Overt and covert processing of left-side information in unilateral neglect investigated with chimeric drawings.

Overt and covert processing of contralesional information was investigated in 6 right-brain-damaged (RBD) patients with or without left hemispatial neglect by using three bedside tests that require the analysis of whole, half, and chimeric drawings. In the first task, patients named these stimuli. In the second task, patients designated as "same" or "different" drawings in a pair where one drawing was always whole and the other could be whole, half, or chimeric. In the third task, patients pointed to the more veridical, complete drawing that was presented with one half drawing, and two chimeric drawings. Although patients with no neglect performed without error in all conditions, patients with severe neglect based their performance on the analysis of the right side of the stimuli. In patients with mild neglect, not only did performance rely upon the right side of stimuli but it was also modulated by left-side information acquired either overtly or unconsciously.