Our expectations have a measurable effect on how our brains process information, according to a recent study at the Radboud University, at the Donders Institute for Brain, Cognition and Behaviour in Nijmegen.

Although we tend to believe that we see the world around us as it really is, how we perceive reality is strongly influenced by our expectations. Prior knowledge of our surroundings and the world in general help us recognise objects and people quickly and accurately, even when the image we receive is noisy or unclear, such as cyclists in the park at dusk, or athletes playing a given sport on a TV with bad reception.

During the study at RU, participants' brain activity was monitored with an MRI scanner as they were shown both expected and unexpected images. When participants viewed expected images, regions of the brain known to be involved in visual processing were less active than when they viewed unexpected images.

Surprisingly though, these regions contained a clearer representation of the expected images than of the unexpected ones. This "clearness" was determined by using a so-called "brain-decoder," a computer algorithm that attempted to decode which image a participant saw based on their brain activity.

As it turns out, the brain-decoder was more successful at decoding brain activity and correctly linking it with expected images than unexpected ones, an indication that the activity in these brain regions contained a less ambiguous signal for expected images.

Based on the study, the researchers conclude that expectations lead to less but more effective processing in the human brain.

Published in the journal Neuron. You can read the abstract and link to a (paid) copy of the full report here.