Familial handedness and its relation to spatial ability following strategy instructions

This study compared subjects from right-handed families with subjects from nonrighthanded families in their ability to solve a mental-rotation task when instructed to use one of two different spatial strategies. All subjects completed a pretest Vandenberg. Next, one of the following procedures was presented prior to administering the Vandenberg posttest: Group 1 was given mental-rotation instructions, Group 2 was given spatial-orientation instructions, and Group 3 (control group) was given no special directions. For familial right-handers, no condition effects were found. In contrast, familial nonright-handers benefited significantly from mental-rotation instructions when compared both to their own control group and to familial right-handed subjects given the same instructions. However, with orientation instructions, the familial nonright-handers showed significantly less posttest improventnt than their control group. These results suggests familial non-rright-handers may be stronger in ability to use one spatial strategy, transformation of mental images, and weaker on a second, reorientation in relation to left-right cues. The educational and research implications of these findings are discussed.