Aware and unaware perception in hemispatial neglect: evidence from a stem completion priming task.

The current study used the process dissociation procedure in conjunction with a stem-completion priming task to disentangle the influences of aware and unaware perception in patients with hemispatial neglect. One lateralized picture prime was presented simultaneously with a filler picture followed by a centrally presented word stem. In the inclusion condition participants were asked to complete the word stem with the previously presented picture name; in the exclusion task they were asked to complete the stem with the name of a picture other than the one previously presented. Findings indicated that neglect patients had reduced unaware perception of pictures presented in the left visual field and an absence of awareness for those same pictures. In addition, patients had reduced awareness for right visual field pictures, but unaware perception remained intact. These findings suggest that observations of preserved information processing in neglect are due to residual unaware perception and not due to residual awareness of information in the neglected hemispace.