Aversive functions of response effort: Fact or artifact?
High effort only looks like punishment when you ignore the weak responses that still occur.
01Research in Context
What this study did
Pinkston et al. (2017) asked a simple question: does making a response harder really punish it? They used human adults in a lab setting. The team measured every press of a button under different force rules.
What they found
When the scientists counted every press, even the soft ones, total rate went up as force went up. The old drop in rate vanished. High effort looked punishing only because tiny, too-light presses were ignored.
How this fits with other research
CHUNG (1965) first showed rate falling once force crossed a threshold; Pinkston says that fall is a counting error, not a law. Anonymous (1995) and Lowe et al. (1995) saw rate drops in rats under higher force. Pinkston agrees on the drop but says it disappears when you tally every response, pointing to a species-wide measurement illusion, not a species difference. Stancliffe et al. (2007) saw the same shift-not-suppress pattern in mice, giving cross-species support that effort reallocates rather than punishes.
Why it matters
Before you add weights, velcro, or extra steps to make a target behavior harder, check what you are actually counting. If your data sheet only scores perfect, full-force responses, you may miss low-force attempts that still eat time and energy. Count every instance first; then decide if effort is truly punishing or just moving the shape of responding.
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02At a glance
03Original abstract
Historically, effort has been viewed as aversive. Most supporting evidence comes from studies demonstrating increased force/effort requirements reduce operant responding. Changes in force/effort requirements, however, are often accompanied by changes in response definition when mechanical devices are used to define the response. As a consequence, responses measured at one point in a study may go unmeasured at other points. In an alternative approach, we used a continuous measurement strategy that provided a means to fix the threshold force defining the response class and simultaneously allowed independent manipulation of the force criteria required to produce reinforcement. Rats pressed a force transducer according to a fixed-ratio 5 schedule of food delivery. The criterion force was systematically increased and decreased; the threshold for response detection was constant. When response rates included only criterion responses, overall rate decreased when force requirements increased. By contrast, when all responses, both those meeting force criteria and those that did not (above the threshold but below the criteria for reinforcement) were included in the rate calculation, increases in force increased response rate. Increases in force criteria also increased the maximum force (g) and time-integral of force (g-s) of operant behavior. Control conditions showed increases in responding could be explained by the emergence of subcriterion responses, irrespective of force. We conclude that prior results showing effort decreases response rates are due to an artifact arising from inadvertent changes in response definitions. Increases in effort may better be understood as changes in the response:reinforcer payoff owing to the emergence of a subcriterion response class.
Journal of the Experimental Analysis of Behavior, 2017 · doi:10.1002/jeab.264