Some key concepts. PSY 3360 / CGS 3325 Historical Perspectives on Psychology Minds and Machines since Inductive reasoning. Deductive reasoning

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1 PSY 3360 / CGS 3325 Historical Perspectives on Psychology Minds and Machines since 1600 Dr. Peter Assmann Summer 2017 Some key concepts Rationalism vs. empiricism Induction and deduction Free will vs. determinism Dualism vs. monism Mind-body problem Nativism Deductive reasoning All men are mortal. (major premise) Socrates is a man. (minor premise) Socrates is mortal. (conclusion) Inductive reasoning 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 Francis Bacon ( ) Thomas Hobbes ( ) John Locke ( ) George Berkeley ( ) David Hume ( ) David Hume ( ) Radical skepticism style of inquiry psychological feeling response to Descartes Epistemology Statements of fact Relations of ideas Causality 1

2 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 ( ) 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

3 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. 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. Key concepts Kant regarded mathematics as a priori and synthetic because it depends on the pure intuitions of the elements of time and space. 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, a priori a posteriori "Triangles were the earliest figures to be discovered in geometry." The truth of such a statement cannot be known by an analysis of the subject. analytic synthetic Triangles have three sides Kant s categories; mathematics (none) Some birds fly south in winter 3

4 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. 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). Critique of Pure Reason Space and time existonlyaspartof 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 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. Kant's categories There are four main categories with 3 subcategories each, for a total of 12: quantity quality relation modality unity, plurality, totality reality, negation, limitation substance & accident, cause & effect, reciprocity possibility, existence, necessity 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

5 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. 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 theory of causality Hume's rejection of causality Kant s answer: Causality is Co-occurrence of events fundamental to science and human knowledge Habitual association (Illusory) feeling of necessity a relationship not based on observation (synthetic a posteriori) or logic (analytic a priori) imposed by the structure of the human mind (synthetic a priori) Kant s psychological theory Kant s contributions to psychology Noumena and phenomena Space, time and the 12 categories of experience Perception is an active process The mind actively participates in the construction of reality 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. 5

6 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. 19 th 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. Emerging viewpoints 19 th century developments 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. 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 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)? 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

7 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? Early theories Aristotle ( BC) Believed the heart, not the brain, was the organ of thought Galen ( AD) Recognized the brain s role in sensation and motor control; animal spirits Aristotle ( BC) Renaissance period René Descartes ( ) 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 René Descartes ( ) 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 ( ) John Locke s teacher detailed brain anatomy gray matter & white matter Cerebral cortex has convolutions; blood vessels Anatomy of subcortical centers Thomas Willis 7

8 Franz Gall ( ) 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. Physiognomy and 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 ( ) 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 ( ) 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. 19 th century developments Luigi Galvani ( ) 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

9 19 th century developments Johannes Purkinje ( ) 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, th century developments Gustav Fritsch ( ) Eduard 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 ( ) cranial damage and lesions as a means of studying localization of cerebral function in humans. 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. Pierre Paul Broca ( ) Broca s area: frontal lobe of the left hemisphere Hemispheric lateralization of function language center? Carl Wernicke ( ) Aphasia disorders of language 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. Pierre Paul Broca ( ) 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 Carl Wernicke ( ) 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

10 19 th Century Neuroscience Vitalism vs. Mechanism 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 Vitalism: living things share a vital force that cannot be explained by the physical sciences (Müller) Mechanism: same laws apply to living and non-living things (Helmholtz) Johannes Müller Johannes Müller ( ) 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 ( ) Hermann Ludwig Ferdinand von Helmholtz ( ) 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) "Willed behavior is instantaneous." Mechanism: same laws apply to living and non-living things (Helmholtz) Principle of conservation of energy Johannes Müller

11 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 Speed of nerve conduction Reaction times in humans: subjects pressed a button in response to tactile stimulus Response times ~ feet per second Nerve transmission rate is finite (relatively slow) Hermann Ludwig Ferdinand von Helmholtz ( ) 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). Helmholtz' theory of perception Perception = active, unconscious, automatic, logical processes Unconscious inference Role of learning and memory in transforming sensory information Experiments with distorted lenses Motion pictures succession of still images Railroad tracks are parallel but seem to converge in the distance Young-Helmholtz theory of color vision Munsell color system 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 Hue: dominant wavelength Value: brightness Chroma: purity 11

12 Auditory theory Helmholtz proposed that the cochlea, part of the inner ear, is responsible for frequency analysis in hearing. Theory of 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 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 Frequency analysis Fourier analysis: mathematical decomposition of any complex waveform into simple sinusoidal components Joseph Fourier ( ) Complex wave Simple sine waves Frequency analysis Fourier synthesis: any complex waveform can be reconstructed (synthesized) from sine waves. Response to a low-frequency sound Simple sine waves Joseph Fourier ( ) Vowel sound 12

13 Response to a high-frequency sound Frequency and pitch Physical property: Frequency Psychological property: Pitch Sine wave Complex 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 Physical property: Frequency Psychological property: Pitch Sine wave Complex 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 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

14 Pitch Perception Pitch Perception Helmholtz proposed that the location (place) of maximum vibration along the basilar membrane determines the pitch we perceive. Intensity Sine wave Complex sounds have many components; the activation produced by the lowest one (called the fundamental frequency) determines the pitch. Intensity Complex wave Frequency Frequency Frequency analysis Problem of the missing fundamental Sine wave Complex wave Original Frequency (in cycles/sec, or Hz) Missing fundamental Intensity Frequency Intensity Frequency 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 Helmholtz studies of nerve conduction Nerve propogation time in humans Problem: how to separate nerve propogation speed from other factors? 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 Invented by Hipp in the 1860s Simple reaction time in humans: subjects pressed a button in response to tactile stimulus Compared reaction times at different body locations By subtracting one reaction time from another, he estimated that nerve impulses travel at ~ feet per second Nerve impulses travel about 2x as fast in humans as in frogs Mental processes take time; they can be measured. 14

15 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). Franciscus Cornelius Donders ( ) Dutch physiologist 15 years after Helmholtz study, Donders measured simple reaction time to visual stimuli Franciscus Cornelius Donders Next Donders presented a series of stimuli and asked subjects to respond to only one, specified beforehand. The extra time provided a measure of the mental act of discrimination. Franciscus Cornelius Donders Subtractive method: the time taken to discriminate the complex stimulus minus the time to discriminate the simple stimulus. A B C D E A B C D E Response Response Franciscus Cornelius Donders Choice reaction time: several different stimuli are presented and the response to each one is different. Franciscus Cornelius Donders The time required to make a choice is determined by subtracting both simple and discrimination reaction times from the choice reaction time. Stimulus: A B C D E Stimulus: A B C D E Response: a b c d e Response: a b c d e "mental chronometry" 15

16 19 th century developments Johannes Purkinje ( ) 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, th century developments Luigi Galvani ( ) 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 19 th century developments Fritsch Gustav Fritsch ( ) Eduard Hitzig ( ) 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 ( ) cranial damage and lesions as a means of studying localization of cerebral function in humans. 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. Pierre Paul Broca ( ) Broca s area: frontal lobe of the left hemisphere Hemispheric lateralization of function language center? 16

17 Carl Wernicke ( ) Aphasia disorders of language 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. Pierre Paul Broca ( ) 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 Carl Wernicke ( ) 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 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. Emil du Bois-Reymond ( ) 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. 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 ( ) 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

18 Karl Lashley engram 1. Mass Action 2. Equipotentiality Wilder Penfield ( ) 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