The Science of Psychology

What is Psychology? Science of behaviour Science of behaviour Mind? Brain? Mind? Brain? Behaviour is observable Behaviour is observable

Steps in Explaining Behaviour Describe Describe –categorize, measure, etc. Find cause Find cause –causal events

Roots of Psychology A relatively recent discipline A relatively recent discipline Ancient explanations Ancient explanations Philosophy Philosophy Physiology Physiology

History of Psychology Trephination Trephination –from 40,000 years before present to... –today! Mental illness, head trauma, cultural practices Mental illness, head trauma, cultural practices

Classical Period Philosophical roots Philosophical roots Consciousness Consciousness –Minds control behaviour Animism Animism –Living and non-living things possess spirits

Philosophical Groundwork Questions about mind Questions about mind Ancient Greeks Ancient Greeks –Aristotle –Associationism »Contiguity, similarity, contrast

René Descartes ( ) Mathematician, philosopher, physiologist Mathematician, philosopher, physiologist Cartesian dualism Cartesian dualism Mind/body dualism Mind/body dualism

Cartesian Dualism Reflex actions Reflex actions Voluntary actions Voluntary actions Involuntary actions Involuntary actions

Of Mice and Men Only humans have mind Only humans have mind Animals are automatons Animals are automatons –Involuntary actions only

Problem with Cartesian Dualism Interactionism theory Interactionism theory Consciousness and physical action Consciousness and physical action –Qualitatively separate Problem with interactionism Problem with interactionism –How can non-physical mind interact with and control physical body?

Occasionalism Gérand de Cordemoy (d. 1684) Gérand de Cordemoy (d. 1684) –God intervenes to control all –An extreme interpretation

Double-aspect Theory Benedictus de Spinoza ( ) Benedictus de Spinoza ( ) Mental & physical are different aspects of same substance Mental & physical are different aspects of same substance –God is the universal substance

Psycophysical Parallelism Wilhelm Leibniz ( ) Wilhelm Leibniz ( ) –Historian, mathematician, philosopher, scientist, diplomat Rejected interactionism Rejected interactionism –Two such dissimilar elements can’t interact Rejected occasionalism Rejected occasionalism –No third entity can cause such different effects (Deus ex machina) Proposed Parallelism Proposed Parallelism –Mind & body exist in harmony

Immaterialism George Berkeley ( ) George Berkeley ( ) Denies mind/body distinction Denies mind/body distinction Body is only a perception of the mind Body is only a perception of the mind

Materialism Julien Offray de la Mettrie ( ) Julien Offray de la Mettrie ( ) L’homme machine L’homme machine Extended Descartes’ animal automata concept to humans Extended Descartes’ animal automata concept to humans Mental events dependent on body Mental events dependent on body Voluntary, involuntary and instinctual processes only differ in physical complexity Voluntary, involuntary and instinctual processes only differ in physical complexity

Materialism Pierre Jean Georges Cabonis ( ) Pierre Jean Georges Cabonis ( ) –Rapports du physique et du moral de l’homme (1802) »“...to have an accurate idea of the operations from which thought results, it is necessary to consider the brain as a special organ designed especially to produce it, as the stomach and the intestines are designed to operate the digestion...” –The brain is the mind Other Materialists Other Materialists –e.g., James Mill ( )

Materialism Question If the only difference between voluntary, involuntary, and instinctual behaviour is the underlying complexity of the physical structure, should robotic devices be considered to be alive? If the only difference between voluntary, involuntary, and instinctual behaviour is the underlying complexity of the physical structure, should robotic devices be considered to be alive?

Is this robot alive?

How about this one?

John Locke ( ) Contrasted outer and inner senses Contrasted outer and inner senses Questioned the limits of knowledge Questioned the limits of knowledge Empiricism Empiricism Primary & secondary qualities Primary & secondary qualities

Empiricism Knowledge through experience Knowledge through experience Tabula rasa Tabula rasa –Born with no knowldge British Empiricists British Empiricists –Philosophical school of thought

Primary and Secondary Qualities Primary Primary –Inseparable from an object and simply perceived by senses (e.g., solidity) Secondary Secondary –Produced by the perceiver of an object, so not an aspect of the object itself (e.g., colour, sound) Simple ideas combine to form complex ones Simple ideas combine to form complex ones

Nativism Some ideas innate Some ideas innate Some ideas gained through experience Some ideas gained through experience Composite theory Composite theory

Could Psychology be a Science? Immanuel Kant ( ) Immanuel Kant ( ) –No! Two Problems: Two Problems: –Psychological processes vary only in time; can’t be described mathematically –Psychological processes are internal and subjective

Responses to Kant Johan Herbart Johan Herbart Mental entities vary in time and intensity Mental entities vary in time and intensity Generated mathematical models Generated mathematical models Gustav Fechner Gustav Fechner Generated scale to measure strength of a sensation Generated scale to measure strength of a sensation G. Fechner

