The Development of Vision for Action in Toddlers: The Posting Task

Visual information related to perception of objects and action on objects is processed along two neural pathways known as the dorsal and ventral streams. The dorsal stream works as the “how” or “where” system, processing information related to action. The ventral works as the “what” system processing information relevant to perception. A task previously used in neuropsychology to assess dorsal and ventral stream functioning is known as the posting task and involves inserting a flat, rectangular object into a slot. Recent research used a modified version of the posting paradigm to examine dorsal stream development in toddlers. Street and colleagues (2011) found significant changes in the ability to align a disc with a slot between 18- and 24-months. The younger children failed while the older group easily succeeded. The current study examines the developmental trajectory throughout this time period. Sixteen children were recruited for a longitudinal study. Each child participated in a posting task experiment once a month from 16-months to 24-months of age. The resulting data enabled examination of both the group trajectory and individual differences. Results revealed a linear pathway toward mastery of this task. As in the previous study, the younger children experienced difficulty in aligning the disc with the slot. However, performance improved gradually throughout the 8-month study. The majority of the children were successful by 22-months of age. The developmental changes seen in this study suggest underlying changes in dorsal stream functioning. These results provide insight into a critical developmental stage in a child’s life.