Mental rotation of unfamiliar stimuli by teenagers with mental retardation: role of feature salience.

Teenagers with mental retardation and two groups of children without mental retardation matched on MA or CA carried out mental rotation tasks of unfamiliar stimuli. Three shapes composed of four arms were used. For each shape, there was a version with a salient feature (F+), and a version with no salient feature (F-). Results showed that teenagers with mental retardation could perform mental rotation tasks with unfamiliar stimuli. However, they had a steeper increase in error rate for F- stimuli than did the MA and CA groups. Individuals with mental retardation may have difficulties in performing mental rotation tasks when stimuli have no feature with a salient axis of elongation.