To See But Not to See : A Case Study of Visual Agnosia

Text in English. 124 pp. Corned folded, some shelf wear. Brain damage may sometimes cause remarkably specific impairments in human behaviour. One very rare and specific impairment is the failure to recognise everyday objects by sight, a problem which is termed "visual agnosia". In this book, Drs Humphreys and Riddoch discuss the fascinating case of a patient, John, who suffered visual agnosia after having a stroke. After the stroke, John's visual world seemed strange and unfamiliar; formerly well-known objects no longer made any sense, and he did not know what to use them for. This problem was not confined to objects - he also had difficulty recognising faces or his immediate environment. He could no longer recognise his wife's face, his own face in the mirror was unfamiliar, and his surroundings appeared strange, so that he got lost when trying to find his way around. Yet, other aspects of John's behaviour were quite unaffected. He could recognise objects by touch or by the sounds they made, and his general knowledge and intellect were perfectly good, What makes the case even more intriguing is that many of the "components" that make up our ability to recognise objects visually seemed intact. John could draw objects from memory, indicating a good knowledge of what the objects should look like. He could also copy the objects he failed to recognise, indicating that, in some respects, he could see. Apparently, John was able to "see" but not to "recognise". The book considers John's case from the point of view of current psychological theories of visual recognition, and from a review of other previously documented cases. It goes on to consider the implications of John's problems for understanding how we might normally recognise objects, drawing on investigations of his impairments. The book also includes chapters contributed by John and his wife, which graphically illustrate the nature of his problems and the characteristics of his changed visual world. The book demonstrates how our knowledge of a complex process, such as visual recognition, can be enriched by detailed case studies of recognition impairments. To See But Not to See is likely to become a key reference for those concerned with understanding how vision is implemented in the brain, and will be of interest to anyone concered with the scientific understanding of the mind.…