In scientific research and
psychotherapy
Psychotherapy (also psychological therapy, talk therapy, or talking therapy) is the use of Psychology, psychological methods, particularly when based on regular Conversation, personal interaction, to help a person change behavior, increase hap ...
, the subject-expectancy effect, is a form of
reactivity that occurs when a
research subject expects a given result and therefore unconsciously affects the outcome, or reports the expected result. Because this effect can significantly
bias
Bias is a disproportionate weight ''in favor of'' or ''against'' an idea or thing, usually in a way that is inaccurate, closed-minded, prejudicial, or unfair. Biases can be innate or learned. People may develop biases for or against an individ ...
the results of experiments (especially on
human subjects),
double-blind
In a blind or blinded experiment, information which may influence the participants of the experiment is withheld until after the experiment is complete. Good blinding can reduce or eliminate experimental biases that arise from a participants' expec ...
methodology is used to eliminate the effect.
Like the
observer-expectancy effect, it is often a cause of "odd" results in many experiments. The subject-expectancy effect is most commonly found in
medicine
Medicine is the science and Praxis (process), practice of caring for patients, managing the Medical diagnosis, diagnosis, prognosis, Preventive medicine, prevention, therapy, treatment, Palliative care, palliation of their injury or disease, ...
, where it can result in the subject experiencing the
placebo effect
A placebo ( ) can be roughly defined as a sham medical treatment. Common placebos include inert tablets (like sugar pills), inert injections (like saline), sham surgery, and other procedures.
Placebos are used in randomized clinical trials ...
or
nocebo effect, depending on how the influence pans out.
Example
An example of a scenario involving these various effects is as follows: A woman goes to her doctor with a problem. The doctor diagnoses with certainty, and then clearly explains the diagnosis and the expected route towards recovery. If he does this convincingly, calming her, removing fear and instilling hope, she will likely, through the positive expectancy, experience the placebo effect, aiding in her recovery.
On the other hand, if her doctor had had little time for her, was uncertain about the diagnosis, and had given her a
prescription, combined with a message along the lines of, "this may help sometimes", and added a message about possible horrible
side effects
In medicine, a side effect is an effect of the use of a medicinal drug or other treatment, usually adverse but sometimes beneficial, that is unintended. Herbal and traditional medicines also have side effects.
A drug or procedure usually used ...
(combined, say, with the patient having talked to a neighbor who also speaks along the same lines about the horrible side effects), then the chance of negative subject-expectancy, or
nocebo, becomes quite large.
See also
*
Hawthorne effect
*
Pygmalion effect
Bibliography
*
{{DEFAULTSORT:Subject-Expectancy Effect
Cognitive biases