Thinking is an afterthought

Here’s another potential nail for the coffin holding our cherished notion that humans choose our actions. Mathias Pessiglione and colleagues tested subliminal learning in humans: “Subliminal Instrumental Conditioning Demonstrated in the Human Brain.” They flashed a brief image, followed it with a masking image, and reinforced participants’ behavior differentially. So, the subliminal image came to serve as a discriminative stimulus for a given behavior (in this case, betting on poker hands).

A news reporter for Nature recounted the results this way:

The subjects won more than they lost, indicating that their brains recognized the unperceived symbols and learned to associate them with reward or punishment. Functional neuroimaging showed that the mechanism involves the ventral striatum, a brain area associated with assessing reward value.

We humans often simply are not conscious of the workings of our brains. Not only do we learn to perform routine tasks automatically, we even learn discriminations without thinking about them. As Pessiglione et al. describe it, “We provide evidence that instrumental learning can occur without conscious processing of contextual cues. This finding might relate to previous evidence for implicit or procedural learning, where behavioral responses can be adapted to the statistical structure of stimuli that fails to be reported explicitly.”

I suspect that we shall come to understand that a very large proportion of our behavior is performed without reference to our self-perceived thinking. Probably that thinking is just an epiphenomenon, a by-product, and afterthought, if you will.

Pessiglione, M., Petrovic, P., Daunizeau, J., Palminteri, S., Dolan, R. J., & Frith, C. D. (2008). Subliminal instrumental conditioning demonstrated in the human brain. Neuron 59, 561–567. [I’m not sure whether this link. will work.]


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