PSY 3360 / CGS 3325
Historical Perspectives
on Psychology
Minds and Machines since 1600
Dr. Peter Assmann
Summer 2016
Deductive reasoning
Some key concepts
• Rationalism vs. empiricism
• Induction and deduction
• Free will vs. determinism
• Dualism vs. monism
• Mind-body problem
• Nativism
Inductive reasoning
• All men are mortal. (major premise)
• Socrates is a man. (minor premise)
• Socrates is mortal. (conclusion)
• This crow is black
• Every crow I have ever seen is black.
• Therefore: All crows are black.
• If the premises are true, then the conclusion
must be true, following the rules of logic
• In this example, a universal statement is
induced from individual observations. This
mode of reasoning cannot guarantee the truth
of the conclusion.
The British Empiricists
David Hume (1711-1776)
• Francis Bacon (1561-1626)
• Thomas Hobbes (1588-1679)
• John Locke (1632-1704)
• George Berkeley (1685-1753)
• David Hume (1711-1776)
• Radical skepticism
 style of inquiry
 psychological feeling
 response to Descartes
• Epistemology
 Statements of fact
 Relations of ideas
• Causality
1
Epistemology
• No statement of fact can ever be proved by
reasoning a priori. The only way to
establish the truth of a factual statement is
through experience.
Theory of meaning
• How can words stand for ideas?
1. they can be derived from empirical facts
(matters of fact)
2. they can be derived analytically, based
on the relationships among the ideas they
contain (relations of ideas)
Theory of causality
• What creates the link between cause and effect?
1. no necessary link between cause and effect
2. habitual association
3. feeling of necessity (natural belief)
Free will vs. determinism
• Hume’s view of free will is linked to his
theory of causality
– there is no logical necessity in events
– the feeling of necessity is an illusion, a
psychological projection based on the
association of ideas
– This illusion has great utility for everyday life.
Immanuel Kant (1724-1804)
• born in Königsberg (now
Kaliningrad, in Russia)
• never left his home town,
never married; taught at
the University of
Königsberg
• attracted students and
researchers from all over
Europe and Britain
2
Epistemology
• a priori: a way of gaining knowledge without
appealing to any particular experience(s). This
method is used to establish transcendental and
logical truths.
• a posteriori: a method of acquiring knowledge by
appealing to some particular experience(s). This
method is used to establish empirical facts and
hypothetical truths.
Key concepts
• Kant regarded mathematics as a priori and synthetic
because it depends on the pure intuitions of the
elements of time and space.
Epistemology
• analytic statement: a statement or item of
knowledge that is known to be true solely because
of its conformity to rules of logic.
• synthetic statement: a statement or item of
knowledge that is known to be true because of its
connection with some intuition.
• In an analytic judgment, the predicate is
contained in the subject: For example,
"Triangles have three sides."
• The truth of this statement is determined
by an analysis of the subject.
• In a synthetic judgment, the predicate
adds to or expands the subject : For
example,
"Triangles were the earliest figures to be
discovered in geometry."
analytic
• The truth of such a statement cannot be
known by an analysis of the subject.
synthetic
a priori
a posteriori
“Triangles have
three sides”
(none)
Kant’s
categories;
mathematics
“Some birds
fly south in
winter”
3
Critique of Pure Reason
• Transcendentalism: philosophical view
that there is a form of knowledge derived
from synthetic a priori judgments.
• Objects in the real world are fundamentally
unknowable. They provide the raw material
from which sensations are derived.
Critique of Pure Reason
• Space and time exist only as part of
the mind, as "intuitions" by which
perceptions are measured and judged.
• In addition to these intuitions, Kant
proposed that a number of a priori
concepts, called categories, also exist.
Kant's categories
• There are four main categories with 3 subcategories each, for a total of 12:
quantity
unity, plurality, totality
quality
reality, negation, limitation
relation
substance & accident, cause & effect, reciprocity
modality
possibility, existence, necessity
Noumena and phenomena
• Noumena: “things-in-themselves”–
objects in a pure state independent of
human experience; cannot be known
directly.
• Phenomena: anything experienced is
transformed by the mind into a subjective
phenomenon (i.e., conditioned by space,
time and the categories).
Kant's categories
• Kant’s categories include the most general
concepts of human experience.
• These provide a conceptual framework in
terms of which all objects are analyzed.
• The objects of empirical knowledge
(everything we experience) is “filtered”
through the categories.
