What Is Weber’s Law?

(Last Updated On: February 2, 2023)

Weber’s law, also sometimes referred to as Web-Fechner law, is a principle that quantifies how people perceive a change in a stimulus. According to Weber’s law, the just noticeable difference is a constant proportion of the original stimulus size. The just noticeable difference, also known as the difference threshold, is the smallest possible difference between two stimuli that can be detected at least half the time.

Weber’s law, named after German physiologist Ernst Weber, is a principle of perception that states that the size of the just noticeable difference varies depending upon its relation to the strength of the original stimulus.

How Weber’s Law Works

Weber’s law suggests that whether or not you can detect a change in a stimulus depends on the strength of the original stimulus. For example, imagine that you are holding a small stone in your hand. If someone was to place another rock in the palm of your hand, you would be able to detect the difference.

However, imagine that you were holding a very large rock in your hand, you would likely not notice any difference in weight if someone added a small pebble. Because the small pebble represents such as small change from the heavier original stimulus, you are less likely to detect the change.

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Why Weber’s Law Is Important

Weber’s law demonstrates an important point. Our physiological experiences of the world are relative. The law can be applied to all senses, including touch, vision, hearing, smell, and taste.

However, it is important to note that Weber’s law is not always true and differs depending on the sense involve. For example:

When it comes to weight perception, Weber found that the just noticeable difference was proportional to the original weight. Weber’s law applied generally when it comes to perceiving sounds of higher intensities, but not for lower ones.