A new study has thrown light on the role the brain plays when drawing a cartoon face from memory. Researchers say that the brain remembers key locations and literally "joins the dots" using a straight or curved line, thus achieving the desired image on paper.
The study led by Miall, Gowen and Tchalenko has revealed that the captured visual information is stored as a series of locations or action plans to reach those locations.
During the study, participants who had no particular expertise as artists were studied using an MRI scanner to measure levels of oxygen in the brain.
They viewed black and white cartoons of faces, and were asked to reproduce them using pencil and paper.
The findings showed that looking at the cartoons activated visual processing areas of the brain, which are responsive to faces, especially if the cartoon was displayed at the same time as they produced the drawing.
However, there was no maintained activity in those areas when the subjects had to wait before drawing, which indicated that the memory of the cartoon face is transformed into a different, non-visual form.
In fact, the researchers noticed increased activity in parietal cortex and frontal areas consistent with the encoding and retention of the spatial information as an action plan, representing a series of targets for ocular fixation or as spatial targets for the drawing action.
The scientists conducted other experiments in which they precisely measured where people look as they perform these tasks.
And they discovered that facial information is captured during a sequence of eye movements towards certain features of the cartoons, and the information is stored as spatial locations for subsequent eye and hand actions.
The drawing process then recreates these spatial features as the eye and hand are guided by the retained action plans.
Based on their observations, the researchers came to the conclusion that brain imaging, in combination with eye and hand tracking, can dissect complex visually guided tasks into separate functional stages.
The study is an important step towards a full understanding of how sensory information is used to guide actions.
The study has been published in the journal Cortex.