It is difficult to determine exactly when I began this book, as such. However, the research on latent inhibition was initiated in the late 1950s while I was still a graduate student at Cornell University. The next memorable date for measurement was the publication of an article reviewing the latent inhibition literature in the Psychological Bulletin (1973), which appeared in about half of its original length. The conditioned attention theory of latent inhibition was developed later in a series of articles in the Journal of Experimental Psychology: Animal Behavior Processes in the mid-1970s, and then presented more fully in a chapter in Progress in Learning and Motivation edited by G.H. Bower (1981). The idea of developing this material into a book emerged during a sabbatical year at Yale University, 1977–1978, while much of the writing itself was postponed until another sabbatical, 1981–1982, as an Israel-Canada Fellow at Concordia Unversity. To all of these institutions, and to the individuals who were responsible for inviting me, I express my sincerest gratitude, particularly to Allan Wagner and Eugene Rothman.

In addition, throughout the years I have been fortunate to have my research supported by a number of organizations: The National Institutes of Health were particularly encouraging, especially at the early stages of my career with a Career Development Award. Other support has come from the Scottish Rite Schizophrenia Research Program and, in Israel, from the Charles Smith Psychobiology Fund, the Israel National Academy of Science, Israel Research Trustees Foundation (Ford), and Tel-Aviv Unversity.

Similarity of preexposed stimulus and test stimulus

Studies of the influence of stimulus preexposure on subsequent learning usually assume that these effects are stimulus-specific. That is, preexposure to stimulus A should not retard the subsequent acquisition of an association between stimulus B and another event. This assumption is particularly critical if one maintains the idea that the subsequent decrement in the acquisition of the association between A and another event is a result of some previous associative learning during the preexposure phase. Associative learning, by definition, presumes some degree of stimulus specificity. Indeed, the apparent absence of such specificity in the learned helplessness effect, at least in rats (Maier & Seligman, 1976) in which preexposures of a motivationally significant stimulus is administered, by itself, might raise the question whether or not one is dealing with an associative learning phenomenon. For latent inhibition, across different paradigms, the results are quite clear. The decremental effects of preexposure of the to-be-conditioned stimulus on subsequent acquisition of a new association are, without doubt, stimulus-specific.

Such stimulus specificity may be demonstrated in several ways. (1) A within-subject experimental design may be employed whereby the animal is preexposed to stimulus A and tested on both stimulus A and stimulus B. When appropriately counterbalanced, slower learning to the familiar stimulus compared with the novel stimulus serves as evidence for the stimulus specificity of latent inhibition. Such a design was employed by Lubow and Moore (1959), Reiss and Wagner (1972), and Wickens et al. (1983).

Human behaviour is a key to health, and changes in behaviour have a profound influence on patterns of morbidity, and mortality from disease.

This fact is not a new discovery. From the earliest days of human history, behaviour has been the focus of most of the action aiming to prevent and treat illness. Dietary and hygienic prescriptions are embedded in most religions and rituals of mourning are undertaken by the bereaved to help them overcome stress. Societal relations are regulated to strengthen supportive social networks. In the past, links between behavioural change and the course of disease were frequently not well understood, and behavioural action was recommended because of the correlations observed – recommended nevertheless with force and insistence.

The twentieth century brought with it clear evidence of causal links between specific forms of behaviour – including attitudes, action and comprehension – and improvement or deterioration of health states. An impressive amount of literature has been produced over the past decades in this area, and both the public and the scientific community have become acutely aware of the need to influence behaviour if progress is to be made in promoting health, preventing disease, or decreasing suffering of those in whom it has appeared. Insistence that appropriate action be taken has not only stemmed from scientists; government leaders have also addressed the question. The World Health Assembly, bringing together chief health executives from 160 member states, for example, has devoted much of its time to the discussion of this matter.