The results constitute a challenge to existing theories of unconscious processes that maintain that reading and solving maths problems – two prime examples of complex, rule-based operations – require consciousness.
To present sentences and equations unconsciously, the researchers used a cutting-edge technique called Continuous Flash Suppression (CFS). In CFS, one eye is exposed to a series of rapidly changing images, while the other is simultaneously exposed to a constant image. The rapid changes in the one eye dominate consciousness, so that the image presented to the other eye is not experienced consciously. Using this technique, more than 270 students at the Hebrew University were exposed to sentences and arithmetic problems.
In one set of experiments using this technique, participants were asked to pronounce numbers that appeared on a computer screen. These numbers were preceded with unconscious arithmetic equations. The results of the experiments showed that participants could more quickly pronounce the conscious number if it had been the result of the unconscious equation. For example, when 9-5-1 was shown non-consciously, the participants were faster in pronouncing 3 than 4, even though they did not consciously see the equation.
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