Contributions of Herman von Helmholtz in experimental psychology, his views and contributions.

1. CONTRIBUTIONS OF HERMAN VON HELMHOLTZ IN EXPRIMENTAL
PSYCHOLOY:
The gap between psychology and physiology was made smaller by
Helmholtz, as he discovered theories concerning neural impulses,
perception and audition. During the nineteenth century psychophysical
measurement of the relation between the physical properties of the
stimulus and the resultant sensation spurred the growth of experimental
psychology. His contributions in experimental psychology are given
below:
1. In early 1850’s he became interested in how we form an image in the brain from sensory
perception in the eye. He was the first one to argue that we have to learn how to see, using
what he termed a process of ‘ Unconscious Interference’ and he understood the importance
of optical illusion in the formation of image in brain. He invented a hand held instrument
‘Ophthalmoscope’ in 1851 that allowed one to look into the eye.
FIG 2 HELMHOLTZ OPHTHALMOSCOPE
It consisted of half silvered mirror that directs external light into patients eye and then
back through instrument into observer’s eye. Helmholtz also designed a device used to
measure the curvature of the eye called an ‘Ophthalmometer’. Using these devices he
advanced the theory of three-color vision (there are three receptors in the retina that are
responsible for the perception of color. One receptor is sensitive to the color green, another
to the color blue and a third to the color red).
2. In 1852, Helmholtz conducted the measurement of the speed of a nerve impulse. It had
been assumed that such a measurement could never be obtained by science, since the speed
was far too great for instruments to catch. Some physicians even used this as proof that
FIG 1 HERMAN VON HELMHOLTZ
1876

2. living organisms were powered by an innate "vital force" rather than energy. Helmholtz
disproved this by stimulating a frog's nerve first near a muscle and then farther away; when
the stimulus was farther from the muscle, it contracted just a little slower. After a few
simple calculations Helmholtz announced the impulse velocity within the nervous system
to be about one-tenth the speed of sound.
3. In 1863, Intrigued by the inner workings of the sense organs, Helmholtz went on to study
the human ear. Being an expert pianist, he was particularly concerned with the way the ear
distinguished pitch and tone. He suggested that the inner ear is structured in such a way as
to cause resonations at certain frequencies. This allowed the ear to detect similar tones,
overtones, and timbres, such as an identical note played by two different instruments.
Helmholtz published ‘Sensations of Tone’, once again demonstrating his interest in the
physics of perception. Helmholtz invented the ‘Helmholtz resonator’ to identify the various
frequencies or pitches of the pure sine wave components of complex sounds containing
multiple tones.
FIG 3 HELMHOLTZ RESONATOR
Helmholtz showed that different combinations of resonator could mimic vowel sounds.
Helmholtz had transmitted multiple frequencies by wire whereas, in reality, electrical
power was used only to keep the resonators in motion.
REFERENCES:
 http://psychology.jrank.org/pages/300/Hermann-Von-Helmholtz.html
 http://study.sagepub.com/sites/default/files/Hermann%20von%20Helmholtz.pdf
 https://www.sciencedirect.com/science/article/pii/B0080430767001376