Customarily, it is taught that strabismus acquired in childhood results in suppression of the diplopic image, whereas strabismus acquired in adulthood causes diplopia or conscious image ignoring, but not true cortical suppression. The pattern visual evoked potential (PVEP) was recorded from strabismic patients, three with childhood onset, two adult onset with diplopia, and three with longstanding adult onset strabismus "ignored" diplopia. Patients with childhood onset and adult onset "ignored" diplopia similarly showed essentially no response under haploscopic stimulation, whereas patients with diplopia and normal control subjects showed a 50% decrease (rivalry). These results suggest that adults with acquired strabismus who "ignore" the diplopic image actually have a suppressed cortical visual activity, as evidenced by the pattern visual evoked potential.