Young infants' visual expectations for symmetric and asymmetric stimulus sequences.

The formation of expectations for visual stimulus sequences was examined in 2- and 3-month-old infants. Two studies were undertaken in which infants' visual fixations were monitored while they viewed predictable and unpredictable sequences of stimuli. Analyses of anticipatory fixations and reaction times (RTs) indicated that by 2 months of age infants can rapidly (within 2 min) form an expectation for the reappearance of an alternate-side event. By 3 months of age, infants rapidly form expectations for asymmetric sequences. Age differences in RT and percent of anticipated pictures suggest rapid development in this domain. Results are discussed in relation to hypotheses of entrainment and global probability matching. It is concluded that young infants quickly develop a crude representation of the spatial, temporal, and possibly numerical parameters of stimulus sequences to anticipate future events. The concept of expectation is central to modern cognitive and learning theories. When an individual forms an expectation, forecasts a future event, and produces anticipatory behavior, he or she demonstrates an ability to represent the environment and act in accordance with the representation rather than the current environmental stimuli alone. Labeled variously as prospective memory (Rovee-Collier & Hayne, 1987; Sherrington, 1906; Wasserman, 1986), preparatory set (Mowrer, 1938), STM priming (Wagner, 1978), or (Capaldi & Verry, 1981; Dodge, 1933; Hull, 1943; Schmidt, 1968), expectations imply active, future-oriented processing of information by mental structures akin to maps, scripts, goals, and plans that impose order on experience and provide a framework for the behavioral anticipation of events (Bolles, 1972; Honig, 1981; Miller, Galanter, & Pribram, 1960; Neisser, 1976). Expectations have received inconsistent attention in early infancy, mostly confined to the domain of infant attention. Following a model proposed by Sokolov (1969), investigators have often proposed that novel-stimulus recovery in a habituation paradigm reflects expectancies. Presumably, the infant forms an internal model of the repeatedly presented familiarization