The tadpole does not only appear in ponds, but pops up in many of the drawings that children do between the ages of two and five (see illustration, top right).
Some children continue drawing tadpole figures for more than a year whereas others may draw only two or three over as many days.
But by the time children start school, most can produce more elaborate figures. Some stop off at a transitional stage (top right) in which the arms and any items associated with the torso are placed lower down the figure. Most, however, go straight on to a more conventional figure (middle row, right) which has an enclosed shape for the torso and arms either side.
The subsequent development pattern is equally well-established: as children grow older, they put more details into their figures. The proportions also become more realistic, especially the head, the size of which is often greatly exaggerated by the very young.
But this seemingly universal progress is actually less inevitable and culture-free than it seems.
As Dr Maureen Cox points out in the current issue of the Journal of Art and Design Education, there have been startling changes to this pattern even in western societies.
Two-eyed profiles were very common in Western Europe and North America during the late-19th and early-20th centuries. But they have since virtually disappeared from children's drawings.
"What appeared to be, at one time, an inevitable psychological 'stage' in children's drawing development was a particular style which was copied by the children from their older classmates or siblings, and which, for whatever reason, then fell out of favour and was discontinued," says Dr Cox, senior lecturer in psychology at the University of York.
"We should be careful of assuming, therefore, that a particular feature of children's drawings reflects their 'natural' and inevitable psychological development; it may be that they are copying in a more or less direct way the kinds of pictures they have available to them."
Dr Cox also says that the human figure assumes less importance in the drawings of children from some other cultures. Researchers studying the drawings of Samburu children in Kenya found that, given a free choice, only about 25 per cent of them drew people. Cattle were much more important.
And drawings of classrooms by children in Tanzania and Sweden also highlighted some important cultural differences. The African children depicted themselves and their classmates as very small in comparison with their teacher. In contrast, the Scandinavian pictures showed more intimate groups in which the pupil was nearly as large as the teacher.
Comparisons of drawings done by children in the UK and the Middle East have identified more subtle differences. For example, young British children usually draw the torso as a roughly rounded, enclosed area, whereas Islamic societies seem to favour rectangular torsos.
However, Dr Cox says the distinctiveness of children's drawings in different parts of the globe is being reduced by mass communications.
In Papua New Guinea, where there is no tradition of representational artwork, children who attend school are beginning to produce western-style drawings.
However, it is not inevitable that western images will predominate, she says. In the western desert of Australia, where Aboriginal art is highly regarded, Warlpiri children are using both the local and western styles of drawings, sometimes in the same picture.
"Drawings of people by Australian Aboriginal children", by Dr Maureen V Cox, the Journal of Art and Design Education, Vol. 17, No. 1, published by Blackwell, 108 Cowley Road, Oxford, OX4 1JF. Dr Cox can be contacted at the Department of Psychology, University of York, Heslington, York YO1 5DD.