Developing the ability to anticipate, plan and prepare for significant events is vital to the survival and well being of any organism. Anticipation has been studied extensively in human adults, but has received almost no attention in studies of infants. The long term objectives of this research are to understand the origins of this critical cognitive ability in humans, to evaluate how it changes in the early months of life, and to relate it to other aspects of infant cognitive functioning. A general purpose paradigm for assessing anticipation has been developed for use with infants and has received initial testing. In the procedure, the stimulus pair members, a cue stimulus and a significant stimulus, are separated by fixed intervals of several seconds. Moment-by-moment information on cognitive activity occurring during this and other related intervals is provided by physiological measures such as heart rate and slow wave brain activity, and discrete information is derived from modulated startle reflex probes and overt motor responses. A series of 8 proposed studies are designed to investigate three aspects of importance. The first set of studies elaborates the paradigm and examines new response measures. The second uses the paradigm to investigate development of anticipation in infants 2 to 7 months of age, and evaluates an hypothesis regarding associability among stimulus types. The third group of studies evaluates whether anticipatory responding is associated with effective preparation for events being awaited. Eventually, we plan to determine whether anticipatory capability is a stable quality that relates to general measures of cognitive functioning and to risk factors associated with mental disability. The program will provide comprehensive information on an important but unexplored area of cognitive development.