In psychology

Psychology

Psychology is the study of the mind and behavior. Its immediate goal is to understand individuals and groups by both establishing general principles and researching specific cases. For many, the ultimate goal of psychology is to benefit society...

, stimuli are energy patterns (e.g. light or sound) which are registered by the senses. In behaviorism

Behaviorism

Behaviorism , also called the learning perspective , is a philosophy of psychology based on the proposition that all things that organisms do—including acting, thinking, and feeling—can and should be regarded as behaviors, and that psychological disorders are best treated by altering behavior...

 and related stimulus–response theories, stimuli constitute the basis for behavior

Behavior

Behavior or behaviour refers to the actions and mannerisms made by organisms, systems, or artificial entities in conjunction with its environment, which includes the other systems or organisms around as well as the physical environment...

, whereas in perceptual psychology

Perceptual psychology

Perceptual psychology is a subfield of cognitive psychology that is concerned specifically with the pre-conscious innate aspects of the human cognitive system: perception....

 they constitute the basis for perception

Perception

Perception is the process of attaining awareness or understanding of the environment by organizing and interpreting sensory information. All perception involves signals in the nervous system, which in turn result from physical stimulation of the sense organs...

.

In the second half of the 19th century, the conception had been established by psychophysics

Psychophysics

Psychophysics quantitatively investigates the relationship between physical stimuli and the sensations and perceptions they effect. Psychophysics has been described as "the scientific study of the relation between stimulus and sensation" or, more completely, as "the analysis of perceptual...

, the "scientific study of the relation between stimulus and sensation", together with the notion of the reflex arc

Reflex arc

A reflex arc is a neural pathway that controls an action reflex. In higher animals, most sensory neurons do not pass directly into the brain, but synapse in the spinal cord...

 constituting a foundational concept of scientific psychology. While at this time "whatever could be controlled by an experimenter and applied to an observer could be thought of as a stimulus." In the context of perception

Perception

Perception is the process of attaining awareness or understanding of the environment by organizing and interpreting sensory information. All perception involves signals in the nervous system, which in turn result from physical stimulation of the sense organs...

, a distinction is made between the distal stimulus (the external, perceived object) and the proximal stimulus (the stimulation of sensory organs).