In many kinds of scientific experiments, researchers must protect against the experimenter effect. Scientists conducting experiments may give human subjects subtle cues as to their own biases. Body language or tone of voice, for example, could communicate something to the subjects that could affect their performance or responses.
A scientist may, therefore, unwittingly influence the outcome of an experiment, particularly in experiments involving human responses or psychology. This experimenter effect may have an even greater impact on psi experiments.
The term “psi” refers to any psychic phenomenon, such as psychokinesis, telepathy, or clairvoyance. Skeptics, or debunkers, have often dismissed psi based on failed attempts to replicate experiments that give evidence psi exists.
Dr. Garret Moddel at the University of Colorado says, however, that the experimenter effect is part of what could be at play in these failed tests. Furthermore, the subjects’ belief or disbelief in psi may influence their abilities to perform psi tasks.
His student tested 12 subjects, asking them to guess which cards were being held up without being able to see the cards. The subjects were asked beforehand whether they believed in psi. Regardless of their answers, they were randomly given brief literature either in support of psi research or against it, each citing various studies as evidence. Thus the subjects were divided into four groups.
