Kant's Objections to Psychology The mind wasn't a physical entity The mind could not be objectively observed since it was always changing and introspection would always reveal the mind in the process of introspecting itself The mind could not be subjected to mathematical descriptions and formulations

Kant's Objections to Psychology The mind wasn't a physical entity The mind could not be objectively observed since it was always changing and introspection would always reveal the mind in the process of introspecting itself The mind could not be subjected to mathematical descriptions and formulations

Kant's Objections to Psychology The mind wasn't a physical entity BUT Helmholtz measured the speed of the nerve impulse and other aspects of the physical basis of thought The mind could not be objectively observed since it was always changing and introspection would always reveal the mind in the process of introspecting itself BUT Donders invented the reaction time methodology which provided objective measures of the functioning of other minds The mind could not be subjected to mathematical descriptions and formulations BUT Weber and Fechner came up with precise mathematical expressions that related the intensity of a physical stimulus (like light) to the magnitude of the subjective sensory impression it produced (perceived brightness)

Some Precursors to Psychology Johannes Müller c.1826 Doctrine of Specific Nerve Energies Hermann von Helmholtz c.1850 rate of nerve conduction: 50 m/sec perception as "unconscious inference" theories of color vision, hearing Ernst Weber c.1840 perceptual judgements are relative, not absolute Gustav Fechner c.1860 "psychophysics": absolute difference in psychological experience is proportional difference in physical stimulus Franciscus Donders c.1865 subtractive logic in reaction time studies

Doctrine of Specific Nerve Energies (Johannes Müller, 1826) quality of sensation (visual, auditory, touch, etc.) depends on which nerve fibers are stimulated - NOT on the stimulus itself fibers of optic nerve are normally stimulated by light - may also be stimulated by pressure, electric current, and so on - any stimulation will yield experience of light any sensory experience must have corresponding set of nerve fibers: experiences of brightness, color, loudness, pitch, etc.

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Fig. 5.28

Some Precursors to Psychology Johannes Müller c.1826 Doctrine of Specific Nerve Energies Hermann von Helmholtz c.1850 rate of nerve conduction: 50 m/sec perception as "unconscious inference" theories of color vision, hearing Ernst Weber c.1840 perceptual judgements are relative, not absolute Gustav Fechner c.1860 "psychophysics": absolute difference in psychological experience is proportional difference in physical stimulus Franciscus Donders c.1865 subtractive logic in reaction time studies

HELMHOLTZIAN PROGRAM monocular depth cues (only one eye needed): - linear perspective - convergence point is far away - interposition - nearer objects will occlude (block) farther objects - relative size - nearer objects cast larger retinal images than farther objects (of same size) "unconscious inference" - best guess at what DISTAL stimulus PROBABLY caused the PROXIMAL stimulus (the retinal image) - perception is always in the direction of the best inference ("maximum likelihood")

infer distance of object: - learned: points nearer to where lines converge are farther away - retinal image: object appears near to where lines converge (linear convergence cue) - infer: DISTAL object must be far away use this inference to get SIZE information: - learned: far off objects produce smaller retinal images - retinal image: two objects appear to have SAME retinal image size (relative size cue) - infer: the farther-away DISTAL object must be LARGER

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Some Precursors to Psychology Johannes Müller c.1826 Doctrine of Specific Nerve Energies Hermann von Helmholtz c.1850 rate of nerve conduction: 50 m/sec perception as "unconscious inference" theories of color vision, hearing Ernst Weber c.1840 perceptual judgements are relative, not absolute Gustav Fechner c.1860 "psychophysics": absolute difference in psychological experience is proportional difference in physical stimulus Franciscus Donders c.1865 subtractive logic in reaction time studies

PSYCHOPHYSICS: relation of physical variables of environment to sensations in our experience How is intensity of light related to our experience of "brightness"? to be detected, intensity must exceed the absolute threshold - for a change to be detected, intensity must increase by the difference threshold

"just noticeable difference" (j.n.d.): light of intensity I increased by∆I notice? 300 1 NO 300 2 NO 300 3 NO 300 4 NO 300 5 YES!

