 | This articleneeds additional citations forverification. Please helpimprove this article byadding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "Stimulus" psychology – news ·newspapers ·books ·scholar ·JSTOR(January 2024) (Learn how and when to remove this message) |
Inpsychology, astimulus is any object or event that elicits a sensory or behavioral response in an organism. In this context, a distinction is made between thedistal stimulus (the external, perceived object) and theproximal stimulus (the stimulation of sensory organs).[1]
The study of the stimulus in psychology began with experiments in the 18th century. In the second half of the 19th century, the termstimulus was coined inpsychophysics by defining the field as the "scientific study of the relation between stimulus andsensation". This may have ledJames 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 termstimulus described anything eliciting areflex in animal research.
The stimulus concept was essential tobehaviorism and behavioral theories ofB. F. Skinner andIvan Pavlov in particular. Within such a framework several kinds of stimuli have been distinguished.
In the theory ofclassical conditioning,unconditioned stimulus (US) is a stimulus that unconditionally triggers an unconditioned response (UR), whileconditioned stimulus (CS) is an originally irrelevant stimulus that triggers a conditioned response (CR). Ivan Pavlov's dog experiment is a well-known experiment that illustrates these terms. The unconditioned stimulus is the dog's food that would naturally cause salivation, which is an unconditioned response. Pavlov then trained the dog by ringing the bell every time before food. The conditioned stimulus is the ringing bell after training, which causes salivation as a conditioned response.[3][page needed]
Moreover, aneliciting stimulus was defined as a stimulus that precedes a certain behavior and thus causes a response. Adiscriminative stimulus in contrast increases the probability that a response will occur but does not necessarily elicit the response. Areinforcing 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 is carried out.[4][page needed]
