Implicit associative priming in a patient with left visual neglect.

Recent studies have suggested that patients with visual neglect may process, even if without awareness, perceptual features of the neglected stimuli. The aim of the current study was to further investigate whether the ignored stimuli are processed at a deeper level. Findings from a patient with damage to the right hemisphere and with left visual neglect (no hemianopia) are reported. He showed an associative priming in the neglected space: response to a word in the right visual field was faster when the word was preceded by the brief presentation of an associated word in the neglected field. When obliged to orient attention to the left side of a computer screen, he was not able to detect the presence of, to read aloud, or to judge the lexical status and semantic content of left-sided stimuli. This patient was able to perform a covert post-perceptual processing of the neglected stimuli, but could not do so when explicitly requested.