Running head: DEVELOPMENT OF MENTAL TRANSFORMATION ABILITIES 1 Development of Mental Transformation Abilities

Mental representation and transformation of spatial information is often examined with mental rotation tasks, which require deciding whether a rotated image is the same or the mirror version of an upright image. Recent research with infants shows early discrimination of objects from mirror image versions. However, even at age 4, many children perform near chance level on more standard measures. Similar age discrepancies can be observed in other domains, including perspective taking, theory of mind, and intuitive physics. These paradoxical results raise the questions of how performance relates to competence, and how to conceptualize developmental change. There may be a common underlying mechanism: the development of the ability to imagine things and mentally transform them in a prospective fashion.