Does not knowing where a hidden number will appear change how your brain processes it?

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Previous research suggested that selective spatial attention determines unconscious processing under continuous flash suppression (CFS). Specifically, Eo et al. (2016) suggested that not attending to a stimulus’s location facilitates unconscious processing by reducing the depth of CFS. This study used an experimental number-priming paradigm to further test that modulation-by-attention model.

Participants (N = 26) compared a visible target number with five. Prime-target pairs were either congruent—both numbers smaller than five or both larger than five—or incongruent. The researchers varied spatial attention toward the primes by manipulating uncertainty about where they would appear.

The model predicted faster reaction times (RTs) for congruent than incongruent pairs when the prime’s location was uncertain. When its location was certain, the researchers predicted no RT difference between congruent and incongruent pairs.

The data were analyzed using sequential Bayes factors (BFs). There was no effect of location uncertainty on unconscious priming under CFS (BF0+ = 5.16). However, even visible primes had only a weak influence on RTs.

The authors discuss possible reasons for the lack of robust number-priming effects. Based on exploratory analyses, they conclude that the numerical order of the prime and target created a response conflict that interfered with the predicted priming effect.