What do you call the the weakest amount of a stimulus required to produce a sensation?
Receptors for each sensory system are limited by the amount of stimulation necessary to elicit a sensation and by the amount of stimulus change that can be detected. In the field of psychology called psychophysics, relationships between physical stimuli and psychological experience are studied. One technique to study such relationships is called the method of constant stimuli, in which stimuli of varying intensities are presented in random order to a subject. The results are used to determine the absolute threshold—the minimum intensity detected by a subject 50% of the time. (Your dog, for instance, has a much lower absolute threshold for sound than you do and hears a car in the driveway before you hear the knock on the door.) Show
The difference threshold—the minimum (physical) distinction between stimulus attributes that can be detected 50% of the time—is also of concern. The difference threshold is also called a just noticeable difference (JND). Ernst Weber, a well‐known early investigator, observed that regardless of their magnitude, two stimuli must differ by a constant proportion for their difference to be detectable. His observations are formulated as Weber's law, which states that the “just noticeable difference” is a constant fraction of the stimulus intensity already present. (If a room is quiet, you can hear a faint knock at the door. But if your CD player is blaring, it takes a loud bang on the door for you to hear it.) If you are exposed to a stimulus that doesn't change over a period of time, sensory adaptation occurs, and you become less sensitive to the stimulus. If you have to study in a room with a constant noise outside, for example, you will usually eventually adapt to the noise, and it will become less offensive. Signal detection. Factors other than the magnitude of the stimulus also affect sensory discriminations. When a discrimination—that is, the detection of a stimulus (a signal)—must be made against a background of noise, the procedure is called signal detection. Signal detection theory takes into account the fact that people are making decisions as they make sensory discriminations. When they attempt to separate a signal change from its background, they may guess, have biases in their judgments, or become less vigilant during the judging process. Knowledge of signal detection theory is useful in many situations—for instance, if one were teaching people to detect accurately small blips on radar screens in an air control tower. Another aspect of sensory perception, subliminal perception (perception without awareness), has been of interest in recent years. However, the data concerning the existence of the phenomenon are still controversial. October 22, 1850 Gustav Fechner's Law "S = k Log R"
But first we need some basic concepts. Psychophysical Problems Introduced
Fechner's idea was to markoff equally different sensations in terms of the stimuli that produce them. In the picture below:The World of Stimulation--the Physical World
Fechner's Law Redux
©2002 by Burrton Woodruff. All rights reserved. Modified Friday, June 7, 2002 What is the lowest level of stimulus?An absolute threshold is the smallest level of stimulus that can be detected, usually defined as at least half the time. The term is often used in neuroscience and experimental research and can be applied to any stimulus that can be detected by the human senses including sound, touch, taste, sight, and smell.
What is the smallest amount of a stimulus required for detection called?An absolute threshold is the smallest amount of stimulation needed for a person to detect that stimulus 50% of the time. This can be applied to all our senses: The minimum intensity of light we can see.
Is called the lowest level at which an individual can experience a sensation?The lowest level at which an individual can experience a sensation is called the absolute threshold. The point at which a person can detect a difference between “something” and “nothing” is that person's absolute threshold for that stimulus.
What is the name for the least amount of energy required for a sensation to take place?Explanation: The minimum amount of energy for a stimulus to be registered as a sensation is known as the absolute threshold. Any stimulus that occurs too weakly to surpass this threshold will not result in a sensation, and will thus be undetected.
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