Understanding Why Many Choose the Left Arm to Rock a Baby
Researchers from the Norwegian University of Science and Technology explored a simple, everyday action: rocking a baby. The study, published in Infancy, examined how caregivers instinctively hold infants during soothing routines. A total of 765 participants took part, and across the group, a striking 75 percent preferred to rock with the non-dominant hand. This pattern emerged regardless of whether the participants had full strength or practiced caregiving regularly [Infancy].
Two main explanations have been proposed to explain this behavior. The first theory suggests rocking on the left side helps a parent hear the baby’s heartbeat more clearly, which in turn promotes calmness. A related idea is that the left position may allow quicker assessment of the infant’s emotional cues, since people often process auditory and emotional signals through the left ear and surrounding neural pathways [Infancy].
The second theory emphasizes practical multitasking. By keeping the dominant hand free, a caregiver can attend to another task while still comforting the child, explaining why the pattern appears even when the left arm is simply more convenient in the moment [Infancy].
As babies grow and their weight increases, the tendency shifts. Parents and caregivers often switch to cradling or carrying the child with the stronger, dominant arm to maintain control and stability during longer periods of holding. The balance between soothing and practicality reflects a natural adjustment as the child develops and mobility changes the caregiver’s approach [Infancy].
Alongside these observations, reflections on caregiving practices show how cultural norms and everyday routines shape what feels most comfortable. The instinct to choose a particular side for soothing can be influenced by handedness, spatial awareness, and the immediate needs of both the infant and the caregiver. In practical terms, caregivers may experiment with different positions to determine what most effectively calms the child in a given moment, while remaining mindful of safety and support. The findings underscore how even routine actions reveal a blend of biology, habit, and responsive care [Infancy].
Note: historical or incidental mentions connected to unrelated topics should be understood as separate from the main discussion of infant soothing techniques and caregiver behavior. The focus here remains on the documented patterns of arm preference during rocking and the plausible reasons behind them, rooted in early research and observed caregiving dynamics [Infancy].