On the other hand: Overflow movements of infants' hands and legs during unimanual object exploration

Kasey C. Soska, Margaret A. Galeon, Karen E. Adolph

Research output: Contribution to journalArticlepeer-review


Motor overflow is extraneous movement in a limb not involved in a motor action. Typically, overflow is observed in people with neurological impairments and in healthy children and adults during strenuous and attention-demanding tasks. In the current study, we found that young infants produce vast amounts of motor overflow, corroborating claims of symmetry being the default state of the motor system. While manipulating an object with one hand, all 27 of the typically developing 4.5- to 7.5-month-old infants who we observed displayed overflow movements of the free hand (on 4/5 of unimanual actions). Mirror-image movements of the hands occurred on 1/8 of unimanual actions, and the hands and legs moved in synchrony on 1/3 of unimanual acts. Motor overflow was less frequent when infants were in a sitting posture and when infants watched their acting hand, suggesting that upright posture and visual examination may help to alleviate overflow and break obligatory symmetry in healthy infants.

Original languageEnglish (US)
Pages (from-to)372-382
Number of pages11
JournalDevelopmental Psychobiology
Issue number4
StatePublished - May 2012


  • Infants
  • Motor overflow
  • Object manipulation
  • Posture
  • Symmetry

ASJC Scopus subject areas

  • Developmental and Educational Psychology
  • Developmental Neuroscience
  • Developmental Biology
  • Behavioral Neuroscience


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