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.

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.

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.

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.