INFANTS' EARLY MOTOR CONTROL OF REACHING, SITTING AND LOOKING DURING THE A-NOT-B TASK CONTRIBUTES TO ERRORS

Purpose/Hypothesis: The A-not-B task is a well-known developmental paradigm in which young infants often make errors in finding and grasping an object in a second location (the B location) after the object is presented in the first location (the A location) several times. This error has been attributed to immature memory skills, or lack of inhibition ability. The purpose of this study was to analyze infant reaching and eye tracking during the A-not-B task to determine factors contributing to any errors in the final reach.

Number of Subjects: Twenty-four infants, all between 6-8 months old, were recruited from local announcements to parents. All infants could sit and reach independently but were not yet crawling. All infants were typically developing and scored within normal limits on the Bayley III motor screening assessment.

Materials/Methods: Data collection occurred in the home and was videotaped for later analysis. Infants wore a Positive Science eye tracker positioned on their forehead while they retrieved toys through a reaching board with an aperture to one side (the A side) and an aperture to the B side 10 inches away. Infants sat on a 2” cushion to slightly challenge their sitting stability during the testing. The researcher displayed a toy through the A side 5 times, allowing the infant to reach and grasp the toy each time. They then switched to the B side for the 6th reach. Between reaches the infant’s attention was drawn to the center with a sound. The timing of the reaching skills of the infants were measured from the time of toy presentation to touching the toy, along with their gaze to the target locations using Datavyu video coding software. Twenty percent of trials were re-coded by a second coder to establish reliability of the measures.

Results: Infants had the fastest reaching times during the 4th trial to the A location, with an average of 5.48 seconds. The reaching time to the B location (when the toy was switched) averaged 8.64 seconds, a full three seconds longer than the fastest reach to the A location. 10% of the infants looked to the other side where the toy was not hidden during the trial (the wrong side), which likely contributed to the slower reaching time.

Conclusions: Slower reaches during the switched trial could contribute to overall errors in this classic paradigm. In addition to slower reaches, some infants had trouble switching their gaze and also made various other compensatory body postures and movements, all of which may indicate motor control issues contributes to errors in finding the toy in the second location after being primed to the first location.

Clinical Relevance: The A not B task provides a window into the strategies children use to solve problems. Motor skills, including reaching, sitting, and eye movements have a significant impact on infant problem-solving skills. Although developmentalists have postulated an error of locating an object in the A-not-B task is related to immature memory or a lack of inhibition in young infants, we suggest that multiple motor control factors may contribute to the errors frequently displayed during this task.