Determinants of contrast in the signal-key procedure: Evidence against additivity theory.

Two experiments are reported that challenge the interpretation of previous results with the signal-key procedure, in which the discriminative stimuli are located on a response key different from the key associated with the operant response requirement. Experiment 1 replicated the procedure of Keller (1974), and found that contrast effects on the operant key occurred reliably for only one of four subjects. High rates to the signal key initially occurred for only one subject, but modifications of the procedure produced substantial rates to the signal key for all subjects. In all cases, however, signal-key behavior was greatly reduced by the addition of a changeover delay which prevented reinforcement within 2 seconds of the last peck to the signal key, suggesting that signal-key pecking was maintained primarily by adventitious reinforcement. Experiment 2 modified the signal-key procedure by using three response keys, so that the discriminative stimuli on the signal key controlled different responses during all phases of training. With this modification, reliable contrast effects on the operant key occurred for all subjects, suggesting that the failure to find contrast in previous studies has been due to the confounding of changes in the discrimination requirements with changes in relative rate of reinforcement. The results challenge the additivity theory of contrast, and suggest that "elicited" behavior plays a minor role, if any, in the determination of contrast effects in multiple schedules.

Preanesthetic preparation of pediatric outpatients: the role of a videotape for parents.

Expanded outpatient surgery for pediatric patients makes it difficult to provide an unhurried and thorough preoperative visit. A useful component could be a videotape to be seen by parents at the time of their initial hospital visit. For this study, a videotape was made that included an actual induction of anesthesia procedure, information about pediatric anesthesia, and a discussion of the risks of injury or death during anesthesia. To decrease anxiety from discussion of risk, monitoring equipment was shown and explained. This survey investigated whether, after seeing the tape, the parents of children scheduled for outpatient surgery thought they were better informed and less anxious about the child's anesthetic. During a preoperative clinic visit, an interviewer introduced the tape and its purpose to 31 parents of 25 children, then asked a series of standard questions. When asked directly, most parents (74%) said the film did not change their concerns about the anesthetic, although 42% of the parents of the children with no surgical history reported decreased concern. In contrast, 84% to 97% of the parents considered seven specific aspects of the film to be helpful in reducing concern. Half were reminded of issues to be discussed with the child's anesthesiologist. Most parents (65%) appeared to accept discussion of the risk of perioperative death, although some had strongly negative reactions. The results suggest that a supportive preoperative tape can acquaint parents with the basis for anesthesiologists' concerns and facilitate the preoperative visit. Seeing an actual anesthetic may help to reassure parents about the anesthetic care their children will receive.(ABSTRACT TRUNCATED AT 250 WORDS)

The role of imagery in hypnosis: an information processing approach.

Imagery is widely agreed to be an important component of hypnosis. The theoretical framework from which to conceptualize the role of imagery in hypnosis, however, has remained controversial. A model is presented which attempts to reconceptualize hypnotic imaginal processing in terms of current theory and research in cognitive psychology and psychophysiology. This model draws from a propositional approach to imagery (e.g., Pylyshyn, 1973), particularly as adapted by Lang's (1979) bioinformational theory. It is argued that the hypnotic image is fundamentally more complex than simple iconic mental representation, containing instead both stimulus and response components. It is proposed that the critical properties of the hypnotic image are not the stimulus components or propositions which give rise to the experience of the image but instead are response propositions which are associated with overt behavior. Processing of these response propositions is conceptualized as a negative feedback system between the brain and effector site. Some preliminary sources of support as well as implications and research suggested by this model are discussed.