Related Experiment Video
Updated: May 6, 2026
Frame-by-Frame Video Analysis of Idiosyncratic Reach-to-Grasp Movements in Humans
Published on: January 15, 2018
Development of infant reaching behaviors: kinematic changes in touching and hitting
Rejane Vale Gonçalves1, Elyonara Mello Figueiredo, Camila Bretas Mourão
1Physical Therapy Department, Graduate Program in Rehabilitation Sciences, Universidade Federal de Minas Gerais, Brazil.
Insights
Infant reaching skills develop between 4 and 8 months, with distinct hand movements like touching and hitting emerging. Kinematic analysis reveals changes in movement patterns as infants reach for targets.
Area of Science:
- Developmental psychology
- Motor control
- Infant behavior
Background:
- Understanding infant motor development is crucial for identifying developmental milestones.
- Reaching is a fundamental motor skill that undergoes significant development in early infancy.
- Previous research has described general changes in reaching, but detailed kinematic analysis is less common.
Purpose of the Study:
- To investigate the developmental trajectory of reaching in typical infants aged 4 to 8 months.
- To describe the specific hand kinematic patterns associated with changes in reaching behaviors.
- To differentiate kinematic characteristics between 'touching' and 'hitting' actions.
Main Methods:
- Longitudinal study design with biweekly follow-ups.
- Observation of 13 typical infants interacting with a target.
- Analysis of reaching behaviors, specifically 'touching' and 'hitting'.
- Documentation of kinematic variables: movement units, straightness index, distance, peak velocity, and time to peak velocity.
Main Results:
- The frequency of both 'touching' and 'hitting' behaviors increased over the 4-8 month period.
- Significant changes in hand kinematics were observed as infants developed their reaching skills.
- The distance traveled by the hand was consistently greater during 'hitting' compared to 'touching' actions.
- Kinematic alterations were specific to the movement patterns infants employed for reaching.
Conclusions:
- Infant reaching is characterized by evolving kinematic patterns between 4 and 8 months.
- Distinct reaching behaviors ('touching' vs. 'hitting') exhibit different kinematic profiles.
- This study provides detailed kinematic insights into the development of goal-directed reaching in infants.
Abstract:
This longitudinal study investigated the development of reaching in typical infants, from age 4 to 8 months, and described the pattern of hand kinematics underlying changes in the characteristics of infants' actions while reaching for a target. Thirteen infants were followed biweekly. Two reaching behaviors emerged during the infants' free interactions with the target, touching and hitting. Changes over time were documented for the number of movement units, straightness index, distance, peak velocity and time to peak velocity of the hand for touches and hits. We observed increases in the numbers of touches and hits and changes in hand kinematics over time; the distance traveled by the hand was greater for hitting compared to touching. These kinematic changes were specific to the movement patterns that infants adopted to reach to the target.
