Inertial-magnetic sensors for assessing spatial cognition in infants.

This letter describes a novel approach to the assessment of spatial cognition in children. In particular, we present a wireless instrumented toy embedding magneto-inertial sensors for orientation tracking, specifically developed to assess the ability to insert objects into holes. To be used in naturalistic environments (e.g., day cares), we also describe an in-field calibration procedure based on a sequence of manual rotations, not relying on accurate motions or sophisticated equipment. The final accuracy of the proposed system, after the mentioned calibration procedure, is derived by direct comparison with a gold-standard motion tracking device. In particular, both systems are subjected to a sequence of ten single-axis rotations (approximately 90°, back and forth), about three different axes. The rms of the angular error between the two measurements (gold-standard versus proposed systems) was evaluated for each trial. In particular, the average rms error is under 2°. This study indicates that a technological approach to ecological assessment of spatial cognition in infants is indeed feasible. As a consequence, prevention through screening of large number of infants is at reach.