Rengachary J, d'Avossa G, Sapir A, Shulman GL, Corbetta M. Is the Posner Reaction Time Test more accurate than clinical tests in detecting left neglect in acute and chronic stroke? Objective To compare the accuracy of common clinical tests for left neglect with that of a computerized reaction time Posner test in a stroke population. Design Neglect measures were collected longitudinally in patients with stroke at the acute (≈2wk) and chronic (≈9mo) stages. Identical measures were collected in a healthy control group. Setting Inpatient and outpatient rehabilitation. Participants Patients with acute stroke (n=59) with left neglect, 30 of whom were tested longitudinally; healthy age-matched controls (n=30). Interventions Not applicable. Main Outcome Measures A receiver operating characteristic analysis ranking the measures' sensitivity and specificity using a single summary statistic. Results Most clinical tests were adequately accurate at the acute stage, but many were near chance at the chronic stage. The Posner test was the most sensitive test at both stages. The most sensitive variable was the reaction time difference for detecting targets appearing on the left compared with the right side. Conclusions Computerized reaction time tests can be used to screen for subtle but potentially clinically relevant left neglect, which may not be detectable by conventional clinical tests, especially at the chronic stage. Such tests may be useful to assess the severity of the patients' deficits and provide more accurate measures of the degree of recovery in clinical trials than established clinical measures.