Ethical and moral philosophy
• Kant's ethical system is based on the belief that
reason is the final authority for morality.
• Actions of any sort, he believed, must be
undertaken from a sense of duty dictated by
reason.
• No action performed for expediency or solely
in obedience to law or custom can be regarded
as moral.
4
Ethical and moral philosophy
• Kant described two types of commands
given by reason: the hypothetical
imperative, which dictates a given course
of action to reach a specific end; and the
categorical imperative, which dictates a
course of action that must be followed
because of its rightness and necessity.
Kant’s theory of causality
 Hume's rejection of causality
Ethical and moral philosophy
• The categorical imperative is the basis of
morality and was stated by Kant in these
words:
"Act as if the maxim of your action were to
become through your will a general natural
law."
Kant’s theory of causality
 Kant’s answer: Causality is
 Co-occurrence of events
 fundamental to science and human knowledge
 Habitual association
 a relationship not based on observation
(synthetic a posteriori) or logic (analytic a
priori)
 (Illusory) feeling of necessity
 imposed by the structure of the human mind
(synthetic a priori)
Kant’s psychological theory
 Noumena and phenomena
 Space, time and the 12 categories of
experience
 Perception is an active process
 The mind actively participates in the
Kant’s contributions to psychology
 Synthesis of empiricism and rationalism
 Perception is an active process
 The mind makes an active contribution to our
experience of reality
 The mind can be studied, but only by
introspection, not direct observation.
construction of reality
5
Kant’s contributions to psychology
 Kant believed that mental phenomena could
not be studied empirically because they
(1)
lacked spatial dimensions
(2)
were too transient
(3)
could not be experimentally manipulated
(4)
could not be described mathematically.
19th century developments: Germany
• Increased interest in sensation and perception
• New, emerging view of the relationship between
mind and body:
– higher cognitive functions are mediated by the central
nervous system.
– perception can be measured and mapped out using
methods developed in other branches of science.
– the idea of a threshold: the minimum amount of energy
required to elicit a change in perception.
19th century developments
Emerging viewpoints
1. Higher cognitive functions are mediated by the
central nervous system.
2. Sensation and perception can be measured and
mapped out using methods developed in other
branches of science.
3. Concept of a threshold, the minimum amount of
energy needed to elicit a change in perception.
4. Elaboration of the laws of association.
History of neuroscience
• Relationship between mind and body
– Are the mind and body (brain) separate entities
controlled by different principles (dualism) or
are they integrated (monism)?



Changing views on the relationship between
mind and body
Improved techniques for studying perception
Developments in physiology
1. Distinction between sensory & motor nerves
2. Doctrine of specific nerve energies
History of neuroscience
• Localization of function
– Relationship between psychological functions
and specific structures in the brain and nervous
system
– Are areas of the brain specialized for separate
functions (localized) or does the brain operate
as an undifferentiated whole (holistic view)?
6
Early theories
History of neuroscience
• Localization of function
– Descartes: the mind could not be localized in
the brain because its structures were paired;
how could consciousness occupy two places at
the same time?
• Aristotle (384–322 BC) – Believed the heart, not the brain, was the organ of thought
• Galen (130‐200 AD)
– Recognized the brain’s role in sensation and motor control; animal spirits
Renaissance period
• René Descartes (1596‐1650) – Fluid (hydrodynamic) theory of transmission of animal spirits – Reflex theory
– Dualist view of mind and body
– At a single location (pineal gland) messages are transmitted between mind and body
Aristotle
(384–322 BC) René Descartes (1596-1650)
• Fluid (hydrodynamic) theory of
transmission of animal spirits
• animal spirits responsible for the flow of
sensory and motor information in the body
• Reflex theory
• Dualist view of mind and body with pineal
gland as the control center
Thomas Willis (1621-1675)
• John Locke’s teacher
• detailed brain anatomy
• gray matter & white
matter
• Cerebral cortex has
convolutions; blood vessels
• Anatomy of subcortical
centers
Thomas Willis
7
Franz Gall
(1758-1828)
Physiognomy and phrenology
 Gall postulated that the cerebral
cortex serves the highest level of
brain function.
 Analyzed character traits and
skulls of famous people and
criminals.
 Generated a list of 27 faculties
(including sex drive, maternal
behavior, aggression, etc).
 Launched new “science” called
phrenology.
• Phrenology: surface of
the skull mirrors the
exaggeration of functional
areas in the cortex.
