Tactual laterality effects and the processing of spatial characteristics: dichaptic exploration of forms by first and...

Tactual laterality effects (T.L.E.) were examined in first- and second-grade children when performing a dichaptic task. Our procedure, a modified version of Witelson's standard dichaptic task, emphasized the type of errors made, so that we could construct a weighted index (W.I.) for scoring rather than a strictly dichotomous one. The same data were compared using the two types of scoring indexes stated above. T.L.E. occurred consistently with the W.I. scores only, both in two independent groups or in the same group at a year's interval, suggesting (1) that a strictly dichotomous index might lead to loss of information, (2) that the results are reliable at least at the group level. Results are discussed in terms of possible applications of such a procedure to investigating the relationship between performance (spatial processing) and brain organization (hemispheric balance).