Absolute Threshold
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.
- Definition:
The “Absolute Threshold” is a fundamental concept in psychology and sensory physiology, referring to the lowest intensity of a stimulus that can be detected by a person’s senses with at least 50% accuracy. In other words, it represents the point at which a stimulus becomes perceptible to an individual. - Explanation:
The concept of the absolute threshold is relevant across different sensory modalities, such as vision, hearing, taste, touch, and smell. Psychologists and researchers use various experimental methods to determine these thresholds for different senses. - Related Concepts:
Two related concepts are the “difference threshold” (or “just noticeable difference”) and “sensory adaptation.” The difference threshold is the minimum difference in intensity between two stimuli that can be detected reliably. Sensory adaptation, on the other hand, refers to the process by which our senses become less sensitive to a constant stimulus over time. - Usage and Context:
Understanding the absolute threshold helps researchers and clinicians study human perception and sensitivity to various stimuli. It is particularly relevant in areas like psychophysics, where researchers examine the relationship between physical stimuli and the psychological responses they evoke. - Historical Background:
The concept of the absolute threshold was first systematically studied by the German physicist and philosopher Gustav Fechner in the mid-19th century. Fechner’s pioneering work in psychophysics laid the foundation for quantitatively measuring the relationship between physical stimuli and perceptual experiences. - Significance:
The absolute threshold is essential in understanding how humans perceive the world around them. By establishing these thresholds, researchers gain insights into the limits of human sensory capabilities. Additionally, knowledge of the absolute threshold helps in designing experiments, creating sensory devices, and assessing sensory impairments. - References:
Fechner, G. T. (1860). “Elemente der Psychophysik” (Elements of Psychophysics).
