Unidirectional interference in use of nondominant hand during concurrent Grooved Pegboard and random number generation tasks.

Summary The interference effect between Grooved Pegboard task with either hand and the executive task of cued verbal random number generation was investigated. 24 normal right-handed subjects performed each task under separate (single-task) and concurrent (dual-task) conditions. Articulatory suppression was required as an additional secondary task during pegboard performance. Analysis indicated an unambiguous distinction between the two hands. Comparisons of single-task and dual-task conditions showed an asymmetrical pattern of unidirectional interference with no practice effects during pegboard performance. Concurrent performance with non-dominant hand but not the dominant hand of random number generation performance became continuously slower. There was no effect of divided attention on peg-board performance. Findings support the idea that the nondominant hand on the peg-board and random number tasks draw from the same processing resources but that for the executive aspect random number generation is mo...