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Living in a world transformed. Perceptual and performatory adaptation to visual distortion
184
BOOK REvEws
Les diffrrents exposrs contenus darts ce petit ouvrage permettent de s'orienter darts le drbat et facilitent la comprrhension des problrmes. Peat ~tre regrettera-t-on que les positions de Shephard et de Paivio no soient pas prrsentres par les auteurs eux-mSmes? On s'rtonnera peut 6tre aussi que l'Eidrtisme de Jaensch ne soit m~me pas 6voqu6 et que les aspects neuropsychologiques du problrme de rimage mentale aient 6t6 si peu examinrs. Une liste des rrfrrences citres dans les diffrrents exposrs et un index des noms d'auteurs complrtent cet utile recueil. H. HECAEN The Western Aphasia Battery. Edited by A. KERTESZ. Grune and Stratton, Inc, New York, 1982, $49.50, IL S'AGITd'une nouveile version de la batterie prrcrdemment prrsentre (1977). Son but est de permettre rrvaluation des principaux aspects cliniques des fonctions du langage ainsi que de certalnes fonctions non verbales. Les Raven's colored progressive matrices complrtent rexamen. La quantification des rrsultats permet d'rtablir un quotient aphasique d'aprrs les donnres des 6preuves de langage oral et un quotient cortical lorsqu'on inclut les scores des 6preuves non verbales. Etant donn6 que ia premirre version avait 6t6 standardisre, Kertesz a seulement proced6 ~ la comparaison entre l'ancienne et la nouvelle version; les diffrrentes analyses ne montrent pas de diffrrences substantielles entre leurs rrsultats. On trouvera dans de brrves et claires instructions les modes d'applications des tests et la quantification utilisre pour obtenir les deux quotients. Ce matrriel sera certainement trrs utile ~i hombre de centres neuropsychologiques particulirrement lorsqu'on cherchera ~i 6tablir des corrrlations entre les drficits du iangage et les si~ges 16sionnels. H. HECAEN
Living in a World Transformed. Perceptual and Performatory Adaptation to Visual Distortion. H. I)OLEZAL. Academic Press, New York, 1982, 388 pp.--No price given. THIS IS a fascinating book. Imagine being at St John's of Kisses (Greece), a small village on the sea. However, instead of spending normal vacations there, you wear a 3.8 kg modified football helmet to which are affixed prisms which restrict your field of view (115 degrees horizontally x 46 degrees vertically) and reverse the appearance of the external world (in the vertical dimension only). In spite of this attachment you attempt to maintain a normal activity, like walking uphill or downhill, riding a bicycle, swimming, reading and writing letters (to J. J. Gibson). This is the way H. Dolezal, the author, subject and experimenter spent his summer vacations in 1971. When I met him at MIT about 18 months later (he was then tempering his Gibsonian training with the help of R. Held), he had virtually fully recovered. Of course, several people have had a similar experience in the past (e.g., G. Stratton and I. Kohler, to name the best known) but none had reported such a documented and comprehensive study of the effects produced by this radical optical transformation of the visual world. Dolezal~s experiment involved several steps with the attempt to eliminate collateral effects which could have been produced by the weight and size of the helmet and, more interestingly, by the unavoidable limitation of the visual field: this latter variable was studied during an independent 5 day-experiment (by wearing a cardboard tube, 30 cm long, 4.5 cm diameter, in front of each eye). Some of the effects of restricting the visual field (e.g., blundering into door-frames, poor balance, difficulty in performing visually guided actions) had been attributed by previous observers to optical reversal alone. In the Dolezars experiment these effects stabilized after 3(b40 br of wearing the tubes. The main body of the experiment was the 15-day stage with the full equipment, i.e., involving wearing the helmet, limitation of the visual field and phenomenal reversal. The first days were apparently difficult. During self-motion and particularly during head movements, a strong world motion at a faster speed than that of the self mov.ement but in the same direction, was experienced. This resulted in a concurrent paralysing self-instability and nausea. Although the vegetative effects were conquered within a day, it took 87 odd waking hours (or seven days) to notice a clear decrease in the rate of world motion. Near the end of the experiment (after 200 hr), the environment was perceived as stable during head movements, at least for the normal range of velocities. Visuomotor behavior, as could be expected, was severely impaired at the beginning of the experiment. Gross motor actions like swimming or walking adapted first. Actions like reaching or manipulating small objects under visual control took a longer time to become performed competently. Actions such as those "requiring the rapid coordination of eye-head-arm pursuit sequences were never executed satisfactorily in spite of 15 days of practice". More surprising however, was the difficulty to adapt serf-directed movements like eating or getting dressed. Writing under visual guidance with reasonable legibility was not possible until the 8th day, and yet writing movements were felt "visually inappropriate" and "haptically totally unfamiliar and awkward". Another section of the book is devoted to perceptual changes in the appearance of places, objects and of the self. At the initial stage, Dolezal reports a massive perceptual confusion, meaninglessness, indeterminacy, and incongruity.
