Tachistoscopic visual perception after closed head injury.

Tachistoscopic visual perception was examined in 42 right-handed closed head injury patients and 10 normal controls by determining the duration for recognition of a trigram in central vision and by employing a visual field laterality task. Thresholds did not vary with severity of injury but were significantly longer than those of controls for midly, moderately, and severely injured patients. A nonsignificant right visual field superiority for trigram recognition was exhibited by all groups. Recognition of trigrams in either visual field was impaired in moderately and severely injured patients relative to controls. Possible explanations for these findings are discussed.