Children's performance in mental rotation tasks: orientation-free features flatten the slope.

Studies of the development of mental rotation have yielded conflicting results, apparently because different mental rotation tasks draw on different cognitive abilities. Children may compare two stimuli at different orientations without mental rotation if the stimuli contain orientation-free features. Two groups of children (78 6-year-olds and 92 8-year-olds) participated in an experiment investigating development of the ability to mentally rotate and the ability to recognize and use orientation-free features. Children compared two stimuli, one upright and one rotated, and responded as quickly as possible indicating whether the stimuli were the same or different. The stimuli were either two panda bears or two ice-cream cones with three scoops of ice-cream of different colors. The panda bears were either identical or mirror images. The cones were either identical, mirror images, or non-mirror images. Response times increased linearly as a function of the angle of orientation when stimuli were the same and when the stimuli were mirror images. But response times were much less dependent on angle of orientation for non-mirror image stimuli. Children as young as 6 years recognized orientation-free stimulus features and responded without mentally rotating when the task permitted this strategy.