Changes in our surrounding that makes us respond to them are called stimuli.
- The changes in the environmental conditions to which the organisms respond are known as stimuli. Every living organism responds when an external stimulus acts on it.
- The main difference between stimulus and response is that a stimulus is an event or condition which initiates a response, whereas response is the organism’s reaction to a stimulus.
- A stimulus is a change in the external or internal environment which brings about a physiological response, i.e. when applied to any sensory receptor it elicits action or response.
- A stimulus may be internal stimuli (such as changes in blood pressure) or external stimuli (such as touch, sound, smell, taste, vision, etc.)