One of the first documented classical conditioning studies in infants was conducted by Watson and Rayner (1920). In their early studies, they demonstrated that fear can be learned through conditioning presented through repeated pairings of a neutral stimulus (e.g., white rat) with a loud noise (Watson & Rayner, 1920). In another study, 12 full-term infants as young as 3 months of age showed greater response magnitude to the CS+ compared to the CS− as indexed by skin conductance response (SCR) (Ingram & Fitzgerald, 1974). Results from these studies were among the first to demonstrate the effects of simple fear conditioning in infants at early stages of development.
While in the past decade there has been a rekindling of interest in research examining the emergence of fear conditioning in children, there are still relatively few fear conditioning studies in child and adolescent populations. Following these early studies on fear conditioning in children, research in this field has been hindered by ethical and methodological considerations. Questions in regard to the aversive nature of the UCS required to produce fear responses in developmental populations or the appropriate measures of fear conditioning and extinction, have always been an integral part in the scientific effort to study fear conditioning developmentally. In the following sections, we will review the most commonly used UCS and CR in these fear conditioning studies, after which we will summarize the major findings for fear conditioning and extinction in children and adolescents. A summary of sixteen fear conditioning studies conducted in normative and anxious samples of children and adolescents using a discrimination fear conditioning paradigm is presented in Table 1.