Phinney J S, Nummedal S G
Percept Mot Skills. 1979 Feb;48(1):223-7. doi: 10.2466/pms.1979.48.1.223.
50 boys and 50 girls, from Grades K through 4, were presented with 180 degrees perspective-taking tasks that varied arrays in terms of the number of front-back and left-right orientation reversals and left-right position reversals. Results confirmed existing evidence that left-right orientation reversals are more difficult than front-back orientation reversals in arrays of one object. However, with arrays of two objects, left-right orientation reversals appear easier than front-back orientation reversals, apparently because of the relationship between the objects.