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Book Review: Addition and Subtraction: A Cognitive Perspective

Sound reception is covered under two headings: receptor mechanisms and central nervous processing. The study of vertebrate receptor mechanisms is currently a very dynamic field for many reasons, not least of which are the recent discovery of sound emission from normal ears and the successful recording of single receptor activity. Thus Ashmore and Russell’s review of hair cell physiology (the receptors common to vertebrate ears) is timely and includes much of the present thinking on the nature of active processes in the cochlea. It is a pity, however, that the three important findings included as footnotes were unavailable for discussion at the time of writing. Insects, by contrast, use a bewildering range of specialized body parts for hearing, such as legs, antennae, wings, abdominal regions and mouth parts. The receptor section also includes mammalian auditory nerve activity and localization cues. Neither seems to fit easily into this section, but both are very necessary and would be inappropriate elsewhere, especially since many localization cues are of peripheral origin. The concentration on the mammalian auditory nerve is remedied to some extent by a more comparative treatment in the central processing section, which also includes chapters on insects, non-mammalian vertebrates and mammals. Auditory space coding in the vertebrate is considered by Knudsen. Again we have a very active field, inspired to a large extent by the demonstration by this author and his colleagues of a precise auditory space map in the owl. However, the implicit jump made here from mammalian data obtained mainly under closed-field conditions to space maps in the owl may not be justified. (Recent studies on mammals using free stimuli should shed light on this question.) Finally two special aspects are considered: underwater bioacoustics and echolocation. The single chapter on underwater acoustics seems inadequate until one considers that the authors have managed, in 60 pages, to encompass not only the physics, but also the reception and generation of sound by animals ranging from invertebrates to whales! The editor states that his major aim is to demonstrate the general nature of the problems and their solutions. Certainly the comparative aspects are emphasized in some chapters and are enhanced by the juxtaposition of others. The generality of many problems and solutions is apparent, but on the other hand the insects particularly seem to have many solutions to the same problem. This is not a book for light reading, it provides detailed appreciations of widely different and specialized bodies of literature and should prove invaluable as a reference work for a wide readership. A. R. Palmer