Richard J. Herrnstein was Edgar Pierce Professor of Psychology at Harvard University. Edwin G. Boring was Edgar Pierce Professor of Psychology, Emeritus, at Harvard University.

More than a quarter of the articles are translated into English for the first time. A fine, well-balanced contribution to the history of psychology.

• PART I: SENSORY SPECIFICATION * Aristotle on the Five Senses, ca. 350 BCE * Isaac Newton on the Seven Colors of the Spectrum, 1675 * Isaac Newton on the Color Circle, 1704 * Thomas Young on Newton and the Excitation of the Retina by Colors, 1802 * John Locke on Primary and Secondary Qualities, 1690 * Charles Bell on Spinal Nerve Roots, 1811 * Francois Magendie on Spinal Nerve Roots, 1822 * Charles Bell on the Specificity of Sensory Nerves, 1811 * Johannes Muffler on the Specific Energies of Nerves, 1838 * Ernst Heinrich Weber on the Sense of Touch and Common Sensibility, 1846 * Hermann Ludwig Ferdinand von Helmholtz on the Three-Color Theory of Vision and Visual Specific Nerve Energies, 1860 * Hermann Ludwig Ferdinand von Helmholtz on the Resonance Theory of Hearing and Auditory Specific Nerve Energies, 1863 * Max von Frey on the Four Cutaneous Senses, 1904 * Edward Bradford Titchener on the Number of Sensory Elements, 1896 PART II: PSYCHOPHYSICS AND SENSORY MEASUREMENT * Pierre Bouguer on the Differential Threshold for Illumination, 1760 * Charles Eduard Joseph Delezenne on the Differential Threshold for the Pitch of Tones, 1827 * Ernst Heinrich Weber on Weber's Law, 1834 * Gustav Theodor Fechner on Fechner's Law, 1860 * Joseph Antoine Ferdinand Plateau on the Measurement of Sensation, 1872 * Joseph Remi Leopold Delboeuf on Sensed Contrast as the Measure of Sensation, 1883 * Edward Bradford Titchener on the Sense Distance as the Measure of Sensation, 1905 PART III: THE RETINAL IMAGE AND THE ORIENTATION OF PERCEIVED OBJECTS * Epicurus on Perception of Objects as Mediated by the Images that Emanate from the Objects, ca. 300 BCE * Johannes Kepler on the Crystalline Humor as a Lens and the Inversion of the Retinal Image, 1604 * William Molyneux on the Inverted Retinal Image, 1692 * Johannes Miller on Subjective Visual Size and Position in Relation to the Retinal Image, 1826 * George Malcolm Stratton on Visual Localization and the Inversion of the Retinal Image, 1897 PART IV: THE VISUAL PERCEPTION OF SIZE AND DISTANCE * Rene Descartes on the Visual Perception of Size, Shape, and Distance, 1638 * George Berkeley on the Visual Perception of Distance and Magnitude, 1709 * Charles Wheatstone on Binocular Parallax and the Stereoscopic Perception of Depth, 1838 PART V: NATIVISTIC AND EMPIRISTIC THEORIES OF SPACE PERCEPTION * Immanuel Kant on the A Priori Nature of Space, 1781 * Rudolf Hermann Lotze on Local Signs in Their Relation to the Perception of Space, 1852 * Ernst Heinrich Weber on Sensory Circles and Cutaneous Space Perception, 1852 * Ewald Hering on the Nativistic Theory of Visual Space Perception, 1864 * Hermann Ludwig Ferdinand von Helmholtz on Empiricism in Perception, 1866 * Max Wertheimer on the Phi Phenomenon as an Example of Nativism in Perception, 1912 PART VI: OBJECTIVE REFERENCE * George Berkeley on the Role of Association in the Objective Reference of Perception, 1709 * Thomas Reid on the Distinction between Sensation and Perception, 1785 * Thomas Brown on Sensation, Perception, and the Associative Explanation of Objective Reference, 1820 * John Stuart Mill on the Permanent Possibilities of Sensation, 1865 * Hermann Ludwig Ferdinand von Helmholtz on Perception and the Unconscious Conclusion, 1866 * Edward Bradford Titchener on the Context Theory of Meaning, 1910 * Edwin Bissell Holt on Response as the Essence of Cognition, 1915 * Max Wertheimer on Objects as Immediately Given to Consciousness, 1923 PART