Investigations of caregiver-infant interaction have increasingly suggested a three pronged thesis about its structure, development and function: a) that such interactions conform to a hierarchically organized, rule governed exchange of message carrying displays (e.g., Stern et al., 1977; Tronick et al., 1979); b) that such exchanges evolve over time "shifting from a prominently biosocial to a more clearly psychosocial level" (Sander, 1977); and c) that it is within the ontogeny of this exchange that the precursors of adult communication are found (Kaye, 1977, 1979; Sander, 1977; Tronick et al., 1979). A central hypothesis of the first prong of this thesis is that caregiver displays which convey contradictory messages violate the rules governing the exchange and that such violations produce negative affect and disturbance in the infant. The goal of this project is to test this hypothesis and alternative hypotheses by evaluating the infants 1 response to simulated maternal depression using appropriate sequential analyses- This display presents the infant with powerful contradictory messages, and sequential analyses produce powerful descriptions of the quality of the infant's response to it