Physiological Contribution Between 1800 and Between 1800 and Distinction of sensory & motor nerves Distinction of sensory & motor nerves Study of sensations of vision & touch Study of sensations of vision & touch Nervous system as mediator between mind and world Nervous system as mediator between mind and world

Sensory and Motor Nerves Charles Bell ( ) Charles Bell ( ) Anatomical evidence Anatomical evidence Dorsal roots: sensory Dorsal roots: sensory Ventral roots: motor Ventral roots: motor

Study of Vision and Touch Jan Purkyne ( ) Jan Purkyne ( ) –Vision –“Purkyne” effect »change in apparent luminosity of colours in dim vs bright daylight Ernst Heinrich Weber ( ) Ernst Heinrich Weber ( ) –Touch –Just noticeable difference (JND)

Nervous System as Mediator Between Mind and World Johannes Müller ( ) Johannes Müller ( ) –Doctrine of specific nerve energies »All nerves send same electrical impulse –Mind not aware of physical world directly, but of states of the nervous system –Sensory nerves specific to different senses »Suggests regional brain specialization

Nerve Impulses Hermann von Helmholtz ( ) Hermann von Helmholtz ( ) Speed of nerve impulse propagation Speed of nerve impulse propagation –~27m/sec –Led to reaction-time technique (Franciscus Donders) Also, theory of colour vision Also, theory of colour vision

Regions of the Brain Ferrier Ferrier –Extended Fritsch & Hitzig’s experiments –Mapped sensory and motor areas of cortex –Cross-species study

Regions of the Brain Paul Broca ( ) Paul Broca ( ) –Stroke patient –Speech loss –Autopsy –Left side of cerebral cortex damaged

First Psychology Laboratory, 1879 Wilhelm Wundt ( ) Wilhelm Wundt ( ) Combined philosophy and physiology Combined philosophy and physiology Principles of Physiological Psychology Principles of Physiological Psychology

Schools of Thought in Psychology

Structuralism Founded by Wilhelm Wundt Founded by Wilhelm Wundt “Science of immediate experience” “Science of immediate experience” Introspection Introspection –How does sensory information create complex perceptions?

Hermann Ebbinghaus Not a school, per se... Not a school, per se... Human memory Human memory Nonsense syllables; recorded trials to learn perfectly Nonsense syllables; recorded trials to learn perfectly Entirely empirical; no theory Entirely empirical; no theory Forgetting Curve

Functionalism William James ( ) William James ( ) Darwinian Darwinian Biological function of behaviours; focus on: Biological function of behaviours; focus on: –Study of mental operations, not structures –Mental processes studied in context of animal’s biology –Relation between environment and animal’s responses to environment

Psychodynamic Theory Sigmund Freud ( ) Sigmund Freud ( ) Theory of personality Theory of personality Case studies Case studies Ego, superego, and id Ego, superego, and id

Behaviourism Edward Thorndike ( ) Edward Thorndike ( ) –Law of Effect Ivan Pavlov ( ) Ivan Pavlov ( ) –Classical conditioning John Watson ( ) John Watson ( ) –Only study observable behaviours B.F. Skinner ( ) B.F. Skinner ( ) –Operant behaviour

Gestalt Psychology Max Wertheimer ( ) Max Wertheimer ( ) Studied cognition of perception Studied cognition of perception The whole is more than the sum of its parts The whole is more than the sum of its parts In contrast to Structuralism In contrast to Structuralism

Humanistic Psychology Human nature goes beyond environmental influences Human nature goes beyond environmental influences Emphasizes human experience, choice, creativity, etc. Emphasizes human experience, choice, creativity, etc. Reaction against Behaviourism and psychoanalysis Reaction against Behaviourism and psychoanalysis Psychotherapy Psychotherapy

Cognitive Psychology Reaction against Behaviourism Reaction against Behaviourism Information processing Information processing –Computer analogy Memory Memory

Cognitive Neuroscience Neurobiology and cognition Neurobiology and cognition Technological advances Technological advances –fMRI, PET, human genome project, etc.

Modern Fields of Psychology

Physiological psychology Physiological psychology Psychophysiology Psychophysiology Comparative psychology Comparative psychology Behaviour analysis Behaviour analysis Behaviour genetics Behaviour genetics Cognitive psychology Cognitive psychology Experimental neuropsychology (cognitive neuroscience) Experimental neuropsychology (cognitive neuroscience)

Developmental psychology Developmental psychology Social psychology Social psychology Personality psychology Personality psychology Cross-culture psychology Cross-culture psychology Clinical psychology Clinical psychology

Applied Psychology Clinical neuropsychologists Clinical neuropsychologists Health psychologists Health psychologists School psychologist School psychologist Consumer psychologists Consumer psychologists Community psychologists Community psychologists Organizational psychologists Organizational psychologists Engineering psychologists (ergonomists) Engineering psychologists (ergonomists)