VII: CEREBRAL LOCALIZATION * Rene Descartes on the Interaction of Mind and Brain, 1650 * Franz Joseph Gall on Phrenology, the Localization of the Functions of the Brain, 1825 * Pierre Jean Marie Flourens on the Functions of the Brain, 1824 * Paul Broca on the Speech Center, 1861 * Gustav Fritsch and Eduard Hitzig on Cerebral Motor Centers, 1870 * John Hughlings Jackson on Dissolution of the Nervous System, 1884 * Shepherd Ivory Franz on the Variability of the Motor Centers, 1915 * Karl Spencer Lash!ey on Cerebral Equipotentiality and Mass Action, 1929 * Henry Head on Vigilance, 1926 PART VIII: PSYCHOPHYSIOLOGICAL ISOMORPHISM * Ewald Hering: Anticipation of Psychophysiolgical Isomorphism, 1878 * Georg Elias Muller on the Psychophysical Axioms, 1896 * Max Wertheimer on the Isomorphic Relation between Seen Movement and Cortical Short Circuit, 1912 * Wolfgang Kohler on Isomorphism, 1920 PART IX: THE REFLEX * Rene Descartes on Mechanism in Human Action, 1662 * Julien Offray de la Mettrie on the Extension of Mechanism to the Human Soul, 1748 * David Hart!ey on Voluntary and Involuntary Action, 1749 * Robert Whytt on Empirical Reflexology, 1751 * George Prochaska on the Nervous System, 1784 * Marshall Hall on the Spinal Nervous System, 1843, 1850 * Ivan Miehailovieh Seehenov on Reflexology and Psychology, 1863 * John Dewey against Reflexology, 1896 PART X: ASSOCIATION * Aristotle on the Associative Nature of Memory, ca. 350 BCE * Thomas Hobbes on the Train of Thought, 1651 * John Locke on Disorders of the Mind, 1700 * George Berkeley on Arbitrary Connections among Ideas, 1733 * David Hume on a Psychological Analogue of Gravitation, 1739 * David Hartley on Association: Successive and Simultaneous, Simple and Complex, 1749 * Thomas Brown on the Secondary Laws of Association, 1820 * James Mill on Mental Mechanics, 1829 * John Stuart Mill on Mental Chemistry, 1843 * Herbert Spencer on Intelligence, 1855 * William James on the Limitations of Associationism, 1890 * Wilhelm Wundt on Psychological Analysis and Creative Synthesis, 1896 PART XI: EVOLUTION AND INDIVIDUAL DIFFERENCES * Charles Robert Darwin on the Theory of Evolution, 1859 * Francis Galton on the Inheritance of Intelligence, 1869 * Francis Galton on Mental Capacity, 1883 * James McKeen Cattell on Mental Tests, 1890 * Alfred Binet and Victor Henri on the Psychology of Individual Differences, 1895 * Hermann Ebbinghaus on the Completion Test, 1897 * Stella Emily Sharp on a Test of Mental Testing, 1899 * Clark Wissler on the Inadequacy of Mental Tests, 1901 * Charles Edward Spearman on General Intelligence, 1904 * William Stern on the Mental Quotient, 1912 PART XII: COMPARATIVE PSYCHOLOGY * George John Romanes on Comparative Psychology, 1882 * Conwy Lloyd Morgan on Lloyd Morgan's Canon, 1894 * Jacques Loeb on Associative Memory, 1899 * Herbert Spencer Jennings on the Continuity of Psychological Processes, 1906 PART XIII: FUNCTIONALISM * William James on the Function of Consciousness, 1890 * James Mark Baldwin on the Psychology of Children, 1895 * James Rowland Angell on Functionalism, 1906 * John Broadus Watson on Behaviorism, 1913 PART XIV: LEARNING * Hermann Ebbinghaus on the Learning of Nonsense Syllables, 1995 * Mary Whiton Calkins on the Learning of Paired Associates, 1896 * Edward Lee Thorndike on Animal Learning, 1898 * Robert Mearns Yerkes on the Intelligence of the Turtle, 1901 * Willard Stanton Small on the Maze, 1901 * Edward Lee Thorndike and Robert Sessions Woodworth on Transfer of Training, 1901 * Ivan Petrovich Pavlov on Conditioned Reflexes, 1904 * Wolfgang Kohler on the Insight of Apes, 1917 PART XV:

Richard J. Herrnstein was Edgar Pierce Professor of Psychology at Harvard University. Edwin G. Boring was Edgar Pierce Professor of Psychology, Emeritus, at Harvard University.

