Effects of Contingent Reinforcement of Actions on Infants' Object-Directed Reaching

The role of contingency learning was examined in 3-month-old infants' reaching movements. Infants in the experimental group experienced 9 min of active training during which they could move their arms in a reach-like fashion to pull and move a mobile. Infants in the control group experienced 9 min of passive training during which they watched a mobile move. Prior to (pre-training) and following the mobile experience (post-training), infants in both conditions were given an opportunity to interact with a rattle placed within and out of their reach. Compared with infants in the control condition, infants in the experimental condition produced reach-like movements more frequently during the mobile experience; they also showed a greater increase in reaching attempts from pre- to post-training assessments with the rattle. These findings show that reinforcement of arm extensions and retractions increases the frequency of infants' reaching behaviors. This result suggests that the reinforcement of components of infants' behaviors may contribute to the successful assembly of these behaviors. This process could help keep infants engaged during the lengthy transition from prereaching to independent reaching.