Crossing the midline by four to eight year old children.

In Experiment 1 children (Kinder, 4-5 yr; Prep, 5-6 yr; Grade 1, 6-7 yr; Grade 2, 7-8 yr) bisected horizontal lines placed to the left, right or across the midline. The youngest groups displayed symmetrical neglect, erring to the left with the left hand and to the right with the right, the adult pattern of leftwards error not appearing until about Grade 2. However, while Prep, Grade 1 and Grade 2 sinistrals showed bigger between-hand differences than dextrals, this was not, unlike an earlier study, true of the youngest Kinder group, and symmetrical neglect did not appear to be peculiar to young sinistrals. A timed peg-moving task in Experiment II showed that performance did not slow when crossing the midline; nor did young sinistrals perform better with centrifugal abductive movement. These and other findings were incompatible with the idea of callosal immaturity in young sinistrals.