Perception of visually masked stimuli by individuals with aphasia: A methodological assessment and preliminary theoretical implications.

BACKGROUND: Studies of the automatic processes supporting language processing and dysfunction in aphasia often rely on priming paradigms. The ability to confidently interpret these studies in terms of understanding the relative contributions of automatic vs. controlled processing, however, depends on the ability to isolate only automatic processes. One way this may be accomplished is through the use of visual masking. The effective use of visual masking, however, depends on verification that there was no task-relevant information consciously available from the prime item. AIMS: The study reported here was designed to assess the visibility of visually masked stimuli, for both typical adults and adults with aphasia. METHODS #ENTITYSTARTX00026; PROCEDURES: This experiment involved 31 typical adults and 21 individuals with aphasia. Visual masking sequences were presented on a computer screen, with 11 different interstimulus intervals assessed. Participants made lexical decisions on the masked stimuli. The two participant groups were compared in terms of their ability to distinguish the word/non-word status of masked stimuli at the various intervals. OUTCOMES #ENTITYSTARTX00026;
RESULTS: Participants with aphasia showed an overall poorer ability to discriminate between visually masked words and non-words than typical adults.
CONCLUSIONS: The visual masking sequence effectively interfered with task-relevant conscious perception of some masked stimuli for typical adults and all masked stimuli for participants with aphasia. This finding, combined with preliminary data collected on a similar task that involved a simple presence/absence judgment on masked items, suggests that there may be differences in the ability of individuals with aphasia to process rapidly presented masked stimuli, even when there is minimal linguistic processing required.