British]ormal zyxwvutsr of Developmental Psychology zyxwvuts (1997), 15,51411 Printed in Great Britain zyxwv 0 1997 zyxwvutsrqponm The British Psychological Society zyxwvut 51 The relationship between belief-desire reasoning and a projective measure of attachment security (SAT) Peter Fonagy, Sheila Redfern and Tony Charman* Subdepartment of Clinical Health Psychology, University College London, Cower Street, London, WClE 6BT UK Recent research into the development of a child’s theory of mind has investigated individual differences in children’s acquisition of the concept. Most of the research that has attempted to delineate this acquisition process has approached the question from a social-cognitive developmental perspective, measuring differences such as family size, mother-child interaction and pretend play. Until now there has been little attempt to test empirically the claims which have been made within the psychoanalytic developmental literature-that measures of affective development, such as attachment, are also likely to be related to the development of a theory of mind and emotional understanding. The main finding of the present study was that attachment security (as measured by the SAT) was a significant correlate of theory of mind competence (as measured by a belief-desire reasoning task), even when the contribution of chronological age, verbal mental age and social maturity were controlled for, in preschoolers and young school-aged children. Research into the development of a child’s theory of mind, in both normal and abnormal populations, has moved from an attempt to answer questions about the type of conceptual structure acquired by children, to an attempt to answer questions about the course or causes of the acquisition of a theory of mind itself (see Baron-Cohen, Tager- Flusberg zyxwvuts & Cohen, 1993; Lewis & Mitchell, 1994, for reviews). Thus, there has been a move away from empirical studies that attempt to delineate the age and conditions under which children demonstrate theory of mind competence (Astington & Gopnik, 1991; Astington, Harris & Olson, 1988; Wellman, 1990), towards studies that investigate individual differences in children’s acquisition of a theory of mind (Dunn, 1994; Dunn, Brown, Slomkowski, Tesla & Youngblade, 1991; Perner, Ruffman & Leekam, 1994). Most of the research that has attempted to delineate this acquisition process has approached the question from a social-cognitive developmental perspective. Perner zy et al. (1994) demonstrated a relationship between family size and development of a theory of mind, with children from larger families passing a false belief task earlier than children from smaller families. They interpreted this finding in terms of the opportunities and incentives that the sibling environment provides as a rich database for constructing a ’* Requests for reprints.