(redirected from unconditioned stimulus)
Also found in: Dictionary, Thesaurus, Medical, Acronyms, Wikipedia.


1. any drug, agent, electrical impulse, or other factor able to cause a response in an organism
2. an object or event that is apprehended by the senses
3. Med a former name for stimulant
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



something that excites to action and motivates behavior. The concept of stimulus is characteristic primarily of those trends in psychology that base behavior analysis on the stimulus-response correlation (classical psychophysics and especially behaviorism, as well as neobehaviorism). The term “stimulus” is also retained in some psychological concepts that in essence supersede the stimulus-response correlation. Thus, for example, in the Würzburg school, a task or an awareness of a goal is considered to be a stimulus. In this case, the term “stimulus” is almost metaphorical. Even further from the term’s original meaning is the treatment it receives in the cultural and historical conceptions of L. S. Vygotskii, who established a functional difference between stimulus objects, at which action is directed, and stimulus means, by which action is accomplished. According to Vygotskii, signs serve as stimulus means.

In sociopsychological studies a distinction is sometimes made between motives as internal excitations and stimuli as external excitations to action (see Chelovek i ego rabota [collection], 1967, pp. 38–39).


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


(control systems)
A signal that affects the controlled variable in a control system.
An agent that produces a temporary change in physiological activity in an organism or in any of its parts.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Pairing a conditioned stimulus with an unconditioned stimulus is referred to as first-order respondent conditioning.
In humans, practically any unconditioned stimulus can be associated with any conditioned stimulus, and the intensity of the conditioned response usually increases with repeated reinforcement.
The effect of two ways of devaluing the unconditioned stimulus after first--and second-order appetitive conditioning.
As is typical of classical conditioning, where the form of the conditioned response tends to replicate that of the unconditioned response to the unconditioned stimulus, the expected increase of ZM activity in the presence of S1 friendly faces and of CS activity in the presence of S1 hostile faces only appeared in those participants who showed the typical pattern of facial responses in the presence of the corresponding expressive faces.
Blocking of inhibitory conditioning within a serial conditioned stimulus-conditioned inhibitor compound: Maintenance of acquired behavior without an unconditioned stimulus. Learning and Motivation, 14, 1-29.
On 75% of the CS+ trials, the screen cleared for 2s before the onset of the unconditioned stimulus, which was a loud burst of white noise (80db) of 5s duration delivered to the subject via the headphones.
In the terminology of classical conditioning, the food is called an unconditioned stimulus that reflexively elicits an unconditioned response (i.e., salivation) (see figure).
Acquisition of instrumental conditioned reinforcement is resistant to the devaluation of the unconditioned stimulus. The Quarterly Journal of Experimental Psychology Section B: Comparative and Physiological Psychology, 58, 19-30.
In a standard selective conditioning procedure, the unconditioned stimulus (US) is not preceded by just one, but by multiple conditioned stimuli (CSs).
Taste aversion conditioning with heat as unconditioned stimulus: The role of taste intensity and preexposure in rats.
One procedure used to generate new affective meaning has been differential Pavlovian conditioning, with an aversive electrocutaneous stimulus as the unconditioned stimulus (US) and pictures of human faces as CSs.
Training consists of exposing the animals to a bright white light (650-700 lux) for 6 s (the conditioned stimulus, CS), paired, after a 2-s delay, with a 4-s vigorous orbital shaking of the tray containing the animals (the unconditioned stimulus, US).