Illusions

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Illusions

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Title: Illusions A Psychological Study
Author: James Sully
Release Date: February 21, 2006 [EBook #17815]
Language: English
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ILLUSIONS
A PSYCHOLOGICAL STUDY
BY JAMES SULLY AUTHOR OF "SENSATION AND INTUITION," "PESSIMISM," ETC.
THIRD EDITION

LONDON KEGAN PAUL, TRENCH & CO., 1, PATERNOSTER SQUARE 1887
(The rights of translation and of reproduction are reserved)
THE INTERNATIONAL SCIENTIFIC SERIES.
VOL. XXXIV.

PREFACE.
The present volume takes a wide survey of the field of error, embracing in its view not only the illusions of sense dealt with in treatises on physiological optics, etc., but also other errors familiarly known as illusions, and resembling the former in their structure and mode of origin. I have throughout endeavoured to keep to a strictly scientific treatment, that is to say, the description and classification of acknowledged errors, and the explanation of these by a reference to their psychical and physical conditions. At the same time, I was not able, at the close of my exposition, to avoid pointing out how the psychology leads on to the philosophy of the subject. Some of the chapters were first roughly sketched out in articles published in magazines and reviews; but these have been not only greatly enlarged, but, to a considerable extent, rewritten. J. S.
Hampstead, April, 1881.

CONTENTS.
CHAPTER I.
THE STUDY OF ILLUSION.
Vulgar idea of Illusion, 1, 2; Psychological treatment of subject, 3, 4; definition of Illusion, 4-7; Philosophic extension of idea, 7, 8.
CHAPTER II.
THE CLASSIFICATION OF ILLUSIONS.
Popular and Scientific conceptions of Mind, 9, 10; Illusion and Hallucination, 11-13; varieties of Immediate Knowledge, 13-16; four-fold division of Illusions, 16-18.
CHAPTER III.
ILLUSIONS OF PERCEPTION: GENERAL.
Psychology of Perception:--The Psychological analysis of Perception, 19, 20; Sensation and its discrimination, etc., 20, 21; interpretation of Sensation, 22, 23; construction of material object, 23, 24; recognition of object, specific and individual, 24-27; Preperception and Perception, 27-31; Physiological conditions of Perception, 31-33; Visual and other Sense-perception, 33, 34.
Illusions of Perception:--Illusion of Perception defined, 35-38; sources of Sense-illusion, 38-40: (a) confusion of Sense-impression, 40-44; (b) misinterpretation of Sense-impression, 44; Passive and Active misinterpretation, 44-46; Passive Illusions as organically and extra-organically conditioned, 46-49.
CHAPTER IV.
ILLUSIONS OF PERCEPTION--continued.
A. Passive Illusions (a) as determined by the Organism. Results of Limits of Sensibility:--Relation of quantity of Sensation to that of Stimulus, 50-52; coalescence of simultaneous Sensations, 52-55; after-effect of Stimulation, 55, 56; effects of prolonged Stimulation, 56-58; Specific Energy of Nerves, 58, 59; localization of Sensation, 59-62; Subjective Sensations, 62-64.
Results of Variation of Sensibility:--Rise and fall of Sensibility, 64-67; Par?sesthesia, 67, 68; rationale of organically conditioned Illusions, 68, 69.
CHAPTER V.
ILLUSIONS OF PERCEPTION--continued.
A. Passive Illusions (b) as determined by the Environment. Exceptional Relation of Stimulus to Organ:--Displacement of organ, etc., 70-72.
Exceptional Arrangement of Circumstances in the Environment:-- Misinterpretation of the direction and movement of objects, 72-75; misperception of Distance, 75, 76; Illusions of depth, relief, and solidity in Art, 77-81; Illusions connected with the perception of objects through transparent coloured media, 82-84; visual transformation of concave into convex form, 84-86; false recognition of objects, 86, 87; inattention to Sense-impression in Recognition, 87-91; suggestion taking the direction of familiar recurring experiences, 91, 92.
CHAPTER VI.
ILLUSIONS OF PERCEPTION--continued.
B. Active Illusions.
Preperception and Illusion, 93-95.
Voluntary Preperception:--Choice of interpretation in the case of visible movement, 95, 96; and in the case of flat projections of form, 96-98; capricious interpretation of obscure impressions, 99, 100.
Involuntary Preperception:--Effects of permanent Predisposition, 101, 102; effects of partial temporary Preadjustment, 102-105; complete Pro-adjustment or Expectation, 106-109; subordination of Sense-impression to Preperception, 109-111; transition from Illusion to Hallucination, 111, 112; rudimentary Hallucinations, 112-114; developed Hallucinations, 114-116; Hallucination in normal life, 116, 117; Hallucinations of insanity, 118-120; gradual development of Sense-illusions, and continuity of normal and abnormal life; 120-123; Sanity and Insanity distinguished, 123-126.
CHAPTER VII.
DREAMS.
Mystery of sleep, 127, 128; theories of Dreams, 128, 129; scientific explanation of Dreams, 129, 130.
Sleep and Dreaming:--Condition of organism during sleep, 131, 132; Are the nervous centres ever wholly inactive during sleep? 132-134; nature of cerebral activity involved in Dreams, 134-136; psychical conditions of Dreams, 136-138.
The Dream as Illusion:--External Sense-impressions as excitants of Dream-images, 139-143; internal "subjective" stimuli in the sense-organs, 143-145; organic sensations, 145-147; how sensations are exaggerated in Dream-interpretation, 147-151.
The Dream as Hallucination:--Results of direct central stimulation 151-153; indirect central stimulation and association, 153-155.
The Form and Structure of Dreams:--The incoherence of Dreams explained, 156-161; coherence and unity of Dream as effected (a) by coalescence and transformation of images, 161-163; (b) by aground-tone of feeling, 164-168; (c) by the play of associative dispositions, 168-172; (d) by the activities of selective