The same-different task as a tool to study unconscious processing

The function of consciousness has often been investigated by looking at the cognitive processes that can(not) be performed without conscious awareness. The most important processes – historically and theoretically - in this context are semantic processing and information integration. Here, I will argue that a subliminal priming version of the same-different task is a perfect tool to investigate these processes because it (i) allows a clear separation between the stimuli that are consciously processed and those that remain unconscious, and (ii) requires the unconsciously presented stimuli to be integrated. An overview of the work that has used the subliminal same-different task to target these processes is presented, and some suggestions for how the task could be used in future work are made. The potential of the subliminal same-different task to elaborate on the cognitive architecture needed to successfully perform a same-different task is also discussed.

The limits of unconscious semantic processing

Do supraliminal and subliminal priming capture different facets of words’ semantic representations? We used metaphorical priming between space and time as a test bed for this question. While people conceptualize time along the lateral and sagittal axes, only the latter mapping comes up in language (the future is in front of you, not to your right). We assessed facilitation on temporal target words by lateral (left, right) and sagittal (back, front) primes, in masked and overt conditions. Supraliminally, we observe similar sagittal and lateral priming, while the masked effect is stronger on the sagittal axis, and weak to non–existent on the lateral one. These results are observed in an original and a replication studies; and are strongly confirmed by a Bayesian meta–analysis of the two. We conclude that unconscious word processing is limited to linguistically–encoded information, while consciousness may be needed to fully activate semantic representations.