The elderly and high technology medicine: A case for individualized,autonomous allocation

The issues involved in decision making about the aggressiveness of future medical care for older persons are explored. They are related to population trends, the heterogeneity of older persons and a variety of factors involved in individual preferences. Case studies are presented to illustrate these points, as well as a review of pertinent literature. The argument is offered that, considering these many factors, a system of flexible, individualized care by informed patient preference, is more rational than the rationing of technological services by age.     

STIMULUS (INSTRUCTIONAL) FADING DURING EXTINCTION OF SELF-INJURIOUS ESCAPE BEHAVIOR

Three individuals with developmental disabilities were exposed to a series of assessment conditions to identify the source of reinforcement for their self-injurious behavior. In each case, self-injury occurred most often in instructional (demand) situations containing a brief time-out from the task contingent on self-injury, indicating that the behavior was an escape response (i.e., maintained by negative reinforcement). Treatment was implemented in a multiple baseline across subjects design and consisted of extinction (prevention of escape) plus instructional fading (initial elimination of instructions followed by their gradual reintroduction). Results showed that the combined treatment produced immediate and large reductions in self-injury that were maintained as the frequency of instructions was increased across sessions to match the original baseline rate of presentation. Results of a component analysis conducted with 1 subject suggested that stimulus fading accelerated the behavior-reducing effects of extinction.     

Effects of differences between stimuli, responses, and reinforcer rates on conditional discrimination performance

In a discrete-trial conditional discrimination procedure, 4 pigeons obtained food reinforcers by pecking a key with a short latency on trials signaled by one stimulus and by pecking the same key with a long latency on trials signaled by a second stimulus. The physical difference between the two stimuli and the temporal separation between the latency values required for reinforcement were varied factorially over four sets of conditions, and the ratio of reinforcer rates for short and long latencies was varied within each set of conditions. Stimulus discrimination varied directly with both stimulus and response differences and was unaffected by the reinforcer ratio. Sensitivity to reinforcement, estimated by generalized-matching-law fits to the data within each set of conditions, varied directly with the response difference but inversely with the stimulus difference arranged between sets of conditions. Because variations in stimulus differences, response differences, and reinforcer differences did not have equivalent effects, these findings question the functional equivalence of the three terms of the discriminated operant: antecedent stimuli, behavior, and consequences.     

Delayed and current stimulus control in successive discriminations

In a successive discrimination in which successively alternating red and green hues signaled component variable-interval schedules, sensitivity of the ratio of responses in the two components to variation in the component reinforcer ratio decreased systematically during the course of the component. This decrease in stimulus control or discrimination over the course of the component was shown to be the result of delayed control of responding during the component by the stimulus transition between components. When the red–green stimulus transition was altered by interpolating a white stimulus at the end of each 60-s component, discrimination at the beginning of the component (measured by the power-function exponent for sensitivity to reinforcement) was reduced. Conditions with the white stimulus inserted in other quarters of the component indicated that the current discriminative stimulus exerts control over responding throughout the component, whereas during about the first half of the component, response differentials are influenced by the transition between discriminative stimuli.     

The expected likelihood of transitivity of preference

May's model of pairwise preference determination is used to assess the expected likelihood that a subject's pairwise preference comparisons on three alternatives will be transitive. A closed form representation for this expected likelihood is obtained for each situation considered. When the subject is assumed to act precisely according to rankings on attributes with May's model, the computed expected likelihoods the relatively large. When the subject becomes a probabilistic chooser, as defined in a specific manner, expected likelihoods of transitivity decrease significantly from corresponding values with May's model. For a probabilistic Chooser, there is a significant likelihood that the subject might yield transitive pairwise preferences substantially different than the results suggested by May's model.This research was supported by a grant from the General University Research Program and through a fellowship from the Center for Advanced Study, both of the University of Delaware. Very helpful input from John H. Antil, Meryl P. Gardner, and James M. Munch is also acknowledged.     

