Editing Handedness (section)

== Developmental timeline ==
{{Anchor|Handedness developmental timeline}}Researchers studied fetuses in utero and determined that handedness in the womb was a very accurate predictor of handedness after birth.<ref>{{cite journal | vauthors = Hepper PG, Wells DL, Lynch C | s2cid = 805957 | title = Prenatal thumb sucking is related to postnatal handedness | journal = Neuropsychologia | volume = 43 | issue = 3 | pages = 313–5 | year = 2005 | pmid = 15707608 | doi = 10.1016/j.neuropsychologia.2004.08.009 }}</ref> In a 2013 study, 39% of infants (6 to 14 months) and 97% of toddlers (18 to 24 months) demonstrated a hand preference.<ref>{{cite journal | vauthors = Nelson EL, Campbell JM, Michel GF | title = Unimanual to bimanual: tracking the development of handedness from 6 to 24 months | journal = Infant Behavior & Development | volume = 36 | issue = 2 | pages = 181–8 | date = April 2013 | pmid = 23454419 | pmc = 3615031 | doi = 10.1016/j.infbeh.2013.01.009 }}</ref>

Infants have been observed to fluctuate heavily when choosing a hand to lead in grasping and object manipulation tasks, especially in one- versus two-handed grasping. Between 36 and 48 months, there is a significant decline in variability between handedness in one-handed grasping; it can be seen earlier in two-handed manipulation. Children of 18–36 months showed more hand preference when performing bi-manipulation tasks than with simple grasping.<ref name=":0">{{Cite journal|last1=Fagard|first1=Jacqueline|last2=Lockman|first2=Jeffrey J. | name-list-style = vanc |title=The effect of task constraints on infants' (bi)manual strategy for grasping and exploring objects|journal=Infant Behavior and Development |volume=28|issue=3|pages=305–315 |doi=10.1016/j.infbeh.2005.05.005|year=2005}}</ref>

The decrease in handedness variability in children of 36–48 months may be attributable to preschool or kindergarten attendance due to increased single-hand activities such as writing and coloring.<ref name=":0" /> Scharoun and Bryden noted that right-handed preference increases with age up to the teenage years.<ref name=":1" />