• Bumps on the skull are
associated with faculties
that are prominent in
individuals.
• Gall’s work foreshadows
the idea of localization of
function.
Paul Flourens (1794-1867)
• Critic of the phrenology movement
• Ablation studies of animals
• Brain lesion studies suggested to Flourens that the
cerebral hemispheres function together as a single
unit
• Launched debate over localization of function
Johannes Müller (1801-1858)
• Doctrine of specific nerve energies
– sensory nerves can be stimulated in different
ways to produce the same characteristic energy
resulting in the same sensation.
– Rejected theory of animal spirits; hypothesized
that nerve impulses were electrical; hence, too
rapid to be measurable.
19th century developments
• Luigi Galvani (1737‐1798)
• Electrical charge applied to the spinal cord of a frog results in leg muscle spasms
• Information in the nervous system is transmitted via electric current generated by organic tissues
8
19th century developments
• Johannes Purkinje (1787‐1869)
• First to describe nerve cells
19th century developments
Gustav Fritsch (1838‐1907) Eduard Hitzig
(1838‐1927) • Discovered large branching nerve cells (“Purkinje cells”) in the cortex
Drawing of Purkinje cells from pigeon cerebellum by Santiago Ramón y Cajal, 1899
Pierre Paul Broca (1824-1880)
• cranial damage and lesions as a means of
studying localization of cerebral function in
humans.
• Electrical current applied to different regions of a dog’s motor cortex (“motor strip”) produce specific muscular contractions
• Localization of motor function
Pierre Paul Broca (1824-1880)
• Broca’s area: frontal lobe of the left hemisphere
• Hemispheric lateralization of function
• “language center” ?
• In 1861 Broca presented a case study of a man
with normal cognitive functions in all respects
except that he no longer possessed the ability to
speak (aphasia).
• When the patient died, Broca performed an
autopsy and revealed a lesion in the middle part
of the frontal lobe of the left hemisphere.
Carl Wernicke (1848-1904)
 In 1874, Carl Wernicke
described a different
pattern of language
breakdown with injury
to the temporal lobe of
the left hemisphere,
which he described as
sensory aphasia.
Aphasia – disorders of language
Pierre Paul Broca
Carl Wernicke
(1824-1880)
(1848-1904)
• Case study of a stroke
patient with a lesion in the
left frontal lobe (now called
Broca’s area) who could
understand language but
could not speak
• Case study of a patient with
lesion in the temporalparietal lobe region (now
called Wernicke’s area) who
could speak fluently but
made no sense
• Localization of function
• Hemispheric lateralization
9
19th Century Neuroscience
• Sensory and motor nerves
– Bell & Magendie
– two distinct types of nerves:
– ventral roots of spinal cord
contain motor nerves.
– dorsal roots contain sensory
nerves.
– differentiation of function
Johannes Müller (1801-1858)
• Doctrine of specific nerve energies
– sensory nerves can be stimulated in different
ways to produce the same characteristic energy
resulting in the same sensation.
– Rejected theory of animal spirits; hypothesized
that nerve impulses were electrical; hence, too
rapid to be measurable.
Hermann Ludwig Ferdinand
von Helmholtz (1821-1894)
• Life and times
• Medicine, physiology,
mathematics, physics
• Rationalism and empiricism
• Vitalism and mechanism
Vitalism vs. Mechanism
• Vitalism: living things share a
vital force that cannot be
explained by the physical
sciences (Müller)
• Mechanism: same laws apply
Johannes Müller
to living and non-living things
1801-1858
(Helmholtz)
Hermann Ludwig
Ferdinand von
Helmholtz
(1821-1894)
Vitalism vs. Mechanism
• Vitalism: living things share a vital
force that cannot be explained by
the physical sciences (Müller)
• "Willed behavior is instantaneous."
• Mechanism: same laws apply to
living and non-living things
(Helmholtz)
Johannes Müller
1801-1858
• Principle of conservation of energy
10
Helmholtz’ studies of nerve conduction
 Measured speed of
nerve conduction
using a modified
galvanometer
• Mild electrical
stimulation of a
frog’s leg produces
muscle twitches.
