Lesson 9 - Key Figures in Physiology & Psychophysics

Immanuel Kant

Believed that people form their own phenomenal world through perception. Suggested that perception may differ between individuals due to differences in their sensory systems and intellectual capacities.

Impact on Psychology (Immanuel Kant)

Inspired the exploration of the nervous system as a foundation for perception. His ideas encouraged empirical investigation into how the senses and nerves mediate our experience of the world, laying philosophical groundwork for experimental psychology.

Johannes Müller

Vitalist - believed life processes couldn't be explained solely by physical or chemical laws.

Impact on Psychology (Johannes Müller)

Introduced the Doctrine of Specific Nerve Energies - each sensory nerve carries a specific kind of sensation, regardless of how it is stimulated. This idea helped establish that perception is tied to the type of nerve activated, not the stimulus itself.

Hermann von Helmholtz

Materialist - rejected vitalism; believed all physiological processes can be explained through physical and chemical laws.

Impact on Psychology (Hermann von Helmholtz)

Measured nerve conduction speed, developed the Trichromatic Theory of Color Vision (with Young), and proposed the Resonance Place Theory of Auditory Perception. Helped move psychology toward a more empirical and experimental science.

Ewald Hering

Opposed Helmholtz's color theory; focused on opponent processes in vision.

Impact on Psychology (Ewald Hering)

Developed the Opponent-Process Theory of Color Vision - proposed three pairs of opposing receptors (red-green, yellow-blue, black-white). Explained phenomena like afterimages and perception of gray, influencing modern theories of vision.

Christine Ladd-Franklin

Evolutionary perspective on vision.

Impact on Psychology (Christine Ladd-Franklin)

Proposed an evolution-based theory of color vision: black-and-white vision evolved first, followed by color. Suggested that parts of the eye still reflect this evolutionary path. Considered a pioneer in evolutionary psychology.

Franz Joseph Gall

Believed in faculty psychology - different brain regions control different mental functions.

Impact on Psychology (Franz Joseph Gall)

Founded Phrenology, which mapped traits to skull shapes. While now discredited, phrenology was an early attempt to link brain structure with behavior and inspired future brain research.

Gustav Fechner

Influenced by Naturphilosophie and Spinoza's dual-aspect theory (mind and body as two aspects of the same reality). Opposed strict materialism.

Impact on Psychology (Gustav Fechner)

Founded psychophysics, which quantified the relationship between physical stimuli and mental sensation. Created Fechner's Law, formalizing the idea that sensation increases logarithmically with stimulus intensity. Also contributed to experimental aesthetics.