Chapter 3: Physiological Influences on Psychology

1. Chapter 3: Physiological Influences on Psychology

2. The importance of the human observer • Measurement errors • 1795: Maskelyne (England's royal astronomer) and his assistant, Kinnebrook, recorded different times for a star to travel from point to point

3. 20 years later… • Bessel reviewed the above incident • Reasoned that the difference in times was due to individual differences not under personal control • Why important? • Cognitive processes occur over a definable time period • Scientists forced to acknowledge that the observer is important (personal traits and perceptions) • Scientists began to focus on the physiological processes involved in sensing and perceiving

4. Early physiology • Luigi Galvani (1737 – 1798) • Suggested that the nerve impulse is electrical • By mid 19th century accepted as fact

5. Early physiology • Early 1800s: • Sensory and motor information travels in separate pathways • i.e., info is only sent in one direction

6. Early physiology • Johannes Muller (1801-1858) • Dominant advocate of experimental method • Specific energies of nerves doctrine • stimulation  specific nerve  sensation • Importance: • Lead to the idea that different areas of the brain have different functions • Localization of functions http://tangibleinteraction.files.wordpress.com/2007/05/senses-lowres.jpg

7. Research on the nervous system • Franz Josef Gall (1758-1828) • Phrenology • the correlation of bumps on the skull with personal traits • However, Flourens showed that underlying brain did not follow contours of skull http://www.uh.edu/engines/phrenologicalchart.jpg

8. Research on brain functions • Pierre Flourens (1794-1867) • Extirpation: Lesiona given part of an animal’s brain and observe the resulting behavior changes. • Cerebrum: Higher mental processes: • Midbrain: Visual and auditory reflexes • Cerebellum: Coordination • Medulla: Heartbeat, respiration

9. Research on brain functions • Paul Broca (1824-1880) • Clinical method: examine damaged brain structures in humans after death • Broca’s area: • the speech center in the 3rd frontal convolution of the left hemisphere of the cerebral cortex • when damaged, person could not produce speech

10. Research on brain functions • Electrical stimulation: pass a weak electrical current into animal’s brain to see motor responses

11. Research on the nervous system • Santiago Ramón y Cajal (1852-1934) • Discovered the direction of travel for brain and spinal cord nerve impulses (Nobel prize) • Nervous system comprised a vast array of independent, separate nerve cells.

12. Importance of physiologists • Countered idea that psychology could never be a science … • by making it possible to measure mental experience … • with precise and elegant techniques of measurement. • In other words, they revealed a way to investigate the mind-body relationship

13. http://www.mrcophth.com/Historyofophthalmology/indirect.jpg The Beginnings of Experimental Psychology • Hermann von Helmholtz (1821– 1894) • Neural impulse • Vision • Audition

14. The Beginnings of Experimental Psychology • Gustax Fechner (1801 – 1887) • Relative intensities • Absolute threshold • Differential threshold

15. method of limits

16. The Beginnings of Experimental Psychology • Ernst Weber (1795 – 1878) • Just Noticeable Differences No 100 lbs 101 lbs Yes 100 lbs 102 lbs

17. The Beginnings of Experimental Psychology • Ernst Weber (1795 – 1878) • Two-point thresholds: • Test in which two different points were stimulated on a person’s skin • The objective was to discover how far the two points had to be away from each for the person to notice that there were two points • First systematic experimental demonstration of the concept of threshold • Also demonstrated individual differences between people

18. Many of these physiologists were German… • Why? • Location where physiology was firmly established • Tendency to use inductive rather than deductive reasoning • Temperament of German people • Broader definition of science • Greater opportunities to make a living as a scientist

19. The formal founding of psychology • British empiricists • Subject matter: study mind and behavior • German physiologists • Methods: experimentation • General zeitgeist: encouraged melding of philosophy and physiology