When1: 1850
When2: 1867
Who: Hermann Ludwig Ferdinand von Helmholtz [Helmholtz, Hermann Ludwig Ferdinand von]
What: physiologist/physicist/inventor
Where: Germany
works\ Treatise on Physiological Optics [1856 to 1867]; On the Sensations of Tone [1863]; ophthalmoscope [1851]; ophthalmometer
Detail: He lived 1821 to 1894 and founded perceptual physiology {ophthalmoscope, Helmholtz}. He developed Young-Helmholtz trichromatic color-vision theory and studied lens accommodation. He first timed nerve-signal conduction rate and muscle-action times [1850]. Speed at which electrical impulses travel along nerve fibers limits human reaction time. Pitch discrimination depends on resonance {fixed pitch theory}.
Epistemology
People cannot know external physical events and only have neural signals. Neural signals from senses gain meaning from learned associations, which depend on assumptions that can be incorrect. Perceptions are unconscious inferences. People cannot experience or introspect how they perceive or think. People cannot know data on which brain bases perceptions and beliefs. During perceptions and decisions to perform muscle movements, nerve signals switch. Body sense receptors receive and analyze physical energies from outside world to make independent, simple, and unnoticeable sensations, and brains learn to perceive objects and events that probably produced sensations {classical theory of psychology}.
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Date Modified: 2022.0224