Stimulus vs Response
Environment is an ever-changing place that always demands the organisms to adapt accordingly. Even the slightest of the changes in the environment could be very important for an organism, given there are microorganisms everywhere. All these could be described using stimulus and response. When there is a change in the environment, an organism would take it as a stimulus and responds accordingly. That respond could be a stimulus for another organism sometimes; it could be the stimulus in the second organism, and can cause to respond.
Stimulus
Changes in the environment lead to the organisms as stimuli (plural of stimulus). Therefore, it could be envisaged that any change in the environment would be a stimulus if that could create a nervous impulse in an animal. However, there are no nerves in trees to make nervous impulses, yet stimuli are generated inside plants due to environmental changes. The created stimuli inside organisms do not necessarily have to be nervous impulses, but physiological changes are quite enough. Therefore, any environmental change that can cause a physiological alteration in an organism is a stimulus.
A stimulus leads to another process in an organism, which could be another stimulus for another process. When the intensity of sunlight goes high, the aperture of the eye becomes small. The increase of sunlight intensity was the stimulus; a nervous impulse with information about the high amount of sunlight is taken to the brain, and that nervous impulse becomes the stimulus for the brain to trigger necessary actions to control the over exposure. A plant at a shade shows phototropic movements when there is a change of sunlight intensity from one side to the other. Increase in sunlight at one side causes the hormones to move to the other side of the plant stem, then the side at shade grows fast with more cells than the first side, and the stem grows towards the sunlight. There are infinite amounts of changes that can cause stimuli in organisms. A stimulus could be either external or internal, and those could be of any magnitude.
Response
Response is the output or the result of a stimulus. When a stimulus is generated, the biological organisms are adapted to react to undo the effect of the change that caused the stimulus. When someone’s armpits are tickled, the hands automatically come down to close the armpit. Tickling was the stimulus and hands responded by closing the armpits. When a car driver sees a barrier, the vehicle is moved away from it.
Responses are mainly of two types known as Learned Behaviours and Instinct Responses. The above stated tickling example describes the instinct response. In other words, the instinct response is the natural reaction of an organism to a certain stimulus. The learned behaviour should be taught by someone else or self-taught. When the consequences have been studied or experienced in a previous occasion for a particular stimulus, the response action would be under way. The car driver has learned the consequences of a car crash and the car is driven away from the barrier to evade the danger through learned behaviour.
What is the difference between Stimulus and Response?
• Stimulus is the first event that takes place, and the response is the result.
• A stimulus could be of any magnitude, but the response could never go beyond the highest capability of an organism.
• Stimulus cannot be always controlled, especially the external stimuli, whereas response could be controlled.
• Stimulus determines the response, but it never happens the other way around.