events in which critical signals were embedded). When positioning of the head was restrained by a headrest, the detectability of low-amplitude signals was enhanced considerably and the influence of background event rate was attenuated. The results are considered as providing further support for the importance of sense mode coupling in visual monitoring.     

Varieties of frequency interference in children's recognition of sentence information

The memory of fourth-grade children (9 years, 10 months of age) for information contained in target sentences presented 24 hours earlier was tested by multiple-choice recognition items each consisting of a question about a target sentence followed by three response options. The options consisted of the correct word from the sentence, a new word, and an old, incorrect word that was contained in another sentence on the study trial. The results indicated that the amount of interference produced by old information depended upon the relationship between the sentence in which the old information occurred and the target sentence—being the least when the two were unrelated; the most when the two shared the same subject noun (which also occurred in the stem of the test item for the target sentence); and intermediate when the subjects of the two sentences were synonyms. The interference produced by these manipulations was moderated by instructional strategies and the distance between the target sentence and its variation. The experiment establishes the validity of contextual frequency accrual, a construct logically necessary in extending frequency theory to recognition of information contained in sentences.