Abstract
Selective attention and orienting of attention have sometimes been used interchangeably in the literature. However, there is some evidence suggesting that the two mechanisms may implicate distinct areas of the brain. The distinction between selective- and orienting of- attention is important for both theoretical and clinical reasons since it has implications for the diagnosis and treatment of ADHD as well as of other clinical populations. A special paradigm was designed (for use in the scanner) in order to investigate whether these two aspects of attention are dependent or distinct. The paradigm is a combination of the cost-benefit technique (Posner, Snyder, & Davidson, 1980) with an exogenous cue (Jonides, 1981) and a conjunctive visual search task (Triesman & Gelade, 1980). This new paradigm enabled us to compare low vs. high selective attention conditions as well as valid vs. invalid trials within a single task. As was expected, the behavioral data showed significant main effects of selectivity and validity whereas there was no interaction between these factors. Moreover, imaging data showed that selective and orienting attention were mediated by two rather distinct fronto-parietal networks. Both functions activated the cingulate gyrus but at different foci. Orienting-related activation was evident in the inferior frontal gyrus and precentral gyrus. Selecting-related activation was found in the medial frontal gyrus and at some parietal regions in the left hemisphere. These results support the hypothesis that these are two independent functions as assumed by the four-facet model of attention (Tsal, Shalev & Mevorach, 2005). Since in some cases ADHD is characterized by weak selective attention and/or deficient orienting of attention the present findings may help in the future to shed light on the etiology of ADHD.