Recent years three attentional networks have been defined in anatomical and functional terms. Understanding the efficiency of these networks in normal subjects helps to better evaluate abnormalities arising in cases of brain injury, stroke, schizophrenia, and attention deficit disorder. Moreover, the development of methods to improve attention in normals and to rehabilitate patients requires convenient assays of changes in the efficiency following training. We have developed an experimental test of half an hour that provides a measure of the efficiency of the attentional networks involved in alerting, orienting and executive attention. Our paradigm is designed to be used with children, adults, patients and non-human primates since it does not require language. Efficiency of the alerting network is examined by changes in RT resulting from a warning signal. Efficiency of orienting is examined by changes in RT that accompany cues indicating where the target will occur. The efficiency of the executive network is examined by requiring the subject to respond by pressing two keys indicating the direction (left or right) of a central arrow surrounded by congruent, incongruent or neutral flankers. We have run 40 adult subjects in two blocks of 288 trials each. Mean scores (and SD) for each network are: alerting 47 (18) ms, orienting 51 (21) ms, executive 84 (25) ms. Moderate to high reliabilities were found for all networks. Under our conditions the three networks are independent by ANOVA and scores are uncorrelated across subjects.