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Synesthesia comes from the Greek syn (meaning union) and aisthesis (sensation), literally interpreted as a joining of the senses. Synesthesia is an involuntary joining in which the real information from one sense is joined or accompanies a perception in another. Dr. Cytowic reports extensive research into the physical, psychological, neural, and familial background of a group of synesthets. His findings form the first complete picture of the brain mechanisms that underlie this remarkable perceptual experience. His research demonstrates that this rare condition is brain-based and perceptual and not mind-based, as is the case with memory or imagery. Synesthesia offers a unique and detailed study of a condition which has confounded scientists for more than 200 years.

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1 Introduction 1.- Historical Background.- How This Work Got Started.- Criticism of Experiential Responses.- The Ghost in the Machine.- How Does Mind Arise from Matter?.- How Materialism Transcends Itself.- Synesthetes as Cognitive Fossils.- 2 Synesthetes Speak for Themselves 23.- Synesthetes Speak for Themselves.- Similarity of Stories.- Range of Synesthetic Performance.- Synesthesia as an Unelaborated Percept.- Validity, Constancy, and Limits to Manipulation of the Parallel Sense.- Psychological Influence and Stigma.- What Is Synesthesia Good for?.- Familial Cases.- 3 Theories of Synesthesia: A Review and a New Proposal 61.- Diagnostic Criteria for Synesthesia.- What and Where is the Link?.- Theories of the Mechanism of Synesthesia.- Proposal for a Synesthetic Mediator.- Operationalizing the Theories of Synesthesia.- 4 Overlaps: To What Is Synesthesia Similar? 91.- Phenomena Similar to Synesthesia.- Supporting Evidence for Anatomical Localization.- A Disconnection Syndrome for Synesthesia: Analogy to Migraine Theory.- Relation of Synesthetic Perceptions to Klüver´s Form Constants.- Conclusion.- 5 The Neural Substrates of Synesthesia.- Conceptualization of Neural Tissue.- Achromatopsia.- Knowing and the Limbic System.- The Triune Brain.- Conclusion.- 6 Synesthesia and Language.- The Semantic Differential.- Language and Cross-Modal Associations.- Synesthesia as a Disconnection.- Language and Consciousness.- Language and Electrical Stimulation of the Brain.- 7 Synesthesia and Personality.- Number Forms.- Synesthetic Forms.- Psychological Parameters of Synesthetes.- Family Cases (Pedigrees).- Clairvoyance and Other Unusual Experiences.- 8 Synesthesia and Art.- Geometry, Color, and Form.- Divine Proportion and Dynamic Symmetry.- Color.- Art and Synesthesia.- 9 What is Real?.- Colored Illusions: Color Constancy and Colored Shadows.- Retinex Theory of Color Vision.- Phantom Vision and Blindsight.- Optic Imagery and the Gestaltists.- Microgenetics.- 10 Conclusions.

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