Weber's Law (1834): ∆I / I is constant ∆I / I = change in intensity relative to original intensity - for I = 60, ∆I = 1 - for I = 120, ∆I = 2 - for I = 180, ∆I = 3 so for vision, ∆I / I = 1/60: "Weber fraction" - smaller Weber fraction means greater sensitivity - hearing is less sensitive: ∆I / I = 1/10

Table 5.1

Fechner’s Law (1860): coined the term “Weber’s Law” for ∆R / R = k the ratio of change in stimulus intensity to original stimulus intensity is a constant R is “Reiz”, German for “stimulus”; ∆R is the “just noticeable difference” or “jnd”; the constant “k” is specific to a sense modality, e.g., vision, hearing, comparing lifted weights then “Fechner’s Law” said more generally S = k * log R “S” is the intensity of the sensation experienced, “log R” is the logarithm of the stimulus intensity, “k” is the constant relating them for a given sense modality (vision, audition, etc.) logarithms are exponents, so the sensation becomes arithmetically or linearly stronger as the stimulus intensity gets exponentially stronger still recognized today, though modified for extreme values by S.S. Stevens in 1957

Some Precursors to Psychology Johannes Müller c.1826 Doctrine of Specific Nerve Energies Hermann von Helmholtz c.1850 rate of nerve conduction: 50 m/sec perception as "unconscious inference" theories of color vision, hearing Ernst Weber c.1840 perceptual judgements are relative, not absolute Gustav Fechner c.1860 "psychophysics": absolute difference in psychological experience is proportional difference in physical stimulus Franciscus Donders c.1865 subtractive logic in reaction time studies

Donders’s reaction time method and subtractive logic (1869): SIMPLE reaction time: respond to stimulus (such as a light) with a predetermined response (such as pressing a button) DISCRIMINATION reaction time: respond to only one of several different stimuli A B C D E (e.g., only to stimulus C) - discrimination time = discrimination reaction time minus simple reaction time CHOICE reaction time: make different response so each of several different stimuli (e.g., reponse “a” to simulus A, “b” to B, etc.) choice time = choice reaction time minus both simple and discrimination reaction times measured time course of mental operations but proved too variable, requiring 20th century statistics for data analysis re-emerged in 1960s in cognitive psychology, as indirect measure of the processing demands implied by different models of cognition

Early Psychology Wilhelm Wundt c. 1879; d. 1920 (Leipzig) voluntarism: emphasizes volition, attention, will, choice, purpose; more Locke than Hume use reaction time, "experimental" introspection, etc. to replicate and extend earlier findings first "paradigm" in psychology (in both senses) only lower level processes studied in lab; higher processes studied through "Volkerpsychologie" examine religion, customs, history, language, morals, art, law, etc. to reveal higher thought processes elements of thought organized by LAWS, but not empiricist laws of association

Early Psychology Edward Titchener c. 1899; d. 1927 (Cornell) "structuralism": emphasizes static elements of consciousness - structure, not function study consciousness (mental experience at a moment); mind was the lifetime accumulation of experience used introspectors trained to avoid the "stimulus error" catalog sensations and their laws of combination -- mainly association by contiguity eventually "discovered" 40,000 sensations (30,000 visual, 12,000 auditory, 20 other) all thought was image-based ignored: applications, animals, abnormality, personality, development, individual differences, evolution

Early Psychology Oswald Kulpe c. 1894; d. 1915 (Wurzburg) Imageless thoughts arose in context of judgements about "heavier than" or "lighter than" ex.: no images accompanied thoughts of search, doubt, confidence, hesitation Titchener et al debated this issue, 1907-1915: arguments about who was doing introspection better, more accurately, more reliably till finally… John Watson (1913) "Psychology as the Behaviorist Views It"

John Broadus Watson (1913): Psychology as the Behaviorist Views it John Broadus Watson (1913): Psychology as the Behaviorist Views it. Psychological Review, 20, 158-177; first paragraph: "Psychology as the behaviorist views it is a purely objective experimental branch of natural science. Its theoretical goal is the prediction and control of behavior. Introspection forms no essential part of its methods, nor is the scientific value of its data dependent upon the readiness with which they lend themselves to interpretation in terms of consciousness. The behaviorist, in his efforts to get a unitary scheme of animal response, recognizes no dividing line between man and brute. The behavior of man, with all of its refinement and complexity, forms only a part of the behaviorist's total scheme of investigation.” rats running in mazes objectively make a certain number of wrong turns and objectively take longer or shorter times use of conditioning (not yet differentiated into classical and operant)

Early Psychology Functionalism influenced by William James and Darwinian evolutionary theory, which assumed mind had a function useful to an animal's survival opposed to structuralism: instead of understanding elements and structure of mind through introspection, study how mind and behavior better adapt an organism to its environment interested in both mind and behavior -- so methods included introspection, but also puzzle boxes, mazes, mental tests, etc. studied animal behavior as well as special human populations (children, mentally ill) interested in practical applications (in self-improvement, education, industry, etc.) as well as theorizing interested in motivation of behavior, whereas structuralism didn't depend on motivation interested in individual differences (e.g., in intelligence, motivation, etc.), instead of solely focusing on universal characteristics of mind