Mirror reading in right and left handers: are sinistrals really superior?

While left handers, where they do in fact appear to differ from right handers in cognitive function, have generally been found to be slightly inferior on verbal tasks, there are some reports of a sinistral superiority for nonverbal or spatial abilities. Tankle and Heilman (Brain and Language, 1982, 17, 124-132) report a sinistral superiority in (obligatory) reading of left-right mirror-reversed text. However, in an investigation which included various other forms of geometrical transformation of the written word, we find that strong familial sinistrals are either not different from or even slightly inferior to dextrals in reading most transformations, including left-right mirror reversals.