Written by the Fiveable Content Team • Last updated September 2025
Verified for the 2026 exam
Verified for the 2026 exam•Written by the Fiveable Content Team • Last updated September 2025
Definition
Changes in intensity refer to alterations in the strength or magnitude of a stimulus. When it comes to human perception, changes in intensity must follow a proportional relationship with the original stimulus for them to be noticeable.
The absolute threshold is the lowest level of intensity at which a stimulus can be detected by an individual.
Weber's Law: Weber's law states that there is a constant ratio between the noticeable difference and the original stimulus intensity. In other words, the change needed to be noticed is proportional to the initial intensity.
Also known as the difference threshold, JND refers to the smallest detectable difference between two stimuli. It is related to changes in intensity because it measures how much change is necessary for us to perceive a difference.