John Henry effect
Encyclopedia
The John Henry effect is an experimental bias introduced into social experiments by reactive
behavior by the control group. It is essentially the opposite of the Hawthorne Effect
.
In a controlled social experiment if a control is aware of their status as members of the control group and is able to compare their performance with that of the treatment group, members of the control group may actively work harder to overcome the "disadvantage" of being in the control group.
For example, if in an educational trial where the school classes who are in the treatment receive an extra support teacher, students who are in the control group may be induced to work harder to overcome that disadvantage.
The term was first used by Gary Saretsky (1972) to describe the behavior of a legendary American steel driver
in the 1870s who, when he heard his output was being compared with that of a steam drill, worked so hard to outperform the machine he died in the process.
Reactivity (psychology)
Reactivity is a phenomenon that occurs when individuals alter their performance or behavior due to the awareness that they are being observed. The change may be positive or negative, and depends on the situation. It is a significant threat to a research study's internal validity and is typically...
behavior by the control group. It is essentially the opposite of the Hawthorne Effect
Hawthorne effect
The Hawthorne effect is a form of reactivity whereby subjects improve or modify an aspect of their behavior being experimentally measured simply in response to the fact that they know they are being studied, not in response to any particular experimental manipulation.The term was coined in 1950 by...
.
In a controlled social experiment if a control is aware of their status as members of the control group and is able to compare their performance with that of the treatment group, members of the control group may actively work harder to overcome the "disadvantage" of being in the control group.
For example, if in an educational trial where the school classes who are in the treatment receive an extra support teacher, students who are in the control group may be induced to work harder to overcome that disadvantage.
The term was first used by Gary Saretsky (1972) to describe the behavior of a legendary American steel driver
John Henry (folklore)
John Henry is an American folk hero and tall tale. Henry worked as a "steel-driver"—a man tasked with hammering and chiseling rock in the construction of tunnels for railroad tracks. In the legend, John Henry's prowess as a steel-driver was measured in a race against a steam powered hammer,...
in the 1870s who, when he heard his output was being compared with that of a steam drill, worked so hard to outperform the machine he died in the process.