More than a quarter of the articles are translated into English for the first time. A fine, well-balanced contribution to the history of psychology.

• PART I: SENSORY SPECIFICATION * Aristotle on the Five Senses, ca. 350 BCE * Isaac Newton on the Seven Colors of the Spectrum, 1675 * Isaac Newton on the Color Circle, 1704 * Thomas Young on Newton and the Excitation of the Retina by Colors, 1802 * John Locke on Primary and Secondary Qualities, 1690 * Charles Bell on Spinal Nerve Roots, 1811 * Francois Magendie on Spinal Nerve Roots, 1822 * Charles Bell on the Specificity of Sensory Nerves, 1811 * Johannes Muffler on the Specific Energies of Nerves, 1838 * Ernst Heinrich Weber on the Sense of Touch and Common Sensibility, 1846 * Hermann Ludwig Ferdinand von Helmholtz on the Three-Color Theory of Vision and Visual Specific Nerve Energies, 1860 * Hermann Ludwig Ferdinand von Helmholtz on the Resonance Theory of Hearing and Auditory Specific Nerve Energies, 1863 * Max von Frey on the Four Cutaneous Senses, 1904 * Edward Bradford Titchener on the Number of Sensory Elements, 1896 PART II: PSYCHOPHYSICS AND SENSORY MEASUREMENT * Pierre Bouguer on the Differential Threshold for Illumination, 1760 * Charles Eduard Joseph Delezenne on the Differential Threshold for the Pitch of Tones, 1827 * Ernst Heinrich Weber on Weber's Law, 1834 * Gustav Theodor Fechner on Fechner's Law, 1860 * Joseph Antoine Ferdinand Plateau on the Measurement of Sensation, 1872 * Joseph Remi Leopold Delboeuf on Sensed Contrast as the Measure of Sensation, 1883 * Edward Bradford Titchener on the Sense Distance as the Measure of Sensation, 1905 PART III: THE RETINAL IMAGE AND THE ORIENTATION OF PERCEIVED OBJECTS * Epicurus on Perception of Objects as Mediated by the Images that Emanate from the Objects, ca. 300 BCE * Johannes Kepler on the Crystalline Humor as a Lens and the Inversion of the Retinal Image, 1604 * William Molyneux on the Inverted Retinal Image, 1692 * Johannes Miller on Subjective Visual Size and Position in Relation to the Retinal Image, 1826 * George Malcolm Stratton on Visual Localization and the Inversion of the Retinal Image, 1897 PART IV: THE VISUAL PERCEPTION OF SIZE AND DISTANCE * Rene Descartes on the Visual Perception of Size, Shape, and Distance, 1638 * George Berkeley on the Visual Perception of Distance and Magnitude, 1709 * Charles Wheatstone on Binocular Parallax and the Stereoscopic Perception of Depth, 1838 PART V: NATIVISTIC AND EMPIRISTIC THEORIES OF SPACE PERCEPTION * Immanuel Kant on the A Priori Nature of Space, 1781 * Rudolf Hermann Lotze on Local Signs in Their Relation to the Perception of Space, 1852 * Ernst Heinrich Weber on Sensory Circles and Cutaneous Space Perception, 1852 * Ewald Hering on the Nativistic Theory of Visual Space Perception, 1864 * Hermann Ludwig Ferdinand von Helmholtz on Empiricism in Perception, 1866 * Max Wertheimer on the Phi Phenomenon as an Example of Nativism in Perception, 1912 PART VI: OBJECTIVE REFERENCE * George Berkeley on the Role of Association in the Objective Reference of Perception, 1709 * Thomas Reid on the Distinction between Sensation and Perception, 1785 * Thomas Brown on Sensation, Perception, and the Associative Explanation of Objective Reference, 1820 * John Stuart Mill on the Permanent Possibilities of Sensation, 1865 * Hermann Ludwig Ferdinand von Helmholtz on Perception and the Unconscious Conclusion, 1866 * Edward Bradford Titchener on the Context Theory of Meaning, 1910 * Edwin Bissell Holt on Response as the Essence of Cognition, 1915 * Max Wertheimer on Objects as Immediately Given to Consciousness, 1923 PART VII: CEREBRAL LOCALIZATION * Rene Descartes on the Interaction of Mind and Brain, 1650 * Franz Joseph Gall on Phrenology, the Localization of the Functions of the Brain, 1825 * Pierre Jean Marie Flourens on the Functions of the Brain, 1824 * Paul Broca on the Speech Center, 1861 * Gustav Fritsch and Eduard Hitzig on Cerebral Motor Centers, 1870 * John Hughlings Jackson on Dissolution of the Nervous System, 1884 * Shepherd Ivory Franz on the Variability of the Motor Centers, 1915 * Karl Spencer Lash!ey on Cerebral Equipotentiality and Mass Action, 1929 * Henry Head on Vigilance, 1926 PART VIII: PSYCHOPHYSIOLOGICAL ISOMORPHISM * Ewald Hering: Anticipation of Psychophysiolgical Isomorphism, 1878 * Georg Elias Muller on the Psychophysical Axioms, 1896 * Max Wertheimer on the Isomorphic Relation between Seen Movement and Cortical Short Circuit, 1912 * Wolfgang Kohler on Isomorphism, 1920 PART IX: THE REFLEX * Rene Descartes on Mechanism in Human Action, 1662 * Julien Offray de la Mettrie on the Extension of Mechanism to the Human Soul, 1748 * David Hart!ey on Voluntary and Involuntary Action, 1749 * Robert Whytt on Empirical Reflexology, 1751 * George Prochaska on the Nervous System, 1784 * Marshall Hall on the Spinal Nervous System, 1843, 1850 * Ivan Miehailovieh Seehenov on Reflexology and Psychology, 1863 * John Dewey against Reflexology, 1896 PART X: ASSOCIATION * Aristotle on the Associative Nature of Memory, ca. 350 BCE * Thomas Hobbes on the Train of Thought, 1651 * John Locke on Disorders of the Mind, 1700 * George Berkeley on Arbitrary Connections among Ideas, 1733 * David Hume on a Psychological Analogue of Gravitation, 1739 * David Hartley on Association: Successive and Simultaneous, Simple and Complex, 1749 * Thomas Brown on the Secondary Laws of Association, 1820 * James Mill on Mental Mechanics, 1829 * John Stuart Mill on Mental Chemistry, 1843 * Herbert Spencer on Intelligence, 1855 * William James on the Limitations of Associationism, 1890 * Wilhelm Wundt on Psychological Analysis and Creative Synthesis, 1896 PART XI: EVOLUTION AND INDIVIDUAL DIFFERENCES * Charles Robert Darwin on the Theory of Evolution, 1859 * Francis Galton on the Inheritance of Intelligence, 1869 * Francis Galton on Mental Capacity, 1883 * James McKeen Cattell on Mental Tests, 1890 * Alfred Binet and Victor Henri on the Psychology of Individual Differences, 1895 * Hermann Ebbinghaus on the Completion Test, 1897 * Stella Emily Sharp on a Test of Mental Testing, 1899 * Clark Wissler on the Inadequacy of Mental Tests, 1901 * Charles Edward Spearman on General Intelligence, 1904 * William Stern on the Mental Quotient, 1912 PART XII: COMPARATIVE PSYCHOLOGY * George John Romanes on Comparative Psychology, 1882 * Conwy Lloyd Morgan on Lloyd Morgan's Canon, 1894 * Jacques Loeb on Associative Memory, 1899 * Herbert Spencer Jennings on the Continuity of Psychological Processes, 1906 PART XIII: FUNCTIONALISM * William James on the Function of Consciousness, 1890 * James Mark Baldwin on the Psychology of Children, 1895 * James Rowland Angell on Functionalism, 1906 * John Broadus Watson on Behaviorism, 1913 PART XIV: LEARNING * Hermann Ebbinghaus on the Learning of Nonsense Syllables, 1995 * Mary Whiton Calkins on the Learning of Paired Associates, 1896 * Edward Lee Thorndike on Animal Learning, 1898 * Robert Mearns Yerkes on the Intelligence of the Turtle, 1901 * Willard Stanton Small on the Maze, 1901 * Edward Lee Thorndike and Robert Sessions Woodworth on Transfer of Training, 1901 * Ivan Petrovich Pavlov on Conditioned Reflexes, 1904 * Wolfgang Kohler on the Insight of Apes, 1917 PART XV:

Richard J. Herrnstein was Edgar Pierce Professor of Psychology at Harvard University. Edwin G. Boring was Edgar Pierce Professor of Psychology, Emeritus, at Harvard University.

