Table 1: Comparison between observed motor development items in a sample of “high-potential” children followed longitudinally ( 𝑛 = 6 0 ) (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 axis1 m + 1 w2 m 4 d + 1 m 1 d3 m
Voluntary grasp3 m + 1 w4 m 10 d + 1 m 2 d4 m
Turning overresponse4 m + 4 w6 m 10 d + 1 m 9 d8 m
Sitting without support6 m + 3 w8 m 6 d + 1 m 2 d10 m
Sits up alone7 m + 3 w8 m 24 d + 1 m 6 d10 m
Stands up with support8 m + 4 w10 m 18 d + 1 m 18 d10 m
Crawls 8 m + 3 w10 m 12 d + 1 m 3 d9 m
Takes bead between thumbs and forefinger8 m + 2 w9 m 10 d + 1 m 6 d9 m
Independent walking12 m + 4 w14 m 20 d + 2 m 6 d14 m
Start eating with a spoonon his own12 m + 2 w18 m 14 d + 1 m 2 d17 m
Climbs stairs15 m + 2 w17 m 4 d + 1 m 10 d
Comes down stairs withhelp without alternating feet 16 m + 3 w19 m 1 d + 1 m 2 d
Tower of at least 8 bricks23 m + 4 w 29 m 1 d + 1 m 2 d30 m
Climbs stairs alone without support alternating feet24 m + 1 w34 m 1 d + 2 m 1 d
Puts slippers on without help24 m + 3 w30 m 8 d + 1 m 5 d30 m
Rides tricycle or bikewith stabilisers24 m + 3 w 36 m 3 d + 1 m 1 d

*(Significant items (Student’s 𝑡 -test, liberty degree = 118), 𝑃 < 0 . 0 0 1 , compared to motor development standardised norms).