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understandably, for those of honey bees, which receive a rather more intensive examination. The examples given of the nests of birds illustrate the variety of nest shapes and materials used, but the constructions of male bower birds and the nest mounds of megapodes are described in some detail together with recent experimental work. Among the mammals, examples are given of both bur- rowers and nest builders but it is the dams and lodges of beavers which dominate this final section. The text is supported throughout by good line drawings and an ample (occasionally more than ample) quantity of photographs, mostly of a high standard. A small number of workers in the field of animal construction are men- tioned in passing but there is no bibliographic index.

Each new architectural item in the book is generally preceded by a brief sketch of the animal concerned to give the reader a more general biological background. The presentation is therefore in the nature of glimpses at the private lives of animals with particular reference to the constructions they produce. These cameos are sometimes ornamented with evidence from experiments which reveal processes underlying construction and it is these that form the most satisfying parts of the book. The non-specialist reader will naturally think of human parallels in construction, and such an interest might have been channelled into a greater understanding of true similarities and differences in construction between species, Little consideration, however, is given to the convergent solution of common construction problems by animals, or to the development of any other archi- tectural themes that might have served to draw together the diverse examples. Instead the reader is asked little more than to delight in each of a great variety of animals in the same way that the author undoubtedly does.

M. H. HANSELt. Department of Zoology, University of Glasgow, Glasgow.

Constraints on Learning. By R. A. HINDE & J. STEVENSON- Hrt<DE. Academic Press (1973). Pp. xv q- 488. s

The great learning theories are dying. In his introduction to this volume, Hinde speaks of that period of 'heroic optimism' during the thirties and forties, when it seemed possible to construct comprehensive behaviour theories of great generality. While most experimental psycho- logists stuck to rats and pigeons, learning in rather proscribed conditions, it was possible to keep the faith.

The break-up has come in part from without--the increasing data on learning during development in a wide variety of animals introduced by ethologists. It has also come from within, for experimental psychologists have extended the conventional learning paradigms and, eschewing over-automation, have begun watching what actually happens in shuttle-boxes and Skinner boxes.

This book invites immediate comparison with that edited by Seligman & Hager. They complement each other well. The earlier work consists of reprinted papers which, with good linking material, traces some of the history of the new, biological approach to learning. Hinde & Stevenson-Hinde's book develops the various themes in a range of reviews presented originally as papers at a conference in Cambridge. An introduction was pre-circulated and also a number of the manuscripts.

Hinde himself provides the introduction in which he addresses himself to the whole range of the phenomenon of learning constraints. I react to this as I do to so much of his writing. It takes a couple of readings to catch the

argument in places, but once caught one feels there is nothing much left to say. No ground is unturned or concept unweighed: this fifteen page essay is a remarkable piece of work.

A book of this nature is very difficult to review ade- quately. Its twenty-three chapters cover an immense range of concept and experiment. I found almost all of them good reading, but there is no point in producing a simple catalogue here.

The editors provide some Structure with a series of interspersed editorials before each group of papers. The first group concerns the role of sensory input and constraints on stimulus accessibility. There is an excellent piece of straight ethology from Baerends & Kruijt who describe field experiments on the responsiveness of herring gulls to models of eggs. Their 'titration' method, whereby the stimulus value of a model can be measured by pairing it with others of known effectiveness, is elegant and productive. They find conclusive evidence that the same stimulus is evaluated differently by the bird depending on the motivational context. Green eggs are retrieved back into the nest in preference to red, but red eggs are eaten in preference to green.

In the majority of such cases, and few have been analysed as fully as this, learning can overcome a natural preference provided a suitable reinforcement is arranged, but such preferences form a marked constraint. Later in this section Bateson discusses the internal influences affecting the responses of young birds to parent objects. Some of these responses conform to conventional learn- ing criteria, others do not. The bird arrives in the situation pre-disposed to respond to conspicuous objects (and evidence from sexual imprinting studies not dealt with here would suggest that some characteristics of the preferred objects are already specified to the bird); it also tends to move and orientate itself so as to maximize its chance of contacting such objects. Bateson's work is not only relevant to the analysis of learning, but ex- emplifies the way ethological analysis must itself proceed.

The physiological basis of constraints on responsive- ness has shown the greatest advances with the visual system. Blakemore's essay describes the remarkable recent extensions of Hubel's & Wiesers work on eat visual units. These units in the striate cortex have some inherent bias, but this can be sharpened or modified by the type of objects to which the kitten is exposed in early life. Blakemore provides a clear demonstration of a sharp critical period for this modification: the units are insensitive save from 4 to 12 weeks of age. During this time quite short exposures to horizontal stripes, for example, will bias a large proportion of the units. It is interesting to speculate on the relevance of such findings for imprinting work. Admittedly parent objects are complex and cannot be readily analysed into horizontal and vertical components. Is the young bird imprinting at a time when its visual units are labile? Could its subsequent attachment be due in part to biassed per- ception ?

In its second group of papers the book moves on to examine aspects of stimulus relevance, i.e. whether particular reinforcements are more likely to be' associated with particular types of preceding events. It was this phenomenon so vividly revealed by Garcia's group in their early papers, which opened up one major crack in the edifice of learning theory. Rats preferentially associate taste stimuli with subsequent sickness and further, can make such associations with prolonged delays between stimulus and reinforcement. It seems highly probable that this capacity results from a genetic predisposition.

