This study explores the possibility that attentional deficits are an early clinical symptom of Alzheimer's disease. The three goals are to demonstrate that individuals with Alzheimer's disease are impaired on tasks of attentional processing, to compare the sensitivity of currently used measures of attention to attentional dysfunction, and to compare the behavioral response styles (errors of commission) of Alzheimer's disease subjects and non-impaired subjects. The subjects were 22 males and 46 females with a mean age of 70.76 years. Thirty-six had the presumptive diagnosis of Alzheimer's disease; 18 were identified as mildly impaired and 18 as moderately impaired on the Cognitive Capacity Screening Examination. The remaining 32 subjects comprised the non-impaired control group. Five measures of attention were administered to all participants: the Digit Span Subtest of the WAIS-R, the Seashore Rhythm Test of the Halstead-Reitan Neuropsychological Battery, the Vigilance and Distractibility tasks of the Gordon Diagnostic System, and the Concentration/Interference task. The results show a significant difference in attentional processing between normal (non-impaired) subjects and subjects diagnosed with Alzheimer's disease. All measures of attention used in this study, except the Concentration/Interference task, differentiated normal subjects from moderately impaired Alzheimer's disease subjects. The Digit Span Subtest and the Seashore Rhythm …