This article reviews the practical value of conceptual attempts to specify the circumstances of reinforcement ahead of time. Improvements are traced from the transituational-reinforcer approach of Meehl (1950), through the probability-differential model of Premack (1959, 1965), to the response deprivation and disequilibrium approach (Timberlake, 1980, 1984; Timberlake & Allison, 1974). The application value of each approach is evaluated on the grounds of simplicity, accuracy, and adaptability. The article shows that the disequilibrium approach accounts for and extends current empirically driven techniques of reinforcement control and examines some of its limitations. The disequilibrium approach clarifies how current knowledge can be used to predict more accurately the circumstances of reinforcement and invites the collaboration of applied and basic research in its further development.

No abstract

No abstract

Performing any behavior requires perceiving affordances-whether and how that behavior can be performed. Perception of affordances exhibits action scalingchoices about when to transition between two different modes of behavior reflect the fit between action capabilities and environmental properties. The boundary between distances that are perceived to be reachable with an arm-only reach and those that are perceived to be reachable with an arm-plustorso reach occurs at farther distances for long-armed than for short-armed people, but at the same ratio of objectdistance-to-arm length for both groups. To the extent that perception of affordances is supported by detection of invariant stimulation patterns, perception of a given affordance ought to exhibit action scaling regardless of species. We investigated the heights at which dogs chose to transition from reaching with the head only to rearing (i.e., reaching with the head plus torso). This transition occurred at a taller height for tall than for short dogs, but at the same ratio of shoulder-height-totreat-height for both groups. The results demonstrate a similarity in perception of affordances across species and suggest that perception of affordances is supported by detection of lawfully structured stimulation patterns that may be invariant across species.

A peer‐delivered incidental‐teaching procedure was used to instruct appropriate requesting in adults with moderate to severe mental retardation or autism. Three pairs of group‐home residents participated in an incidental‐teaching procedure to increase appropriate requesting, prompting, and responding of residents during lunch‐preparation sessions. An increase in the number of incidental‐teaching episodes during dinner was obtained, and remained high when lunch‐making training sessions were withdrawn. In addition, during the incidental‐teaching phase, an increase in appropriate requests and overall verbalizations occurred for the peer learners. Changes in appropriate requesting and overall verbalizations also remained higher than baseline when training was withdrawn.