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Blind Vision: The Neuroscience of Visual Impairment.

Blind Vision: The Neuroscience of Visual Impairment. Zaira Cattaneo and Tomaso Vecchi. Cambridge, MA: MIT Press, 2011, 269 pp., illustrated, $36.

This book's title phrase, Blind Vision, is a concise summary of the book's contents, which comprise arguments and evidence that people who cannot see have the same kinds of perceptions, mental imagery, and knowledge as people who can see. Blindness is a big nuisance, but in most areas of everyday life it doesn't much change what people can notice, what people can remember, or what people can do. Authors Cattaneo and Vecchi take on the enormous task of synthesizing 50 years of cognitive psychology and cognitive neuroscience research conducted with people who are blind. Like the best cognitive psychology, the work examines the cognitive processes and memory representations that underlie the skilled performance of functionally important tasks in everyday life. Like the best neuroscience, the work synthesizes evidence-based findings on the major brain imaging (fMRI and EEG, for example) and brain assessment (TMS, for example) methods that are used to localize brain regions that mediate perception and cognition, and it summarizes what happens to those brain regions when vision is absent or impaired. Cattaneo and Vecchi provide a comprehensive and balanced view of the cognitive neuroscience of blindness, acknowledging its current limitations and highlighting its potential applications. In doing so, they set the stage for others to apply the lessons gained to help learners learn and teachers teach.

In terms of topical content, Blind Vision is about how perception, imagery, knowledge, working memory, and spatial cognition are used to accomplish the tasks of daily life that involve locomotion, wayfinding, and object identification and manipulation; as well as academic tasks including those involved in reading, science, and math. Wherever possible, the authors compare total blindness, low vision, and typical vision, and they identify perceptual and cognitive skills (tactile picture identification, for example) that appear to vary based on the age at onset of blindness and those (tactile discrimination, for example) that do not. And although it is not a major part of the book, the authors make an important contribution to the literature by synthesizing what is known about monocular vision-which, in our view, is an important category of low vision that is often overlooked by researchers and teachers alike.

ORGANIZED BY THEME

Cattaneo and Vecchi organize their topics around four major themes: Amodal information, sensory compensation and substitution, spatial imagery (not visual imagery), and brain plasticity. These themes form the core of the book and are mentioned in most of the chapters. We elaborate on each below.

Amodal information

Amodal information (meaning "without modality") specifies properties of objects and events that are common in multiple senses. Temporal properties of events like rhythm, tempo, duration, and synchrony can be perceived by listening, looking, and touching. Consider, for example, that the cadence of a person's gait can be heard as well as seen by others; the viscosity of a liquid can be heard when it is poured and felt when it is stirred; and whether a smooth plate is metal or wood can be felt when it is touched and heard when it is struck with a mallet. Different modalities of information specify the same properties, but they are not completely redundant and vary in their precision, breadth of field, and speed. Cattaneo and Vecchi point to the evidence that when amodal information is available, people pragmatically select the mode that is "easy," in the sense that it is best matched to a given task. For example, pedestrians tend to rely on vision for guidance in street crossings, because "with a single gaze we can simultaneously embrace an enormous amount of information, and our foveal acuity allows us to focus on very detailed characteristics of what we are perceiving" (p. 4). Similarly, sculptors working in a medium such as stone rely on touch to detect minute surface flaws that go unnoticed by vision (Ponchillia, 2008). Despite intermodal differences in what is perceived, the value of amodal information is illustrated by such examples as blind pedestrians routinely and safely crossing streets based on what they hear and what they touch.

Sensory compensation and substitution

The examples above also illustrate the authors' second major theme: In circumstances in which one sensory mode is absent, some of the other senses can substitute for it. This substitution may occur with or without an aid such as a long cane or an electronic device. The concept of sensory substitution has been widely used in the design of electronic devices for travel (accessible pedestrian signals and the MiniGuide, for example), and for reading and browsing the web (examples include JAWS and the Kurzweil-NFB reader). Cattaneo and Vecchi's focus, however, is on unaided sensory substitution and the question of whether this involves sensory compensation for vision loss. That is, the authors consider the question: When vision is missing, do the other senses compensate by improving their speed of processing, the complexity of what they can perceive, and/or their sensitivity to small changes (that is, better sensory acuity)? The idea of sensory compensation has a long history in popular culture (see, for example, H. G. Wells' 1904 story "The Country of the Blind"). Cattaneo and Vecchi review the cognitive psychology evidence and make a case for sensory compensation by pointing out the specific perceptual and cognitive skills for which the evidence suggests that people who are blind may excel and other skills in which they may tend to struggle. The authors attempt to make sense of these patterns by identifying regions of the brain that might be responsible for such differences, and they consider how visual experiences prior to blindness may affect sensory compensation.

