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The absolute threshold can be compared to the difference threshold, which is the measure of how different two stimuli must be for the subject to notice that they are not the same. [ 2 ] Vision
In measuring sensory threshold, noise must be accounted for. Signal noise is defined as the presence of extra, unwanted energy in the observational system which obscures the information of interest. As the measurements come closer to the absolute threshold, the variability of the noise increases, causing the threshold to be obscured. [5]
A threshold (or limen) is the point of intensity at which the participant can just detect the presence of a stimulus (absolute threshold [15]) or the difference between two stimuli (difference threshold [7]). Stimuli with intensities below this threshold are not detectable and are considered subliminal.
The JND is a statistical, rather than an exact quantity: from trial to trial, the difference that a given person notices will vary somewhat, and it is therefore necessary to conduct many trials in order to determine the threshold. The JND usually reported is the difference that a person notices on 50% of trials.
The absolute threshold of hearing (ATH), also known as the absolute hearing threshold or auditory threshold, is the minimum sound level of a pure tone that an average human ear with normal hearing can hear with no other sound present. The absolute threshold relates to the sound that can just be heard by the organism.
Differential threshold or just noticeable difference (JDS) is the smallest detectable difference between two stimuli, or the smallest difference in stimuli that can be judged to be different from each other. [8] Weber's Law is an empirical law that states that the difference threshold is a constant fraction of the comparison stimulus. [8]
In physiology, psychology, or psychophysics, a limen or a liminal point is a sensory threshold of a physiological or psychological response. Such points delineate boundaries of perception; that is, a limen defines a sensory threshold beyond which a particular stimulus becomes perceivable, and below which it remains unperceivable.
The absolute threshold for vision is the minimum amount of sensation needed to elicit a response from photoreceptors in the eye. This amount of sensation has a definable value and is often considered to be the amount of light present from someone holding up a single candle 30 miles away, if one's eyes were adjusted to the dark. [7]