In recent research, two qualitatively different classes of mental operations have been identified. The performance of one type of cognitive task requires attention, in the sense of mental effort, for its execution, while the second type can be performed automatically, independent of attentional control. Further research has shown that automatic…

Tested the hypothesis that young children's tendency to draw horizontal or vertical objects perpendicularly to an oblique surface reflects their preference for perpendicular drawings as conceptually correct depictions. (Author/RH)