Poster #161 - The development of infant reaching to tactile stimuli on the face

• In Event: 3-106 - Poster Session 11
  In Poster Session: PS 11 Section - Perceptual, Sensory, Motor

Integrative Statement

Reaching to tactile stimuli on the face enables infants to perform adaptive actions such as scratching an itch or touching a source of discomfort, which can alert parents and physicians to a potential medical problem. Reaching to tactile targets on the body, however, is a complex perceptual motor skill involving the coordination of tactile and proprioceptive information with action. To examine the development of this understudied skill, we conducted a longitudinal investigation of how infants localize tactile targets on the face.

Infants (N = 24; 10 female; starting ages 1-6 months) were tested in a manual localization task on average every three weeks. They remained enrolled until they reached to eight vibrating tactile targets placed - one by one - at the left/right mouth corners, chin, left/right ears, left/right temples, and center temple in one session (See Figure 1). We coded target laterality (left, right), contact effector (hand, arm, tongue, torso, chair), and direct reaching (whether they touched the face prior to target contact and on which side of the face such touches occurred). Acceptable to high inter-rater reliability was achieved (Cohen’s k = 0.69 – 1.00, mean = 0.85).

Data were analyzed using generalized estimating equations (GEE). Infants contacted targets with the hand versus other effectors increasingly more with age (Wald x2(1) = 41.46, p < .001; Figure 2). They also became more likely to reach directly to targets with the hand, as opposed to touching elsewhere on the face first (Wald x2(1) = 23.34, p < .001). Finally, both direct touches (192/203) and touches to the face prior to target contact (193/215) most often involved the ipsilateral hand (p’s < .001).

The results demonstrate that over the course of the first year, the hand increasingly becomes the preferred effector when reaching to tactile face targets, and that infants reach to these targets more directly with age. Additionally, reaching to the body is strongly lateralized. Over roughly 90% of the time, infants used the ipsilateral hand to reach to a face target. Interestingly, even when using effectors other than the hands, infants demonstrate knowledge about the mechanical properties of the body: Infants only tried to move effectors that could lead to physical contact of the target (e.g. bringing the head and shoulder together so that the ear contacts/rubs against the shoulder) versus ones where physical contact could not be achieved (e.g., attempting to bring the head and shoulder together so that the center temple would contact/rub against the shoulder). Collectively, these findings provide new information about how reaching to the face emerges during the first year. Discussion will center on what these findings reveal about understanding the self at a sensorimotor level and how these findings can be used to provide guidelines to parents and medical professionals regarding when infants first become capable of reaching to different areas of the face in response to a source of discomfort (e.g., tingling due to an ear infection).

Authors

• Lisa K Chinn, Tulane University
  Presenting Author

• Claire Frances Noonan, Tulane University
  Non-Presenting Author

• Jeffrey J. Lockman, Tulane University
  Non-Presenting Author