Abstract

The Bicycle Drawing Test (bdt) is a measure of mechanical reasoning and visual-spatial and graphic functions. An adequate validation of the coding criteria of this test is still lacking. Aims of this work are: 1. to check the reliability of the scales by Greenberg, Rodriguez e Sesta (1994); 2. to explore other possible dimensions; 3. to compare the drawing and the copying task, in order to study the cognitive processes involved in each mode of execution. bdt (drawing and copying) was administered to 326 children from 7 to 10 years old. None of the categories proposed by Greenberg, Rodriguez e Sesta (1994) reached a sufficient Cronbach's α. With item analyses and explorative factor analyses we found three dimensions: Mechanical Reasoning (mr), Fine Pictorial Skill (fps), Spatial Organization (so). Separate ancovas were used to compare mr and so by sex and age, including a covariate: an index of visual-motor control, i.e. the sum of the only five items in which the scores were higher in the drawing than in the copy (belonging all to the fps scale). In sum, our preliminary analyses showed that some items of the Greenberg's coding are not discriminative, and the remaining items have a different dimensionality. Our subsequent analyses showed that the bdt can measure efficiently mechanical reasoning and spatial organization, without significant interference of visual-motor control.