Stimulus (psychology)

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In psychology, a stimulus is an energy change (such as light or sound) which is registered by the senses. In behaviorism and related stimulus–response theories, a stimulus constitutes the basis for behavior, whereas it constitutes the basis for perception in perceptual psychology.[1] In this context, a distinction is made between the distal stimulus (the external, perceived object) and the proximal stimulus (the stimulation of sensory organs).[2]

In contemporary experimental psychology the term stimulus is usually used to describe the event or object to which a response is measured. Thus, not everything that is presented to participants qualifies as stimulus: For example, a fixation cross is not said to be a stimulus, because it merely serves to center participants' gaze at the center of the screen. Also, it is uncommon to refer to longer events (e.g. the Trier Social Stress Test) as a stimulus, even if a response to such an event is measured.

History[edit]

In the second half of the 19th century, the term stimulus was coined in psychophysics by defining the field as the "scientific study of the relation between stimulus and sensation".[3] This may have led James J. Gibson to conclude that "whatever could be controlled by an experimenter and applied to an observer could be thought of as a stimulus" in early psychological studies with humans, while around the same time, the term stimulus described anything eliciting a reflex in animal research.[4]

The stimulus concept in Behaviorism[edit]

The concept stimulus was essential to Behaviorism and the behavioral theory of B. F. Skinner in particular. Within such a framework several kinds of stimuli have been distinguished (see also Classical Conditioning):

An eliciting stimulus was defined as a stimulus that precedes a certain behavior and thus causes a response. A discriminative stimulus in contrast increases the probability of a response to occur, but does not necessarily elicit the response. A reinforcing stimulus usually denoted a stimulus delivered after the response has already occurred; in psychological experiments it was often delivered on purpose to reinforce the behavior. Emotional stimuli were regarded as not eliciting a response. Instead, they were thought to modify the strength or vigor with which a behavior i carried out.[5]

See also[edit]

References[edit]

  1. ^ "Stimulus". In: Richard L. Gregory (Ed.), The Oxford Companion to the Mind, Oxford, N.Y.: Oxford University Press.
  2. ^ http://www.learner.org/discoveringpsychology/07/e07glossary.html
  3. ^ Gescheider, G. (1997). Psychophysics: the fundamentals (3rd ed.). Lawrence Erlbaum Associates. p. ix. ISBN 0-8058-2281-X. 
  4. ^ Gibson, James J. (1960): "The Concept of the Stimulus in Psychology". American Psychologist, 15, pp. 694–703, here p.694.
  5. ^ Skinner, B. F. (1938). The Behavior of Organisms: An Experimental Analysis. New York.