Chapter 8: Physiology and Psychophysics

PSYCH 304

Who were the astronomer and assistant involved in the 1795 incident that led to the study of individual differences in reaction time?

Astronomer Nevil Maskelyne and his assistant David Kinnebrook.

What did German astronomer Friedrich Bessel speculate was the reason for the discrepancy in star observation times between Maskelyne and Kinnebrook?

He speculated the error was due to individual differences among observers, not incompetence.

What method was developed by Friedrich Bessel to correct for systematic differences in reaction times among observers?

The calculation of 'personal equations' to equate different observers' reaction times.

The work of _ provided the link between the questions of philosophy and the soon-to-be science of psychology.

physiologists

What is the Bell-Magendie law?

The principle that sensory nerves enter the posterior (dorsal) roots of the spinal cord and motor nerves emerge from the anterior (ventral) roots.

What was the significance of the Bell-Magendie law for understanding the nervous system?

It demonstrated that sensory and motor functions are mediated by different anatomical structures and nerves.

Who are the two physiologists credited with the discovery of the distinction between sensory and motor nerves, leading to the law named after them?

Charles Bell and François Magendie.

What concept did Johannes Müller devise that expanded upon the Bell-Magendie law?

The doctrine of specific nerve energies.

What is the core principle of the doctrine of specific nerve energies?

Each sensory nerve, no matter how it is stimulated, produces a characteristic sensation or 'energy'.

According to the doctrine of specific nerve energies, what sensation would result from stimulating the optic nerve with pressure or electricity?

A visual sensation (light).

What was the most significant implication of Müller's doctrine for psychology?

That our sensations are determined by the nature of our central nervous system, not the physical stimulus itself.

Müller's doctrine implies that we are never conscious of objects in the physical world directly, but rather conscious of what?

Various sensory impulses in the brain linked to those real objects.

What did Johannes Müller call the concept that each sense organ is maximally sensitive to a certain type of stimulation (e.g., eye to light waves)?

Specific irritability, later referred to as adequate stimulation.

Hermann von Helmholtz, along with several fellow students, signed an oath against what physiological belief held by their teacher Johannes Müller?

Vitalism.

What is vitalism?

The belief that life cannot be explained by physical and chemical processes alone and involves a non-physical 'life force'.

What is the materialist philosophy that Helmholtz embraced?

The belief that living organisms are complex machines consisting of only material substances, governed by physical and chemical laws.

What principle did Helmholtz apply to living organisms, demonstrating that food and oxygen consumption accounted for the total energy an organism expended?

The principle of conservation of energy.

How did Helmholtz measure the rate of nerve conduction, refuting Müller's claim that it was too fast to measure?

He stimulated a frog's motor nerve at different distances from the muscle and measured the difference in reaction times.

What was the significance of Helmholtz's research on the rate of nerve conduction?

It showed that nerve impulses are measurable and relatively slow, supporting a physical-chemical explanation of nervous system function.

According to Helmholtz, what are the raw elements of conscious experience provided by the physiological apparatus?

Sensations.

According to Helmholtz, what are sensations after they are given meaning by one's past experiences?

Perceptions.

What process did Helmholtz propose to explain how past experience converts a sensation into a perception?

Unconscious inference.

According to Helmholtz's concept of unconscious inference, how does one perceive depth from the slightly different images on the two retinas?

Previous experience with such retinal disparity causes the unconscious inference of depth.

How did Helmholtz's view of how sensory information is transformed differ from Kant's?

For Kant, innate faculties of the mind transform sensory data; for Helmholtz, past experience transforms it.

What is the name of the theory of color vision proposed by Thomas Young and later supported with experimental evidence by Helmholtz?

The Young-Helmholtz theory of color vision (or trichromatic theory).

The Young-Helmholtz theory postulates the existence of three types of color receptors on the retina corresponding to which three primary colors?

Red, green, and blue-violet.

According to the Young-Helmholtz theory, how is the sensation of white light produced?

It is experienced when all three primary color receptors (red, green, blue-violet) are stimulated at once.

What theory of auditory perception did Helmholtz propose?

The resonance place theory of auditory perception.

According to Helmholtz's resonance place theory, different fibers along which membrane of the inner ear are sensitive to different sound frequencies?

The basilar membrane.

In Helmholtz's resonance place theory, short fibers on the basilar membrane respond to frequencies, while longer fibers respond to frequencies.

higher; lower

Whose view of perception sided with the nativists, contrasting with Helmholtz's empiricist view?

Ewald Hering.

What did Ewald Hering believe about space perception?

He believed space perception exists a priori, with each point on the retina automatically providing information about height, position, and depth.

What phenomenon, where the relative vividness of colors changes as a function of luminance level, is named after Jan E. Purkinje?

The Purkinje shift.

Ewald Hering's theory of color vision was based on three types of receptors on the retina, each of which could respond in what two opposing ways?

A catabolic process (tearing down) and an anabolic process (building up).

What are the three opposing color pairs in Hering's theory of color vision?

Red-green, yellow-blue, and black-white.