BOOK REvmws
185
He could not determine where his head was or, at times, would feel it dissociated from the rest of his body, hanging in the air. At other times, he would feel his head at its correct place but resting upside-down. Objects were rarely seen reversed, although the main conflict was between the respective perceived orientations of the head and of the objects. In other words, phenomenal incongruity of the perceived world seems to have been resolved perceptually by selfreversal. However for symbols, letters or words, the perceived orientation of the head was not important. It remains that reading was virtually impossible during the first few days of the experiment. Perceptual adaptation was experienced as a progressive (and incomplete) return to "congruity" of the respective positions of the self and of objects. At an intermediate stage, "hybrid perception" could occur: "the same event" (e.g., shower-water) would appear to move geographically downward or'flow upward' in quick succession depending on the nature of the background visible...". Adaptation was never complete however and tended to be limited to some "acceptance" at the perceptual and cognitive levels as well as at the level of actions, of the disturbing effects produced by the prisms. This book contains many other interesting features. The observer's direct reports are lively and precise. Each chapter involves a complete discussion on the theoretical issues raised by the observations. There is an extensive review of the relevant literature (about 450 references). It is a must for anybody in the field. M. JEANNEROD
BOOK REvEws
Les diffrrents exposrs contenus darts ce petit ouvrage permettent de s'orienter darts le drbat et facilitent la comprrhension des problrmes. Peat ~tre regrettera-t-on que les positions de Shephard et de Paivio no soient pas prrsentres par les auteurs eux-mSmes? On s'rtonnera peut 6tre aussi que l'Eidrtisme de Jaensch ne soit m~me pas 6voqu6 et que les aspects neuropsychologiques du problrme de rimage mentale aient 6t6 si peu examinrs. Une liste des rrfrrences citres dans les diffrrents exposrs et un index des noms d'auteurs complrtent cet utile recueil. H. HECAEN The Western Aphasia Battery. Edited by A. KERTESZ. Grune and Stratton, Inc, New York, 1982, $49.50, IL S'AGITd'une nouveile version de la batterie prrcrdemment prrsentre (1977). Son but est de permettre rrvaluation des principaux aspects cliniques des fonctions du langage ainsi que de certalnes fonctions non verbales. Les Raven's colored progressive matrices complrtent rexamen. La quantification des rrsultats permet d'rtablir un quotient aphasique d'aprrs les donnres des 6preuves de langage oral et un quotient cortical lorsqu'on inclut les scores des 6preuves non verbales. Etant donn6 que ia premirre version avait 6t6 standardisre, Kertesz a seulement proced6 ~ la comparaison entre l'ancienne et la nouvelle version; les diffrrentes analyses ne montrent pas de diffrrences substantielles entre leurs rrsultats. On trouvera dans de brrves et claires instructions les modes d'applications des tests et la quantification utilisre pour obtenir les deux quotients. Ce matrriel sera certainement trrs utile ~i hombre de centres neuropsychologiques particulirrement lorsqu'on cherchera ~i 6tablir des corrrlations entre les drficits du iangage et les si~ges 16sionnels. H. HECAEN
Living in a World Transformed. Perceptual and Performatory Adaptation to Visual Distortion. H. I)OLEZAL. Academic Press, New York, 1982, 388 pp.--No price given. THIS IS a fascinating book. Imagine being at St John's of Kisses (Greece), a small village on the sea. However, instead of spending normal vacations there, you wear a 3.8 kg modified football helmet to which are affixed prisms which restrict your field of view (115 degrees horizontally x 46 degrees vertically) and reverse the appearance of the external world (in the vertical dimension only). In spite of this attachment you attempt to maintain a normal activity, like walking uphill or downhill, riding a bicycle, swimming, reading and writing letters (to J. J. Gibson). This is the way H. Dolezal, the author, subject and experimenter spent his summer vacations in 1971. When I met him at MIT about 18 months later (he was then tempering his Gibsonian training with the help of R. Held), he had virtually fully