In this book, I have attempted to evaluate critically the very large literature which has accumulated in the area of biofeedback over the past 10-15 years. As might be expected in any area of psychology with clinical possibilities, the literature divides itself into two main categories-fundamental research studies and therapeutic studies. It is now apparent that the clinical applications of biofeed­ back have far outstripped their fundamental research bases, with the inevitable result that the initial wave of enthusiasm may be replaced with an unnecessarily severe skepticism. Either extreme position is unjustified. Biofeedback does rep­ resent an important new approach to the elucidation of the role played by internal systems in the adjustment of the organism to its environment. But its potential will only be revealed if its use in practice is soundly based on fundamental research. There are promising signs that this is being realized so that there is cause for optimism. Aubrey J. Yates Perth, Australia A Note on the References With the exception of no more than two or three papers, all the references in this book have been obtained and read. However, many of them were published in journals which will not be readily accessible to the reader who may be interested in consulting more directly particular articles which attract his attention.