Negative priming effect after inhibition of number/length interference in a Piaget-like task

According to Dempster, Piagetian tasks have more to do with the child's ability to resist (inhibit) interference than they do with the ability to grasp their underlying logic. Here we used a chronometric paradigm with 9-year-olds, who succeed in Piaget's conservation of number task, to test the role of cognitive inhibition in a priming version of this classical task. The experimental design was such that the misleading strategy 'length-equals-number' to inhibit on the prime (a Piaget-like item with number/length interference) became a congruent strategy to activate on the probe (a subsequent item where number and length covaried). A negative priming effect of 158 ms was observed for the prime-probe sequence. This result confirms that success on Piaget-like tasks (the prime) requires an inhibition process.