EMERGENCE OF REINFORCER PREFERENCE AS A FUNCTION OF SCHEDULE REQUIREMENTS AND STIMULUS SIMILARITY

Tustin (1994) recently observed that an individual's preference for one of two concurrently available reinforcers under low schedule requirements (concurrent fixed-ratio [FR] 1) switched to the other reinforcer when the schedule requirements were high (concurrent FR 10). We extended this line of research by examining preference for similar and dissimilar reinforcers (i.e., those affecting the same sensory modality and those affecting different sensory modalities). Two individuals with developmental disabilities were exposed to an arrangement in which pressing two different panels produced two different reinforcers according to progressively increasing, concurrent-ratio schedules. When two dissimilar stimuli were concurrently available (food and a leisure item), no clear preference for one item over the other was observed, regardless of the FR schedules in effect (FR 1, 2, 5, 10, and 20). By contrast, when two similar stimuli were concurrently available (two food items), a clear preference for one item emerged as the schedule requirements were increased from FR 1 to FR 5 or FR 10. These results are discussed in terms of implications for conducting preference assessments and for selecting reinforcers to be used under training conditions in which response requirements are relatively high or effortful.     

DIRECT AND COLLATERAL EFFECTS OF RESTRAINTS AND RESTRAINT FADING

Mechanical restraints are commonly used to reduce the risks associated with severe self-injurious behavior (SIB), but may result in movement restriction and adverse side effects (e.g., bone demineralization). Restraint fading may provide a method for decreasing SIB while increasing movement and reducing these side effects. In the current investigation, rigid arm sleeves and restraint fading (gradually reducing the rigidity of the sleeves) were used with 3 clients who engaged in hand-to-head SIB. Restraints and fading reduced the hand-to-head SIB of all clients. However, for 1 client, the addition of a water mist procedure further reduced SIB to near-zero levels. For a 2nd client, another form of SIB developed that was not prevented by the rigid sleeves. For a 3rd client, a topography of SIB that was not physically prevented by the rigid sleeves was also reduced when restraints and fading were introduced.     

Nodality effects during equivalence class formation: An extension to sight-word reading and concept development

Three students with moderate disabilities were taught to read and match-to-sample sight words comprising stimulus sets based upon the four food groups. We taught students conditional discriminations within four four-member sets using a single-sample/four-comparison procedure. Students were taught A-B, B-C, and C-D conditional discriminations for each of the four potential stimulus classes. Subsequent probes tested for relations based upon symmetry and one-node and two-node transitivity. The performances for all students indicated that symmetric relations emerged before one-node transitive relations, and that one-node transitive relations emerged before two-node transitive relations. These results are consistent with a pattern of responding, referred to as a "nodality effect," in which relations with fewer nodes are demonstrated prior to the demonstration of relations with a greater number of nodes. These results extend this area of research to sight-word reading for students with moderate disabilities.     

Treatment of escape-maintained aberrant behavior with escape extinction and predictable routines

We evaluated the effects of two daily activity schedules on 2 participants' rates of aberrant behavior and their compliance. Functional analysis identified the operant function of the participants' aberrant behaviors to be escape from tasks. Participants were taught to use stimuli contained in daily schedules, and were tested based on a modified stimulus-equivalence model that consisted of flash cards and activity schedules comprised of words or photographs that corresponded to the participants' daily activities. On pretests, the participants demonstrated simple and conditional discriminations with the photographs but not with the printed stimuli. A time-delay procedure was used to teach the participants to name the flash cards. Following training, the printed activity schedules corresponded to lower rates of problem behavior and higher rates of compliance than the photographic activity schedules. Performance on posttests indicated the establishment of functional classes of stimuli involving the flash cards and activity schedules even though this type of correspondence was not directly trained.     

THE EFFECTS OF CHOICE AND TASK PREFERENCE ON THE WORK PERFORMANCE OF ADULTS WITH SEVERE DISABILITIES

We evaluated the effects of choice versus the assignment of tasks of varying preferences on the work engagement of adults with severe disabilities. The combined results of two experiments suggest that the relative preference for a task may be an important variable in the effectiveness of choice for some individuals.