unconditioned stimulus


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unconditioned stimulus

n. Psychology
A stimulus that evokes an unconditioned response.

unconditioned stimulus

n
(Psychology) psychol any stimulus evoking an unlearnt response, esp in the context of classical conditioning, in which the conditioned stimulus is followed by the unconditioned one
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In this study, macaques were trained in a feature-negative discrimination (A+/AX-) paradigm with an appetitive unconditioned stimulus. Activations above baseline responding of single dopamine neurons in the midbrain were recorded with intracranial electrodes as the conditioned response.
Priming-produced facilitation or diminution of responding to a Pavlovian unconditioned stimulus. Journal of Experimental Psychology: Animal Behavior Processes, 7, 295-312.
Concentrated lemon juice was used as unconditioned stimulus (US), which has been used in previous studies to produce a salivary response (see Pangborn, 1968).
A 60 W light was switched on for 5 s alternately in the two compartments and used as a conditioned stimulus (CS), which preceded an electric shock (1 mA for 5 s) by 5 s (the unconditioned stimulus).
Typically, an unconditioned response or reflex that is elicited by an unconditioned stimulus will show habituation if the stimulus is repeated (Gluck et al., 2008).
In an extinction procedure conditioned responding (CR) diminishes when a conditioned stimulus (CS) is presented in absence of the unconditioned stimulus (US); however, if the CS is presented in a different array of contextual cues, such as a different chamber, the CR reappears, this effect is known as context renewal.
The association between an odor, as a conditioned stimulus (CS), and electrical footshock, as an unconditioned stimulus (US), is an effective model to study fear-induced behavior.
The basic theory is that when an initial neutral and non-anxiety provoking event (unconditioned stimulus) is paired with an aversive experience, then an anxiety response ensues (unconditioned response).
(19) Unconditioned stimulus response (UCR) decreases when the stimulus may be predicted, a phenomenon called UCR diminution.
Previous studies have implicated a brain structure called the amygdala in the acquisition and expression of conditioned fear, this occurring when a stimulus (the conditioned stimulus, CS) becomes associated with an aversive object or event (the unconditioned stimulus, UCS).
One of the sounds (CS+, conditioned stimulus) was followed 15 times by a noxious stimulus (UCS, unconditioned stimulus; electrical stimulation of the left index finger whose intensity twice exceeded the average pain threshold in a comparable control group).