Cognitive Scaffold

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MENTAL MODEL · M3298

John Henry Effect

John Henry Effect
BehaviorHigh supportPsychology
Included
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Version 1.0.0 · Updated 2026-07-31

CORE DEFINITION

In a controlled experiment, the control group (those not receiving the new intervention) knows they are competing with the experimental group (those receiving the new intervention) and, in order to prove they are not inferior, performs exceptionally well, leading to biased experimental results. It originates from the legend of John Henry, a worker who died from overwork while trying to outperform a steam drill.

SCAFFOLDING EFFECT

psychology

Reduce cognitive load

Eliminating competitive interference. When piloting new tools in an enterprise, be wary that teams not using the new tool may work overtime out of 'defiance', thereby masking the true effectiveness of the new tool.

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In a controlled experiment, the control group, aware of competing with the experimental group, performs exceptionally well, distorting the estimate of the intervention's effect. This is a 'Hawthorne-like' competitive interference that makes the new intervention appear ineffective or weak, stemming from compensatory effort.

MINIMUM ACTION

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Source support: Explicit

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    zh.wikipedia.orghttps://zh.wikipedia.org/wiki/%E7%B4%84%E7%BF%B0ZH · Explicit
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