Spatial imagery

Cattaneo and Vecchi review the evidence for the importance of imagery for learning and memory, reasoning, and school performance in areas such as math and science, wayfinding, and many other aspects of daily life. They review a wealth of cognitive psychology research about imagery, including research with congenitally blind people, concluding that "blind individuals are able to generate mental representations containing accurate spatial relations and full of nonvisual sensory details" (p. 79). Cattaneo and Vecchi emphasize research about the mental manipulation of images such as in the classic studies by Shepard and Metzler (1971). They link the cognitive psychology findings about imagery to brain science research, showing strong similarities in brain activation when objects and events are seen and when they are imagined (Georgopoulos, Lurito, Petrides, Schwartz, & Massey, 1989). How is it, the authors ask, that people born without vision can have images similar to those of sighted people and can manipulate those images in similar ways? Their answer is to theorize that imagery is primarily spatial, not visual. They also examine the evidence that blindness imposes limitations on imagery processes in situations in which images are necessarily based on sequential haptic exploration, such as in the examination of large objects and tactile maps.

Brain plasticity

Experience continuously changes the structure and function of the brain over one's life span, the details of which are becoming increasingly apparent through the brain imaging and brain assessment techniques discussed throughout this book. Although brain science has a long way to go, the basics are becoming apparent. People who depend on nonvisual information become better at processing it, and differences in processing are reflected in functional or anatomical differences in brains or both. When some portions of the cerebral cortex do not receive input from their typical sensory modalities, then the other modalities recruit some of that neglected cortex and use it. For example, while the visual cortex of people born with vision participates in how people hear events and feel objects, it participates even more so for people born without vision.

Some brain changes appear to be more durable than others. For example, Cattaneo and Vecchi review the literature about the restoration of sight to people with early-onset blindness who had no useful vision beyond the ability to perceive light. Although they conclude that it is too early to make definitive conclusions about the permanency of brain changes (and that rehabilitation training may have an important role to play in the "education of vision"), some aspects of visual perception appear to improve much less than others during the years after the restoration of a typical retinal image. Interestingly, Merabet and colleagues (2008) demonstrated that for sighted people taking part in tactile training activities (such as braille instruction and tactile domino games) for five days while continuously wearing a blindfold, their occipital cortexes were recruited for processing tactile information. This effect disappeared within 24 hours of removing the blindfold, and it did not occur at all when sighted people wore blindfolds for only six hours for each of five days.

These findings seem relevant to discussions about (and for encouraging research about) such practices as blindfolding all students with low vision during their rehabilitation instruction, a practice that is popular in some rehabilitation agencies in the United States.

There are relatively few books about blindness. Some are autobiographical memoirs, for example, Helen Keller's (1903) The Story of My Life and Geerat Vermeij's (1996) Privileged Hands: A Scientific Life. Some are edited volumes consisting of chapters written by different scientists or educators that each focus on topics within the authors' particular areas of expertise. Recent examples are Wiener, Welsh, and Blasch (2010, Foundations of Orientation and Mobility); Rieser, Ashmead, Ebner, and Corn (2008, Blindness and Brain Plasticity in Navigation and Object Perception); and Heller and Ballesteros (2006, Touch and Blindness: Psychology and Neuroscience).

THE INTEGRATION OF COGNITIVE PSYCHOLOGY WITH BRAIN SCIENCE

Other than the work of Cattaneo and Vecchi, we can think of only three scientific monographs that were written in their entirety by the same author or authors. Selma Fraiberg's (1977) Insights from the Blind: Comparative Studies of Blind and Sighted Infants described her original findings. She reported the longitudinal methods she used to assess the cognitive, motor, and social development of 10 infants who were totally blind, together with observations of their sighted peers. Her observations started when the infants ranged from 3 to 11 months of age and ended when they ranged from 3 to 5 years of age. The babies she observed acquired some skills later than did peer-aged babies who could see. Much like Piaget's observations about the cognitive development of sighted infants, Fraiberg's have inspired generations of scientists and educators interested in the development of children with blindness.

