Related Experiment Video
Updated: Apr 28, 2026

Studying Food Reward and Motivation in Humans
Published on: March 19, 2014
Within-session responding as a function of force required for lever press
C L Melville1, L R Rybiski, B Kamrani
1Department of Psychology, McNeese State University, Lake Charles, LA 70609, USA.
Abstract:
Four male Sprague-Dawley rats pressed a lever for food reinforcers delivered by a multiple variable interval 1-min variable interval 1-min schedule. Components alternated every 5 min. The force required to move the lever was 0.25, 0.15, 1.10, 0.75, and 0.50 N in different conditions. Changes in the force requirement did not alter the within-session pattern of responding. These results are consistent with other experiments suggesting that muscle warm-up and fatigue are not sufficient explanations for the within-session pattern of responding.
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