recovered. Of course, several people have had a similar experience in the past (e.g., G. Stratton and I. Kohler, to name the best known) but none had reported such a documented and comprehensive study of the effects produced by this radical optical transformation of the visual world. Dolezal~s experiment involved several steps with the attempt to eliminate collateral effects which could have been produced by the weight and size of the helmet and, more interestingly, by the unavoidable limitation of the visual field: this latter variable was studied during an independent 5 day-experiment (by wearing a cardboard tube, 30 cm long, 4.5 cm diameter, in front of each eye). Some of the effects of restricting the visual field (e.g., blundering into door-frames, poor balance, difficulty in performing visually guided actions) had been attributed by previous observers to optical reversal alone. In the Dolezars experiment these effects stabilized after 3(b40 br of wearing the tubes. The main body of the experiment was the 15-day stage with the full equipment, i.e., involving wearing the helmet, limitation of the visual field and phenomenal reversal. The first days were apparently difficult. During self-motion and particularly during head movements, a strong world motion at a faster speed than that of the self mov.ement but in the same direction, was experienced. This resulted in a concurrent paralysing self-instability and nausea. Although the vegetative effects were conquered within a day, it took 87 odd waking hours (or seven days) to notice a clear decrease in the rate of world motion. Near the end of the experiment (after 200 hr), the environment was perceived as stable during head movements, at least for the normal range of velocities. Visuomotor behavior, as could be expected, was severely impaired at the beginning of the experiment. Gross motor actions like swimming or walking adapted first. Actions like reaching or manipulating small objects under visual control took a longer time to become performed competently. Actions such as those "requiring the rapid coordination of eye-head-arm pursuit sequences were never executed satisfactorily in spite of 15 days of practice". More surprising however, was the difficulty to adapt serf-directed movements like eating or getting dressed. Writing under visual guidance with reasonable legibility was not possible until the 8th day, and yet writing movements were felt "visually inappropriate" and "haptically totally unfamiliar and awkward". Another section of the book is devoted to perceptual changes in the appearance of places, objects and of the self. At the initial stage, Dolezal reports a massive perceptual confusion, meaninglessness, indeterminacy, and incongruity.
BOOK REvmws
185
He could not determine where his head was or, at times, would feel it dissociated from the rest of his body, hanging in the air. At other times, he would feel his head at its correct place but resting upside-down. Objects were rarely seen reversed, although the main conflict was between the respective perceived orientations of the head and of the objects. In other words, phenomenal incongruity of the perceived world seems to have been resolved perceptually by selfreversal. However for symbols, letters or words, the perceived orientation of the head was not important. It remains that reading was virtually impossible during the first few days of the experiment. Perceptual adaptation was experienced as a progressive (and incomplete) return to "congruity" of the respective positions of the self and of objects. At an intermediate stage, "hybrid perception" could occur: "the same event" (e.g., shower-water) would appear to move geographically downward or'flow upward' in quick succession depending on the nature of the background visible...". Adaptation was never complete however and tended to be limited to some "acceptance" at the perceptual and cognitive levels as well as at the level of actions, of the disturbing effects produced by the prisms. This book contains many other interesting features. The observer's direct reports are lively and precise. Each chapter involves a complete discussion on the theoretical issues raised by the observations. There is an extensive review of the relevant literature (about 450 references). It is a must for anybody in the field. M. JEANNEROD