No stable arm preference during the pre‐reaching period: A comparison of right and left hand kinematics with and without a toy present

Abstract

Adult hand preference emerges from complex developmental changes in arm and hand use during childhood. Recent reports have highlighted the importance of understanding arm and hand use during the first year of life including the period before reach onset. This longitudinal study tested the hypothesis that significant right-left differences exist in pre-reaching arm movements. We examined right and left hand kinematics from 13 healthy infants during trials with and without a toy present from 8 weeks of age through the week of reach onset. Significant right-left differences were found, however there was no clear pattern within a condition or across conditions. Without a toy present, the right hand moved faster, yet ended further from midline, and displayed more movements during the Late phase compared to other phases. With a toy present, the right hand moved longer lengths, yet ended movements further away from the toy. When left and right hand kinematics were combined, previous findings of right hand kinematics alone were supported. Although infants begin adapting their pre-reaching kinematics many weeks before reach onset, we did not find evidence of a systematic right--left difference before reach onset in movements with or without a toy present. Our results, coupled with other reports, suggest hand asymmetries begin to emerge over the year following reach onset amid developmental changes both within the infant, and the physical and social environment.

Perinatal stroke causes abnormal trajectory and laterality in reaching during early infancy

“…At 5 months of age infants reach equally with the right and left when a toy is presented at midline (Souza, de Azevedo Neto, Tudella, & Teixeira, 2012). From ages 6 to 12 months infants show unstable hand-use preference, meaning they do not show a consistent side of the body for reaching (Ferre, Babik, & Michel, 2010;Lynch, Lee, Bhat, & Galloway, 2008). As such, early stable hand preferences may signal a motor disability.…”

Longitudinal changes in muscle activity during infants' treadmill stepping

“…Kinematic analyses of these steps show quite clearly that significant changes occur over these 12 mo in infants' leg movement patterns and interlimb coordination (Groenen et al 2010;Thelen and Ulrich 1991;Vereijken and Thelen 1997), as is true of all other motor behaviors when assessed over such a wide developmental time frame in infancy (e.g., Adolph et al 1998;Freedland and Bertenthal 1994;Haehl et al 2000;Konczak and Dichgans 1997;Lynch et al 2008).…”

Moving What Is Seen: Arm Visibility Modulates Infants’ Manual Preference

“…As observed previously by the age of voluntary reaching onset (Lynch et al, 2008;Morange & Bloch, 1996;Ramsay, 1980;Rönnqvist & Domellöf, 2006;Seth, 1973;Souza et al, 2012), infants' handedness was found to be quite variable regarding both the selection of the right or the left hand and the consistency of that choice. Approximately half the infants showed either undefined or left hand preference.…”

“…That perceptual lateral bias has been proposed to be a potential factor inducing the predominant preference for the right hand to perform motor tasks in humans (Coryell & Michel, 1978;Michel, 1981;Michel & Harkins, 1986). Even though predominant side of head turning in the first months of life has been suggested to predict manual preference in older infants (Michel & Harkins, 1986), by the age of voluntary reaching onset manual preference is rather variable (Jacobsohn, Rodrigues, Vasconcelos, Corbetta, & Barreiros, 2014;Lynch, Lee, Bhat, & Galloway, 2008;Morange & Bloch, 1996;Ramsay, 1980;Rönnqvist & Domellöf, 2006;Seth, 1973;Souza, Azevedo Neto, Tudella, & Teixeira, 2012). Morange and Bloch (1996), for example, found predominance of left-handedness in 4-month-old infants, whereas Souza et al (2012) found approximately the same numbers of right-and left-handers in 5-month-olds.…”