More than a quarter of the articles are translated into English for the first time. A fine, well-balanced contribution to the history of psychology.

• PART I: SENSORY SPECIFICATION * Aristotle on the Five Senses, ca. 350 BCE * Isaac Newton on the Seven Colors of the Spectrum, 1675 * Isaac Newton on the Color Circle, 1704 * Thomas Young on Newton and the Excitation of the Retina by Colors, 1802 * John Locke on Primary and Secondary Qualities, 1690 * Charles Bell on Spinal Nerve Roots, 1811 * Francois Magendie on Spinal Nerve Roots, 1822 * Charles Bell on the Specificity of Sensory Nerves, 1811 * Johannes Muffler on the Specific Energies of Nerves, 1838 * Ernst Heinrich Weber on the Sense of Touch and Common Sensibility, 1846 * Hermann Ludwig Ferdinand von Helmholtz on the Three-Color Theory of Vision and Visual Specific Nerve Energies, 1860 * Hermann Ludwig Ferdinand von Helmholtz on the Resonance Theory of Hearing and Auditory Specific Nerve Energies, 1863 * Max von Frey on the Four Cutaneous Senses, 1904 * Edward Bradford Titchener on the Number of Sensory Elements, 1896 PART II: PSYCHOPHYSICS AND SENSORY MEASUREMENT * Pierre Bouguer on the Differential Threshold for Illumination, 1760 * Charles Eduard Joseph Delezenne on the Differential Threshold for the Pitch of Tones, 1827 * Ernst Heinrich Weber on Weber's Law, 1834 * Gustav Theodor Fechner on Fechner's Law, 1860 * Joseph Antoine Ferdinand Plateau on the Measurement of Sensation, 1872 * Joseph Remi Leopold Delboeuf on Sensed Contrast as the Measure of Sensation, 1883 * Edward Bradford Titchener on the Sense Distance as the Measure of Sensation, 1905 PART III: THE RETINAL IMAGE AND THE ORIENTATION OF PERCEIVED OBJECTS * Epicurus on Perception of Objects as Mediated by the Images that Emanate from the Objects, ca. 300 BCE * Johannes Kepler on the Crystalline Humor as a Lens and the Inversion of the Retinal Image, 1604 * William Molyneux on the Inverted Retinal Image, 1692 * Johannes Miller on Subjective Visual Size and Position in Relation to the Retinal Image, 1826 * George Malcolm Stratton on Visual Localization and the Inversion of the Retinal Image, 1897 PART IV: THE VISUAL PERCEPTION OF SIZE AND DISTANCE * Rene Descartes on the Visual Perception of Size, Shape, and Distance, 1638 * George Berkeley on the Visual Perception of Distance and Magnitude, 1709 * Charles Wheatstone on Binocular Parallax and the Stereoscopic Perception of Depth, 1838 PART V: NATIVISTIC AND EMPIRISTIC THEORIES OF SPACE PERCEPTION * Immanuel Kant on the A Priori Nature of Space, 1781 * Rudolf Hermann Lotze on Local Signs in Their Relation to the Perception of Space, 1852 * Ernst Heinrich Weber on Sensory Circles and Cutaneous Space Perception, 1852 * Ewald Hering on the Nativistic Theory of Visual Space Perception, 1864 * Hermann Ludwig Ferdinand von Helmholtz on Empiricism in Perception, 1866 * Max Wertheimer on the Phi Phenomenon as an Example of Nativism in Perception, 1912 PART VI: OBJECTIVE REFERENCE * George Berkeley on the Role of Association in the Objective Reference of Perception, 1709 * Thomas Reid on the Distinction between Sensation and Perception, 1785 * Thomas Brown on Sensation, Perception, and the Associative Explanation of Objective Reference, 1820 * John Stuart Mill on the Permanent Possibilities of Sensation, 1865 * Hermann Ludwig Ferdinand von Helmholtz on Perception and the Unconscious Conclusion, 1866 * Edward Bradford Titchener on the Context Theory of Meaning, 1910 * Edwin Bissell Holt on Response as the Essence of Cognition, 1915 * Max Wertheimer on Objects as Immediately Given to Consciousness, 1923 PART