Table 1: Comparison between observed motor development items in a sample of “high-potential” children followed longitudinally () (Vaivre-Douret) [5] and French developmental standardised norms in the first two years of life [8, 9].
 Items observed (Vaivre-Douret) [5] Sample ( 𝑛 = 6 0 ) mean age and SD*(months, weeks) DEF-MOT norms (Vaivre-Douret) [8] mean age and SD (months, weeks, days) Brunet-Lézine norms revised [9] success 50%–90% (months) Holds head in axis 1 m + 1 w 2 m 4 d + 1 m 1 d 3 m Voluntary grasp 3 m + 1 w 4 m 10 d + 1 m 2 d 4 m Turning overresponse 4 m + 4 w 6 m 10 d + 1 m 9 d 8 m Sitting without support 6 m + 3 w 8 m 6 d + 1 m 2 d 10 m Sits up alone 7 m + 3 w 8 m 24 d + 1 m 6 d 10 m Stands up with support 8 m + 4 w 10 m 18 d + 1 m 18 d 10 m Crawls 8 m + 3 w 10 m 12 d + 1 m 3 d 9 m Takes bead between thumbs and forefinger 8 m + 2 w 9 m 10 d + 1 m 6 d 9 m Independent walking 12 m + 4 w 14 m 20 d + 2 m 6 d 14 m Start eating with a spoonon his own 12 m + 2 w 18 m 14 d + 1 m 2 d 17 m Climbs stairs 15 m + 2 w 17 m 4 d + 1 m 10 d — Comes down stairs withhelp without alternating feet 16 m + 3 w 19 m 1 d + 1 m 2 d — Tower of at least 8 bricks 23 m + 4 w 29 m 1 d + 1 m 2 d 30 m Climbs stairs alone without support alternating feet 24 m + 1 w 34 m 1 d + 2 m 1 d — Puts slippers on without help 24 m + 3 w 30 m 8 d + 1 m 5 d 30 m Rides tricycle or bikewith stabilisers 24 m + 3 w 36 m 3 d + 1 m 1 d —
*(Significant items (Student’s -test, liberty degree = 118), , compared to motor development standardised norms).