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A Systematic Evaluation of Variables Underlying Response Effort Manipulations




Polick, Amy

Type of Degree





A number of studies have investigated the effects of manipulating the physical effort required for an individual to emit a response. This research overwhelmingly shows that as force requirements increase, response rates decrease (Friman & Poling, 1995). However, the literature does not clarify the variables underlying the changes in responding after effort is applied. It is not clear whether increasing effort serves as a form of punishment or whether it merely delays access to reinforcement (because increasing effort requires more time to complete the response). This study investigated the relations between physical effort and delay to reinforcement by isolating and manipulating these variables using a concurrent match to sample task. Three participants, aged 4.5, 4.1, 4.2, were presented two behavioral tasks requiring building blocks into a particular shape formation. Each pair of tasks consisted of varying effort (weights added to blocks) and reinforcer delay (time delay added between task completion and access to reinforcement). These variables were systematically manipulated per session. During each choice, one variable was held constant while the other was manipulated. Once presented with the block tasks, the participants were prompted to choose one alternative and match the blocks to a visual stimulus (picture of a shape formation). Each session consisted of two trials in which the student sampled each choice, followed by six consecutive choice trials in which the child was prompted to choose which choice of blocks they wanted to build. The individual’s choice, time to complete the task, accuracy, and verbal responses about preference (they were asked at the end which alternative was their favorite) were recorded over multiple sessions. Results of the study showed that all participants exhibited a strong preference for the low effort task when compared against a high effort one, allocating an average of 96% of choices to the low effort alternative (M=94, 95, and 99% for the three participants). A consistent preference when choosing between low reinforcer delay and high reinforcer delay was evident with one participant (M=93% responses to low delay), and the other two participants showed mixed responding, often switching between low and high delay alternatives during sessions. These results add to the literature existing on response effort and reinforcer delay and suggest that effort and delay affect responding in different ways in a choice context.