The minimum amount of stimulation required to trigger a reaction or produce a sensation. The absolute threshold is measured across several trials. It is the lowest or weakest level of stimulation (e.g., the slightest, most indistinct sound) that can be detected on 50% of trials. Although the name suggests a fixed level at which stimuli effectively elicit sensations, the absolute threshold fluctuates according to alterations in receptors and environmental conditions. Also called absolute limen (AL); detection threshold; sensation threshold.
This is a term that many students have a difficult time understanding, but it’s not as complex as it might seem. One formal definition is that the absolute threshold is the smallest intensity of a stimulus that has to be present for the stimulus to be detected. Let’s use an example to clear this up. Think of an electric burner on a stove. Imagine turning that burner on and then placing your hand directly on it. At first, you won’t feel much heat because it takes time for the burner to heat up. But at some point it will get hot enough for you to detect…meaning, there is some temperature that is just hot enough for you to notice it. This isn’t the point at which you get burned, but the point at which it is just hot enough for you to detect the presence of the heat.