6.3 Studying consciousness in the laboratory

A complete explanation of consciousness is still far out of our reach. But using our current knowledge, we may be able to discern experimentally between these and other theories.

For example, a key difference between these two theories is the expected focus of brain activity for different conscious experiences. This can be studied by exposing someone to stimuli which are above and below the limits of conscious perception, such as an image of a word. When consciously perceived, there is a burst of activity across different brain regions, but when detected only subconsciously, the brain activity is much more limited.

Figure 19 A ‘signature of consciousness’ – patterns of brain activity recorded as a response to conscious (left) and non-conscious (right) visual stimuli (Dehaene and Changeux, 2011)

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This is a diagram showing two human brains within outline heads. Regions of recorded brain activity are coloured. The left is labelled ‘Visible word’, and there are seven patches of green seen across the brain where there is brain activity. The right is labelled ‘Invisible word’, and there are two small patches of red where there is brain activity. The larger of these is located near the base of the brain at the back and the second particularly small patch is near the centre of the brain. These both have a similar shape and location although smaller size to corresponding patches in the left brain.

Figure 19 A ‘signature of consciousness’ – patterns of brain activity recorded as a response to conscious (left) and non-conscious ...

A complete explanation of consciousness will depend on continuing experimental investigation and technological advances, in parallel with further theoretical developments.