VII: CEREBRAL LOCALIZATION * Rene Descartes on the Interaction of Mind and Brain, 1650 * Franz Joseph Gall on Phrenology, the Localization of the Functions of the Brain, 1825 * Pierre Jean Marie Flourens on the Functions of the Brain, 1824 * Paul Broca on the Speech Center, 1861 * Gustav Fritsch and Eduard Hitzig on Cerebral Motor Centers, 1870 * John Hughlings Jackson on Dissolution of the Nervous System, 1884 * Shepherd Ivory Franz on the Variability of the Motor Centers, 1915 * Karl Spencer Lash!ey on Cerebral Equipotentiality and Mass Action, 1929 * Henry Head on Vigilance, 1926 PART VIII: PSYCHOPHYSIOLOGICAL ISOMORPHISM * Ewald Hering: Anticipation of Psychophysiolgical Isomorphism, 1878 * Georg Elias Muller on the Psychophysical Axioms, 1896 * Max Wertheimer on the Isomorphic Relation between Seen Movement and Cortical Short Circuit, 1912 * Wolfgang Kohler on Isomorphism, 1920 PART IX: THE REFLEX * Rene Descartes on Mechanism in Human Action, 1662 * Julien Offray de la Mettrie on the Extension of Mechanism to the Human Soul, 1748 * David Hart!ey on Voluntary and Involuntary Action, 1749 * Robert Whytt on Empirical Reflexology, 1751 * George Prochaska on the Nervous System, 1784 * Marshall Hall on the Spinal Nervous System, 1843, 1850 * Ivan Miehailovieh Seehenov on Reflexology and Psychology, 1863 * John Dewey against Reflexology, 1896 PART X: ASSOCIATION * Aristotle on the Associative Nature of Memory, ca. 350 BCE * Thomas Hobbes on the Train of Thought, 1651 * John Locke on Disorders of the Mind, 1700 * George Berkeley on Arbitrary Connections among Ideas, 1733 * David Hume on a Psychological Analogue of Gravitation, 1739 * David Hartley on Association: Successive and Simultaneous, Simple and Complex, 1749 * Thomas Brown on the Secondary Laws of Association, 1820 * James Mill on Mental Mechanics, 1829 * John Stuart Mill on Mental Chemistry, 1843 * Herbert Spencer on Intelligence, 1855 * William James on the Limitations of Associationism, 1890 * Wilhelm Wundt on Psychological Analysis and Creative Synthesis, 1896 PART XI: EVOLUTION AND INDIVIDUAL DIFFERENCES * Charles Robert Darwin on the Theory of Evolution, 1859 * Francis Galton on the Inheritance of Intelligence, 1869 * Francis Galton on Mental Capacity, 1883 * James McKeen Cattell on Mental Tests, 1890 * Alfred Binet and Victor Henri on the Psychology of Individual Differences, 1895 * Hermann Ebbinghaus on the Completion Test, 1897 * Stella Emily Sharp on a Test of Mental Testing, 1899 * Clark Wissler on the Inadequacy of Mental Tests, 1901 * Charles Edward Spearman on General Intelligence, 1904 * William Stern on the Mental Quotient, 1912 PART XII: COMPARATIVE PSYCHOLOGY * George John Romanes on Comparative Psychology, 1882 * Conwy Lloyd Morgan on Lloyd Morgan's Canon, 1894 * Jacques Loeb on Associative Memory, 1899 * Herbert Spencer Jennings on the Continuity of Psychological Processes, 1906 PART XIII: FUNCTIONALISM * William James on the Function of Consciousness, 1890 * James Mark Baldwin on the Psychology of Children, 1895 * James Rowland Angell on Functionalism, 1906 * John Broadus Watson on Behaviorism, 1913 PART XIV: LEARNING * Hermann Ebbinghaus on the Learning of Nonsense Syllables, 1995 * Mary Whiton Calkins on the Learning of Paired Associates, 1896 * Edward Lee Thorndike on Animal Learning, 1898 * Robert Mearns Yerkes on the Intelligence of the Turtle, 1901 * Willard Stanton Small on the Maze, 1901 * Edward Lee Thorndike and Robert Sessions Woodworth on Transfer of Training, 1901 * Ivan Petrovich Pavlov on Conditioned Reflexes, 1904 * Wolfgang Kohler on the Insight of Apes, 1917 PART XV: