Your subconscious is smarter than you might think

A recent experiment by a team from Israel scores points against this position. Ran Hassin and colleagues used a neat visual trick called Continuous Flash Suppression to put information into participants’ minds without them becoming consciously aware of it. It might sound painful, but in reality it’s actually quite simple. The technique takes advantage of the fact that we have two eyes and our brain usually attempts to fuse the two resulting images into a single coherent view of the world. Continuous Flash Suppression uses light-bending glasses to show people different images in each eye. One eye gets a rapid succession of brightly coloured squares which are so distracting that when genuine information is presented to the other eye, the person is not immediately consciously aware of it. In fact, it can take several seconds for something that is in theory perfectly visible to reach awareness (unless you close one eye to cut out the flashing squares, then you can see the 'suppressed' image immediately).

Hassin’s key experiment involved presenting arithmetic questions unconsciously. The questions would be things like "9 - 3 - 4 = " and they would be followed by the presentation, fully visible, of a target number that the participants were asked to read aloud as quickly as possible. The target number could either be the right answer to the arithmetic question (so, in this case, "2") or a wrong answer (for instance, "1"). The amazing result is that participants were significantly quicker to read the target number if it was the right answer rather than a wrong one. This shows that the equation had been processed and solved by their minds – even though they had no conscious awareness of it – meaning they were primed to read the right answer quicker than the wrong one.

The result suggests that the unconscious mind has more sophisticated capacities than many have thought. Unlike other tests of non-conscious processing, this wasn’t an automatic response to a stimulus – it required a precise answer following the rules of arithmetic, which you might have assumed would only come with deliberation. The report calls the technique used "a game changer in the study of the unconscious", arguing that "unconscious processes can perform every fundamental, basic-level function that conscious processes can perform".

These are strong claims, and the authors acknowledge that there is much work to do as we start to explore the power and reach of our unconscious minds. Like icebergs, most of the operation of our minds remains out of sight. Experiments like this give a glimpse below the surface.

Tom Stafford