An unexpected interactive pattern of visual field asymmetries revealed by faster/slower response partitioning.

Subjects were presented with unilaterally-exposed schematic, outline faces in one condition, and three-letter single-syllable first names in another. In either case there was an ensemble of four items which were to be partitioned, by the subjects making a manual choice-reaction-time response, into two subsets. No easy rule permitted the partitioning either of the faces or of the names (DEN, LES versus LEN, DES). While no clear pattern of asymmetries emerged from an overall analysis, or from a simple comparison of the two types of response, when the subjects' individual responses were instead partitioned into faster and slower, a striking pattern of interactive asymmetries emerged which was consistent for both sexes and both tasks. Thus the slower of the two responses was associated with a left field superiority, and the faster with a right. These findings were discussed in the context of perceived or covert task demands, which are not always immediately recognizable from a superficial or conventional analysis of response data, and the effect of positive (target) and negative (nontarget) processing upon behavioral asymmetries.