Experimenter expectancy in resistance to respiratory air flow.

OBJECTIVE

The effect of experimenter expectancy was investigated on the resistance to respiratory air flow, measured as total respiratory resistance (Rt) in healthy individuals.

METHOD

Each of three naive experimental assistants collected air flow resistance responses from 30 subjects who they had been told were either likely or unlikely to respond to the suggestion of breathing difficulty.

RESULTS

The subjects were assigned to the two conditions at random. The subjects who were described to the experimenters as being likely to respond exhibited greater Rt increases to bronchoconstriction suggestion than did the subjects who were described as unlikely to respond.

CONCLUSIONS

These findings confirmed the presence of a source of variance that has not been considered previously in suggestion studies.