In Hering's theory, red, yellow, and white cause a process, while green, blue, and black cause an process.

catabolic; anabolic

How did Hering's theory explain negative afterimages, such as seeing green after staring at red?

Staring at one color depletes its corresponding process (e.g., catabolic for red), leaving only the opposite process (anabolic for green) to produce an afterimage.

Who proposed a theory of color vision based on evolutionary principles?

Christine Ladd-Franklin.

According to Christine Ladd-Franklin's evolutionary theory, what were the three stages of color vision development?

First achromatic vision, then blue-yellow sensitivity, and finally red-green sensitivity.

Ladd-Franklin's theory suggested that peripheral vision, provided by the , was more primitive than foveal vision, provided by the .

rods; cones

What is physiognomy?

The attempt to determine a person's character by analyzing their facial features, body structure, and posture.

Who was the founder of phrenology?

Franz Joseph Gall.

What were the three main claims Franz Joseph Gall made that formed the basis of phrenology?

1) Mental faculties vary between people, 2) faculties are housed in specific brain areas, and 3) faculty development corresponds to bumps or depressions on the skull.

What were some of Franz Joseph Gall's positive contributions to the study of the brain?

He suggested a relationship between cortical development and mental functioning and was the first to distinguish the functions of gray and white matter.

Who coined the term 'phrenology' and was a student of Gall who helped popularize the practice?

Johann Kaspar Spurzheim.

What was the 'mental muscle' approach to education, influenced by phrenology, called?

Formal discipline.

What is the concept of formal discipline?

The belief that mental faculties can be strengthened by practicing the traits associated with them, like studying math to improve reasoning.

What research method did Pierre Flourens use to investigate the claims of phrenologists?

Ablation (or extirpation), which involves destroying part of the brain and observing the behavioral consequences.

Did Pierre Flourens's research support or refute the claims of phrenology regarding the cortex?

It refuted them, as he concluded that the cortical hemispheres function as a unit, not as a collection of separate faculties.

What specific brain function did Paul Broca localize using the clinical method?

Speech production or articulation.

What is the clinical method, as used by Paul Broca?

It involves observing a behavior disorder in a living patient and then, after death, locating the responsible brain area via autopsy.

The brain area responsible for speech production, discovered by Paul Broca, is located in the frontal convolution of the cerebral hemisphere.

third; left

What is the name given to the cortical area responsible for speech comprehension, discovered by Carl Wernicke?

Wernicke's area.

What did Gustav Fritsch and Eduard Hitzig discover by electrically stimulating the exposed cortex of a dog?

They discovered the motor cortex, finding that stimulating specific areas elicited muscular movements on the opposite side of the body.

Who created a more detailed map of the motor cortex and also mapped cortical areas for cutaneous senses, audition, olfaction, and vision?

David Ferrier.

What is psychophysics?

The systematic study of the relationship between physical stimuli and the psychological or conscious experiences they produce.

Who is considered a pioneer in psychophysics, particularly for his research on the sense of touch and kinesthesis?

Ernst Heinrich Weber.

What is the two-point threshold, which Ernst Weber measured on different parts of the body?

The smallest distance between two points of touch at which they are sensed as two points instead of one.

What is a just noticeable difference (jnd)?

The smallest difference between two stimuli that can be discriminated or detected.

What is Weber's law?

The principle that the just noticeable difference (jnd) is a constant fraction of the standard stimulus.

Weber's law was the first statement of a systematic relationship between stimulation and a experience.

physical; psychological

Who realized the full implications of Weber's work for psychology and created the field of psychophysics?

Gustav Theodor Fechner.

What pseudonym did Gustav Fechner use to write satirical and philosophical works?

Dr. Mises.

Fechner's philosophy, which he called the 'dayview', believed that consciousness is prevalent throughout the universe, a position known as _.

panpsychism

Fechner's psychophysics aimed to prove a relationship between the mind and body, a view similar to Spinoza's philosophical position of _.

double aspectism

What is the mathematical formula for Fechner's law?

$S = k \log R$

What does Fechner's law state about the relationship between physical stimuli and mental sensations?

For mental sensations to change arithmetically, the physical stimulus must change geometrically.

What is the absolute threshold?

The lowest intensity at which a stimulus can be consciously detected.

What is the differential threshold?

The amount a stimulus magnitude must be changed before a person can detect a difference.

In the psychophysical method of _, a subject adjusts a variable stimulus until it appears equal to a standard stimulus.

adjustment (or average error)

Which psychophysical method involves presenting pairs of stimuli (one standard, one variable) and having the subject report if the variable is greater than, less than, or equal to the standard?

The method of constant stimuli.

What is the method of limits (or just noticeable differences)?

A method where one stimulus is varied and compared to a standard to determine the range of stimuli that the subject considers to be equal to the standard.

Besides psychophysics, what other field of study did Fechner create?

Experimental aesthetics.

What event marked the arguable launch of psychology as an experimental science?

The 1860 publication of Fechner's 'Elements of Psychophysics'.