• Conductance rate:
~90 feet/sec
Hermann Ludwig Ferdinand von
Helmholtz (1821-1894)
Speed of nerve conduction
• Reaction times in humans: subjects pressed a
button in response to tactile stimulus
 Response times ~165-330 feet per second
 Nerve transmission rate is finite (relatively
slow)
Helmholtz' theory of perception
• Perception = active, unconscious,
automatic, logical processes
• Unconscious inference
• Role of learning and memory in
transforming sensory information
Helmholtz (1850) demonstrated
experimentally in both animals
and humans that the speed of
nerve transmission was not
instantaneous, nor even close to
the speed of light, but in fact
only around 50 meters per
second (less than 100 mph).
Young-Helmholtz theory of color vision
• Newton (1672) – wavelength
• Trichromatic theory: human
color vision involves three color
receptors (RGB)
• Color receptors (cones) in the
retina
• Laws of color mixing
• Color blindness
– Experiments with distorted lenses
– Motion pictures– succession of still
images
– Railroad tracks are parallel but seem
to converge in the distance
Munsell color system
Hue: dominant wavelength
Value: brightness
Chroma: purity
11
Auditory theory
Theory of hearing
Helmholtz proposed that the cochlea, part of the inner
ear, is responsible for frequency analysis in hearing.
 Helmholtz proposed that the basilar membrane, housed
within the cochlea of the inner ear, responds selectively
to the different frequency components of sound waves.
low frequencies
high frequencies
Place (resonance) theory of hearing
Frequency analysis
• Fourier analysis: mathematical decomposition
of any complex waveform into simple sinusoidal
components
• Cochlear fibers vary in length
• Tuned to vibrate at specific
frequencies
• Different positions along the
cochlea respond selectively
to different frequencies to
determine what pitch we hear
Complex
wave
Joseph Fourier
(1768-1830)
Frequency analysis
• Fourier synthesis: any complex waveform
can be reconstructed (synthesized) from sine
waves.
Simple
sine
waves
Response to a low-frequency sound
Simple
sine
waves
Joseph Fourier
(1768-1830)
Vowel
sound
12
Frequency and pitch
Response to a high-frequency sound
• Physical property: Frequency
• Psychological property: Pitch
Sine wave
On the sensations of tone
 Helmholtz invented the double
siren to produce tones of any
specified frequency.
 He used this device to map out
the mathematical relationship
between frequency and pitch.
Frequency and pitch
Frequency
• Psychological property:
Pitch
• Physical property:
Sine wave
Musical tone
“First of all, what is a musical tone? Common
experience teaches us that all sounding bodies are
in a state of vibration … The sound becomes a
musical tone, when such rapid impulses recur with
perfect regularity and in precisely equal times.
Irregular agitation of the air generates only noise.
The pitch of a musical tone depends on the
number of impulses which take place in a given
time; the more there are in the same time the
higher or sharper is the tone.” Helmholtz, 1865
Complex wave
Complex wave
Helmholtz’s contributions
•
•
•
•
•
•
Principle of conservation of energy in biology
Studies of the rate of nerve conduction
Perception and unconscious inference
Trichromatic theory of color vision
Place theory of hearing
Theory of musical pitch
13
Pitch Perception
Sine wave
Intensity
 Complex sounds have
many components; the
activation produced by
the lowest one (called
the fundamental
frequency) determines
the pitch.
Frequency
Frequency
Frequency analysis
Sine wave
Problem of the missing fundamental
Complex wave
Original
100 200 300 400
Frequency (in cycles/sec, or Hz)
Intensity
Intensity
Frequency
Frequency
Helmholtz’ studies of nerve conduction
Problem: how to separate nerve propogation
speed from other factors?
 Helmholtz proposed that nonlinear interaction in the
cochlea re-introduces the missing fundamental.
(We now know this hypothesis was incorrect).
Helmholtz’ studies of nerve conduction
• Compared reaction times at different body locations
• By subtracting one reaction time from another, he estimated that
nerve impulses travel at ~165-330 feet per second
 Telegraph machine metaphor
1.
Signal travels through sensory nerves
2.
Response travels through motor nerves to the
muscles
3.
Central nervous system ‘processes of
perceiving and willing’
Missing
fundamental
 Simple reaction time in humans: subjects pressed a
button in response to tactile stimulus
 Nerve propogation time in humans
•
Complex wave
Intensity
 Helmholtz proposed
that the location
(place) of maximum
vibration along the
basilar membrane
determines the pitch
we perceive.
Pitch Perception


Nerve impulses travel about 2x as fast in humans as in frogs
Mental processes take time; they can be measured.
