Assessing preferences of individuals with acquired brain injury using alternative stimulus modalities.

PRIMARY OBJECTIVE: To extend previous research on alternative stimulus preference assessment (SPA) modalities to individuals with severe ABI by evaluating the effects of pictorial, verbal and tangible item presentation. RESEARCH DESIGN: Paired-stimulus procedure used for SPA sessions with the order of modalities counterbalanced across participants. Reinforcer assessments (RAs) were experimentally evaluated using an alternating treatments design. A progressive-ratio procedure was used for reinforcer assessment (RA) sessions. METHODS AND PROCEDURES: Six adults with severe ABI. The Assessment of Basic Learning Abilities was conducted to assess discrimination skills; the Reinforcer Assessment for Individuals with Severe Disabilities structured interview was administered to identify items for subsequent evaluations. Three SPA sessions-one of each stimulus modality-were conducted with each participant. Subsequent RAs were conducted using the stimuli ranked as the most highly preferred for each participant. MAIN OUTCOMES AND RESULTS: Each modality identified a different food item with the highest selection percentage for three participants, while three participants had highly consistent SPA results. Subsequent RAs demonstrated that all modalities made valid predictions of foods that would function as reinforcers for programming. CONCLUSIONS: Use of the different direct-observation methods to identify reinforcers for reductive and skill acquisition programming would likely be a useful addition to rehabilitation settings.

Topographical aspects of brief-stimulus presentations: A re-examination of the problem of conditioned reinforcement.

Three pigeons were exposed to second-order schedules in which responding under a fixed-interval (FI) component schedule was reinforced according to a variable-interval (VI) schedule of food reinforcement. Completion of each component resulted in either (1) brief presentation of a stimulus present during reinforcement (paired brief stimulus), (2) brief presentation of a stimulus not present during reinforcement (nonpaired brief stimulus), or (3) no stimulus presentation (tandem schedule). Under the two nonpaired brief stimulus conditions, either a change in keylight color or onset of houselight illumination was used as the brief stimulus. Similar patterns of keypecking occurred under tandem and nonpaired keylight brief-stimulus presentations, whereas nonpaired houselight brief-stimulus presentations generated positively accelerated within-component keypeck patterning for two pigeons. When the same keylight brief stimulus was paired with food, positively accelerated patterns of keypecking were obtained for all pigeons. Differences in the effects of nonpaired brief-stimulus presentations on second-order schedule performance suggest that component schedule patterning under nonpaired brief-stimulus procedures is a function of the particular type of stimulus used (i.e., houselight versus keylight). These results suggest that (1) brief houselight illumination may function as a sensory reinforcer, and (2) a briefly presented food-paired stimulus can function as an effective conditioned reinforcer.

The reinforcing effects of houselight illumination during chained schedules of food presentation.

Pigeons' keypecking was maintained under two- and three-component chained schedules of food presentation. The component schedules were all fixed-interval schedules of either 1- or 2-min duration. Across conditions the presence of houselight illumination within each component schedule was manipulated. For each pigeon, first-component response rates increased significantly when the houselight was extinguished in the first component and illuminated in the second. The results suggest that the increase was not the result of disinhibition or modification of stimulus control by component stimuli, but appears to result from the reinforcement of responding by the onset of illumination in the second component. Additionally, the apparent reinforcing properties of houselight illumination resulted neither from association of the houselight with the terminal component of the chained schedule nor through generalization of the hopper illumination present during food presentation. The results of the present series of experiments are related to previous demonstrations of illumination-reinforced responding and to the interpretation of data from experiments employing houselight illumination as stimuli associated with timeout or brief stimuli in second-order schedules.

Philosophy of mind: coming to terms with traumatic brain injury.

INTRODUCTION: Patients and their families struggle with accepting changes in personality after traumatic brain injury (TBI). A neuroanatomic understanding may assist with this process. OBJECTIVES: We briefly review the history of the Western conceptualization of the Self, and discuss how neuroscience and changes in personality wrought by brain injuries modify and enrich our understanding of our selves and our patients. CONCLUSION: The sense of self, while conflated with the concept of a "soul" in Western thinking, is more rationally considered a construct derived from neurophysiologic structures. The self or personality therefore often changes when the brain changes. A neuroanatomic perspective can help patients, families, and clinicians accept and cope with the sequellae of TBI.