The short-term and longer-term stability of non-completion in an infant habituation task

Abstract

Infants who become too restless, distressed or tired to complete testing sessions are almost invariably excluded from the studies in which they begin participating. In two studies of short-term and longer-term stability in completion extent, we investigated the potential non-randomness of non-completion using an habituation task at 4 months and a problem-solving task at 13 months. In Study 1 ( N=42), short-term stability was established with 4-month-olds. Infants tested on two occasions, separated by 7 days, tended to complete the habituation task at either both testing sessions or neither. Longer-term stability was demonstrated in Study 2 ( N=80). In a problem-solving task at 13 months, infants were awarded points for intentional behaviors, regardless of whether they successfully completed each trial or not. Four-month-olds who did not complete the habituation task were less likely to complete any trials in the problem-solving task at 13 months and performed more poorly in the task than the 4-month completers. These findings demonstrate the non-randomness of non-completion and warn against making assumptions about the population of infants who complete a testing session from the characteristics of those infants who begin the session.