Size and Quality of Drawings Made by Adults Under Visual and Haptic Control.

The aim of this study was twofold. First, our objective was to test the influence of an object's actual size (size rank) on the drawn size of the depicted object. We tested the canonical size effect (i.e., drawing objects larger in the physical world as larger) in four drawing conditions - two perceptual conditions (blindfolded or sighted) crossed with two materials (paper or special foil for producing embossed drawings). Second, we investigated whether drawing quality (we analysed both the local and global criteria of quality) depends on drawing conditions. We predicted that drawing quality, unlike drawing size, would vary according to drawing conditions - namely, being higher when foil than paper was used for drawing production in the blindfolded condition. We tested these hypotheses with young adults who repeatedly drew eight different familiar objects (differentiated by size in the real world) in four drawing conditions. As expected, drawn size increased linearly with increasing size rank, whatever the drawing condition, thus replicating the canonical size effect and showing that this effect was not dependent on drawing conditions. In line with our hypothesis, in the blindfolded condition drawing quality was better when foil rather than paper was used, suggesting a benefit from haptic feedback on the trace produced. Besides, the quality of drawings produced was still higher in the sighted than the blindfolded condition. In conclusion, canonical size is present under different drawing conditions regardless of whether sight is involved or not, while perceptual control increases drawing quality in adults.