The other two monographs synthesize research that had been published previously. David Warren's (1977), Blindness and Early Childhood Development (together with its 1984 revision), synthesized what was known about age-related changes in children who were blind. Mark Hollins' (1989), Understanding Blindness: An Integrative Approach, synthesized research about the cognition and learning of adults with blindness or severe visual impairment. Blind Vision: The Neuroscience of Visual Impairment joins these earlier works and surpasses them, by integrating cognitive psychology with brain science.

Scientific research comes in many varieties. We close this review by identifying three. "Basic research" aims to describe how something works, and "applied research" aims to solve particular problems as they exist in a particular set of circumstances. "Use-inspired research" (Stokes, 1997) bridges the two and is aimed at understanding how things work in order to pave the way for future researchers to work out the critical applications. Blind Vision does a fine job synthesizing basic research from the cognitive and brain sciences that relates to how daily living and academic tasks are accomplished by people who are blind. We think Blind Vision is use-inspired, and that it will play an important role in paving the way for others to work out the practical implications of the research for teachers and learners.

REFERENCES

Fraiberg, S. H. (1977). Insights from the blind: Comparative studies of blind and sighted infants. New York: Basic Books.

Georgopoulos, A. P., Lurito, J. T., Petrides, M., Schwartz, A. B., & Massey, J. T. (1989). Mental rotation of the neuronal population vector. Science, 243, 234-236.

Heller, M. A., & Ballesteros, S. (Eds.). (2006). Touch and blindness: psychology and neuroscience. Mahwah, New Jersey: Lawrence Erlbaum Associates.

Hollins, M. (1989). Understanding blindness: An integrative approach. Hillsdale, NJ: Lawrence Erlbaum Associates.

Keller, H. (1903). The story of my life. New York: Doubleday, Page and Company. Merabet, L. B., Hamilton, R., Schlaug, G., Swisher, J. D., Kiriakopoulos, E. T. et al. (2008). Rapid and reversible recruitment of early visual cortex for touch. PLoS ONE, 3(8): e3046, doi:10.1371/ journal.pone.0003046.

Ponchillia, P. E. (2008). Nonvisual sports and art: Fertile substrates for the grown of knowledge about brain plasticity in people who are blind or have low vision. In J. Rieser, D. Ashmead, F. Ebner, & A. Corn (Eds.) Blindness and brain plasticity in navigation and object perception. New York: Erlbaum.

Rieser, J. J., Ashmead, D. H., Ebner, F. F., & Corn, A. L. (Eds.). (2008). Blindness and brain plasticity in navigation and object perception. New York: Erlbaum.

Shepard, R. N., & Metzler, J. T. (1971). Mental rotation of three dimensional objects. Science, 171, 701-703.

Stokes, D. E. (1997). Pasteur's quadrant--Basic science and technological innovation. Washington, DC: Brookings Institution Press.

Vermeij, G. (1996). Privileged hands: A scientific life. New York: W. H. Freeman. Warren, D. H. (1977; 2nd ed.: 1984). Blindness and early childhood development. New York: American Foundation for the Blind. Wells, H. G., & Sherborne, M. (Ed.). (1996). The country of the blind and other stories. New York: Oxford University Press.

Wiener, W. W., Welsh, R. L., & Blasch, B. B. (Eds.). (2010). Foundations of orientation and mobility (3rd ed., in two vols.). New York: AFB Press.

John J. Rieser, Ph.D., professor, Psychological Sciences, Department of Psychology and Human Development, Vanderbilt University, Peabody College, 230 Appleton Place, Nashville, TN 37203; e-mail: <j.rieser@vanderbilt.edu>. David A. Guth, Ph.D., professor, Blindness and Low Vision Studies, College of Health and Human Services, Western Michigan University, 1903 West Michigan Avenue, Kalamazoo MI 49008; e-mail: <david.guth@wmich.edu>.
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Author:Rieser, John J.; Guth, David A.
Publication:Journal of Visual Impairment & Blindness
Article Type:Book review
Date:Jul 1, 2012
Words:2322
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