Ivanenko, Y. P., Dominici, N., Cappellini, G., Dan, B., Cheron, G. and Lacquaniti, F. (2004). Development of pendulum mechanism and kinematic coordination from the first unsupported steps in toddlers. J. Exp. Biol.207, 3797-3810.

In the on-line version of this paper, an error appears in equation 6(p. 3800). The correct version of the equation is as follows:
\[\ R_{{\alpha}{\beta}}({\Delta})=\frac{{{\int}}{\alpha}(t){\cdot}{\beta}(t+{\Delta})\mathrm{d}t}{\sqrt{{{\int}}{\alpha}^{2}(t)\mathrm{d}t{\cdot}{{\int}}{\beta}^{2}(t)\mathrm{d}t}},\]
In addition, in the on-line version, the first sentence of the second paragraph of the subsection `Relation with speed' in the Results(p. 3805) should read:

Fig. 5A shows the R vs Fr function for our toddlers at the first unsupported steps, 1–5 months later, for children older than 2 years of age, and for adults.

The print version of the article is correct.

We apologise to authors and readers for any inconvenience these errors may have caused.