Behavioral contrast and type of reward: Role of elicited response topography

Abstract

Groups of pigeons were exposed to multiple variable-interval variable-interval and multiple variable-interval extinction schedules of either food or water reinforcement for keypecking. Discriminative stimuli associated with component schedules were located either on the operant key or on a second "signal" key. When the stimuli were projected on the operant key, positive contrast appeared during discrimination conditions with either food or water as the reinforcer. When the stimuli were projected on the signal key, overall responding to the operant and signal keys showed contrast with food, but negative induction with water as the reinforcer. In the latter condition, the signal for the variable-interval shcedule of water reinforcement elicited a variety of water-related behavior, only some of which was directed at the signal. Thus, the type of reward and location of discriminative stimuli interacted to determine the presence or absence of behavioral contrast effects. In large part, these results support and extend the autoshaping view of contrast.A good deal of research suggests that the phenomenon of positive behavioral contrast (Reynolds, 1961) may result from a combination of operant and respondent (or autoshaping, Brown & Jenkins, 1968) factors. Positive contrast appears during multipleschedule procedures when, for example, a multiple variable-interval variable-interval (mult VI VI) schedule is changed to multiple variable-interval extinction (mult VI EXT). As response rate declines in the EXT component, response rate often increases in the unchanged VI component, and this divergence of response rates is labeled positive contrast. According to the autoshaping view of contrast, a change from mult VI VI to mult VI EXT introduces a stimulusreinforcer contingency into the discrimination situation. The stimulus correlated with VI may engender elicited, or autoshaped responses, which sum with ongoing operant responses to increase response rate

Differences between rates of responding emitted during simple and multiple schedules

“…Several studies have supported this prediction by showing that contrast does not occur when diffuse stimuli signal the components (Bottjer, Scobie, & Wallace, 1977;Redford & Perkins, 1974;Schwartz, 1974Schwartz, , 1975 or when the discriminative stimuli are moved to another key (Keller, 1974;Schwartz, 1975;Schwartz, Hamilton, & Silberberg, 1975;White & Braunstein, 1979). But a growing number of studies have contradicted the additive theories by reporting contrast when the stimuli are diffuse (Hearst & Gormley, 1976;Westbrook, 1973) or when the stimuli appear on a second key (Schwartz, 1978;Woodruff, 1979).…”

Behavioral contrast and responding during multiple food-food, food-water, and water-water schedules

“…But, few studies have asked whether contrast occurs when the quality or type of reinforcer obtained from the variable component changes. Some studies have reported contrast with an instrumental response when both the rate and type of reinforcer presented during the other component varied (Beninger, 1972;Beninger & Kendall, 1975;Premack, 1969;Woodruff, 1979). But, only one experiment reported contrast that could be clearly attributed to changes in the quality of the reinforcer alone (Ettinger, McSweeney, & Norman, 1981).…”

A method for automatically recording topographical differences in pigeons’ keypecking for food and water reinforcers

“…Because of the cumbersome nature of such analog recordings, no quantitative analyses of these data were conducted and only sample records were presented. A similar procedure was used by Woodruff (1979) and Woodruff and Williams (1976).…”