Medical Definition of All-or-nothing phenomenon
1.
Refers to the phenomenon where the strength of a nerve impulse is not dependent on the strength of the stimulus. Instead, there is a threshold level of stimulus strength that must be reached before the nerve will fire an impulse (at full capacity). Below the threshold, the nerve will not fire at all.
It also refers to the same phenomenon observed in the heart muscle, which will either contract fully or not at all.
In studies of behaviour, it refers to the same phenomenon where a behavioural stimulus will either produce a complete response or no response at all. Also called all-or-nothing principle, all-or-none law, all-or-none responsiveness, etc.
(15 Nov 1997)
Lexicographical Neighbors of All-or-nothing Phenomenon
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