Invented by Hipp
in the 1860s
14
Franciscus Cornelius Donders
(1818-1889)
Other developments in neuroscience
Helmholtz (1850)
demonstrated experimentally in
both animals and humans that
the velocity of nerve impulses
was not instantaneous, nor even
close to the speed of light, but
in fact only about 50 meters per
second (less than 100 mph).
• Dutch physiologist
• 15 years after Helmholtz’
study, Donders measured
simple reaction time to
visual stimuli
Franciscus Cornelius Donders
Franciscus Cornelius Donders
• Next Donders presented a series of stimuli
and asked subjects to respond to only one,
specified beforehand.
• Subtractive method: the time
taken to discriminate the complex
stimulus minus the time to
discriminate the simple stimulus.
• The extra time provided a measure of the
mental act of discrimination.
A
B
C
D
E
A
Response
B
C
D
E
Response
Franciscus Cornelius Donders
• Choice reaction time: several
different stimuli are presented
and the response to each one is
different.
A
B
C
D
• The time required to make a choice
is determined by subtracting both
simple and discrimination reaction
times from the choice reaction time.
E
Stimulus:
Response:
Franciscus Cornelius Donders
A
B
C
D
E
a
b
c
d
e
Stimulus:
a
b
c
d
e
Response:
"mental chronometry"
15
19th century developments
• Johannes Purkinje (1787‐1869)
• First to describe nerve cells
• Discovered large branching nerve cells (“Purkinje cells”) in the cortex
Drawing of Purkinje cells from pigeon cerebellum by Santiago Ramón y Cajal, 1899
19th century developments
• Luigi Galvani (1737‐1798)
• Electrical charge applied to the spinal cord of a frog results in leg muscle spasms
• Information in the nervous system is transmitted via electric current generated by organic tissues
Fritsch
19th century developments
Gustav Fritsch (1838‐1907) Eduard Hitzig
(1838‐1927) Hitzig
• Electrical current applied to different regions of a dog’s motor cortex (“motor strip”) produce specific muscular contractions
• Localization of motor function
Pierre Paul Broca (1824-1880)
• cranial damage and lesions as a means of
studying localization of cerebral function in
humans.
Pierre Paul Broca (1824-1880)
• Broca’s area: frontal lobe of the left hemisphere
• Hemispheric lateralization of function
• “language center” ?
• In 1861 Broca presented a case study of a man
with normal cognitive functions in all respects
except that he no longer possessed the ability to
speak (aphasia).
• When the patient died, Broca performed an
autopsy and revealed a lesion in the middle part
of the frontal lobe of the left hemisphere.
16
Carl Wernicke (1848-1904)
 In 1874, Carl Wernicke
described a different
pattern of language
breakdown with injury
to the temporal lobe of
the left hemisphere,
which he described as
sensory aphasia.
Aphasia – disorders of language
Pierre Paul Broca
Carl Wernicke
(1824-1880)
(1848-1904)
• Case study of a stroke
patient with a lesion in the
left frontal lobe (now called
Broca’s area) who could
understand language but
could not speak
• Case study of a patient with
lesion in the temporalparietal lobe region (now
called Wernicke’s area) who
could speak fluently but
made no sense
• Localization of function
• Hemispheric lateralization
Other developments in neuroscience
Emil du Bois-Reymond (1818-1896)
Galvani (1780)
discovered that a frog’s
leg would twitch when
the inside and outside of
the muscle were
connected in series with
two different metals.
• du Bois-Reymond discovered the action
potential in 1848
• An action potential (or nerve impulse) is a
pulse-like wave of voltage that travels along
the axon of a neuron.
http://bcs.whfreeman.com/thelifewire/content/chp44/4402s.swf
Other developments in neuroscience

Fritsch and Hitzig (1870)
showed that electrical
stimulation of regions of
the cortex in dogs produced
specific responses of
individual muscle groups
(motor strip).
Later developments in neuroscience
 Lashley (1890-1959) coined the term
equipotentiality to describe the capacity of an
intact part of the brain to take over the
(memory) functions of an damaged portion.
17
“engram”
1. Mass Action
2. Equipotentiality
Karl Lashley
Wilder Penfield (1891-1976)
• Brilliant neurosurgeon; leading authority on
epilepsy
• Electrical stimulation of the cerebral cortex
in awake patients (prior to surgery) could
produce complex perceptions or motor
actions
• homunculus (cartoon map of motor cortex)
18