Direct vs. indirect tests of the information available from masked displays: what visual masking does and does not prevent.

Abstract

A comparison was made between two procedures for testing whether an alpha-numeric character, which was patter masked to prevent awareness, could access higher-order information concerning its category. In the indirect test, subjects made categorization responses to a letter or digit target which was immediately preceded by a masked letter or digit stimulus. In the direct test, the target stimulus was not presented; nevertheless, categorization responses were required, and it was assumed that any higher-order information available from the masked stimulus would be evident in these responses. Using the indirect procedure, category information was shown to be accessed by the masked stimulus, since target discrimination was affected by the category relationship between the stimuli. In contrast, categorization responses when the target was absent (in the direct test) were uninfluenced by the category of the masked stimulus. It was suggested that pattern masking disrupts the information necessary for (direct) report. However, it does not prevent the processing of stimuli to semantic levels, or the (indirect) effect the information accessed on the analysis of subsequent stimuli.