Lesson 4: Physiology & Psychophysics

Lesson 4: Physiology & Psychophysics detailed flashcards ChatGPT: • Early physiological studies of the nervous system • Helmholtz and reaction times • Weber and Fechner’s laws • Relationship between mind and body

What was the early view of brain function in psychology?

Early views saw the brain as a homogenous structure responsible for thought and behavior. With time, this changed to the idea that specific regions of the brain controlled different functions — the basis for localization of function.

What is phrenology and who proposed it?

Phrenology was the theory that bumps on the skull could reveal mental traits and character. It was proposed by Franz Joseph Gall, who believed the brain had distinct regions for different faculties.

How did Pierre Flourens challenge phrenology?

Flourens used extirpation (surgical lesioning) in animals to show that destroying certain brain parts affected specific functions, but also found that multiple parts could take over for lost functions, supporting a more holistic brain view.

What is the significance of Paul Broca’s work on the nervous system?

Paul Broca discovered that damage to a specific area in the left frontal lobe (now called Broca’s area) resulted in difficulty producing speech, supporting localization of function for language production.

What was the contribution of Fritsch and Hitzig to the understanding of brain function?

Fritsch and Hitzig conducted electrical stimulation studies on dog brains and identified the motor cortex, showing that stimulating specific brain areas causes movement in particular body parts.

What technique did Gustav Fritsch and Eduard Hitzig use to map the motor cortex?

They used electrical stimulation to map the motor cortex and found specific brain regions that controlled specific muscle groups, advancing localization theory.

How did early physiological studies contribute to the shift toward scientific psychology?

They showed that mental processes had biological foundations, paving the way for psychology to move from philosophy to science, emphasizing empirical methods and experimentation.

What is Hermann von Helmholtz known for in psychology?

Helmholtz measured the speed of nerve conduction, proving that mental processes have a measurable time delay, which helped establish psychology as an experimental science.

How did Helmholtz measure reaction times?

Helmholtz measured the speed of nerve impulses by stimulating frog nerves and timing muscle reactions, calculating conduction speed at around 27 meters/second.

Why was Helmholtz’s finding on reaction times significant?

It disproved the belief that nerve impulses were instantaneous and demonstrated that mental processes could be measured, encouraging a scientific approach to psychology.

How did Helmholtz’s findings influence the development of experimental psychology?

His work showed that the mind could be studied empirically, inspiring researchers like Wundt to explore reaction time as a way to understand mental processes.

Who was Ernst Weber and what is Weber’s Law?

Weber was a physiologist who studied sensation. Weber’s Law states that the Just Noticeable Difference (JND) between stimuli is a constant proportion, not a fixed amount.

What is a Just Noticeable Difference (JND)?

A JND is the smallest detectable difference between two stimuli. According to Weber, it increases proportionally with the size of the stimulus.

What is Gustav Fechner’s contribution to psychophysics?

Fechner developed Fechner’s Law, which describes the relationship between physical stimulus intensity and perceived intensity:
S = k log R, where
S = sensation,
k = constant,
R = physical stimulus magnitude.

How did Fechner expand on Weber’s work?

Fechner used Weber’s findings to create a mathematical formula linking physical stimulus intensity and subjective sensation, founding the field of psychophysics.

What is psychophysics?

Psychophysics is the scientific study of the relationship between physical stimuli and the sensations and perceptions they produce. It was founded by Fechner.

What is the difference between Weber’s and Fechner’s laws?

Weber’s Law focuses on proportional changes (JND), while Fechner’s Law transforms those into a logarithmic scale of perceived sensation, integrating subjective experience.

Why are Weber and Fechner important in the history of psychology?

They were among the first to quantify mental processes, showing that psychological phenomena could be studied mathematically and empirically.

How did physiological studies shape the mind-body debate?

These studies showed that mental activities had physical correlates (e.g., brain areas for speech or motion), supporting a monistic view where mind and body are connected.

What is the monism vs. dualism debate?

• Dualism (Descartes): Mind and body are separate.

• Monism (supported by physiology): Mind and body are one, and mental processes result from physical brain activity.

How did Helmholtz's and others' work contribute to the monistic perspective?

By showing that nerves conduct signals and that reaction times can be measured, Helmholtz and others provided empirical evidence that mental processes are biological, favoring monism.

What was the significance of early physiological psychology for the field as a whole?

It laid the foundation for psychology as a natural science, encouraging experimental methods and objectivity, and moving away from philosophical speculation.