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However, in an earlier chapter Mackintosh points out that animals have ample opportunity to learn to ignore stimuli other than taste where gastric sensation or perhaps 'general well being' is concerned.

In this section there are chapters by Hogan on the development of food recognition by young chicks, and McFarland who reviews the literature on 'stimulus relevance' of the type outlined above. McFarland successfully brings together work of the Garcia type on learnt aversions, with the literature on the develop- m e n t of specific appetites. Rats appear to learn an aversion to their familiar diet if they become unwell.

The third section of the book concentrates upon constraints on reinforcement. In brief, many studies have now shown that only within certain limits is it possible to alter response frequency by manipulating reinforcement. There is reinforcement relevance as well as stimulus relevance.

Stevenson-Hinde provides a most useful review here. and there are chapters by Shettleworth and Glickman which describe their attempts, and they are the first of their type, to explore the effects of reinforcement fol- lowing the performance of a whole variety of spontane- ously emitted responses. In the hamster, Shettleworth finds that food reinforcement will increase the frequency with which rearing, digging and scrabbling on the surface are performed. It has no effect on face washing. The affected patterns are all part of the natural food-seeking repertoire, face washing is not.

We need more systematic exploration of this type. As Stevenson-Hinde and Shettleworth point out, even if we are successful in altering the performance frequency of a response by extraneous reinforcement, the normal factors which influence its performance will also be present. We may learn something about the latter by manipulating the former and such information may interest ethologists. It is important to know how far animals have 'voluntary' control over the performance of ritualized display patterns which are often considered to be rather rigidly bound to a particulr underlying motivational state.

Sevenster's contribution in this section of the book on reinforcement is relevant here. He gives a slightly more detailed account of work he has published elsewhere concerning aggressive and sexual reinforcement for an operant in sticklebacks. His results suggest that males do not have much freedom of action. They cannot dissociate the motor patterns involved in biting a rod (the operan0 from aggressive arousal. Following sexual arousal the stickleback cannot bring itself to bite again for a minute or two, and in fact shows zig-zag courtship movements to the rod.

This observation brings us to one of the most striking contributions in this whole volume, that of Moore on the phenomenon of 'autoshaping'. I f a pigeon is given inter- mittent food or water reinforcement in a Skinner box and at the same time a key is illuminated, it soon ap- proaches and begins to peck it, i.e. it autoshapes its behaviour even though this makes no difference to its reinforcement. This, in itself, contravenes one of the most strict of Skinnerian laws, but we were perhaps prepared for this from the Breland's 'Misbehavior of Organisms'. Perhaps more striking is the evidence which Moore presents utilizing the old and still valuable ethological technique of watching the animal. If it is paired with food reward, the key is pecked by the pigeon using the open bill which closes on impact as if to grasp a grain of food. With water reward the slightly

open bill is held against the key and the familiar pigeon drinking movements ensue.

Moore's argument expressed in a deliberately provoca- tive manner is essentially that all conditioning is classical. Pavlov's dog salivates to its bell; Moore's pigeons eat or drink their keys. Operant conditioning is a myth. One's view on this judgment will depend, I suppose, on how far much store was reposed in the concept to begin with. I have heard the view expressed that autoshap.ing renders meaningless all the work of the Skinnenan school. This is far too extreme a view. As a technique for studying learning it remains indispensable and, whatever our theoretical stance, we shall certainly be none the worse for this fuller realization of what it involves. I admired Jenkins' paper, which follows Moore's here, in which he attempts to incorporate some aspects of autoshaping into a modified operant theory, but I was less wholly convinced. For one relative outsider at least, a Skinner box will never look the same again.

The final two sections of this volume are largely concern- ed with data drawn from human studies. Connolly's inter- esting paper on the classification and development of hand movements in children is the most easily related to the animal studies. He can observe constraints on learning which arise from the need for physical growth and experience of sensory-motor relationships as the child puts together the various sub-routines necessary for acquiring new manual skills. In a characteristically shrewd comment on this process, McFarland points out that those motor skills are easiest learnt which provide during each sub-routine immediate feedbaek of the result. In this way errors can be corrected at source. Some skills cannot satisfactorily be broken down into units andthough the overall result is obviously wrong, we have trouble pin-pointing our error source. Compare riding a bicycle and its instant warning of wobble with learning to improve a golf swing.

Perhaps because I know much less of their back- ground I find some of the other papers more difficult to judge. Some of the concepts particularly those de- riving from Piaget's ideas on developmental stages, seem insubstantial. Critical experiments with human children which might take the concept of developmental stage further than mere description are difficult.

John Hutt provides a concluding chapter which critically examines most of the contributions to these sections. He makes some good points and tries, with partial success, to focus attention on neurological variables which may underlie human behavioural development.

This volume represents an admirable and highly stimulating survey of a diverse field. I find it encouraging that the psychological and ethological approaches to behaviour have never felt closer. We can now study the ethology of learning in a truer perspective. If universal learning theories are dead we have a chance to replace them with concepts more securely based in the biology of the animals we study.

AUBREY MANNING Department of Zoology, University of Edinburgh.

Ultrasonic Communication by Animals. By GILLXAN SALES & DAVrD PYE. London: Chapman & Hall, Ltd. Price s

Sales' and Pye's working definition of communication is that of the communications engineer; hence their selection of studies of ultrasound in animals, in this