Donders Institute for Brain, Cognition and Behaviour
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Thesis defense Elexa St. John-Saaltink (Donders series 256)

5 December 2016

Promotor: prof. dr. P. Hagoort, dr. F. de Lange

When the past influences the present: Modulations of the sensory response by prior knowledge and task set

Natural visual input is highly complex. Scenes often contain multiple objects at various distances, with some objects only partially visible. One way in which the visual system is able to make sense of this information efficiently is by making use of prior experience with the world: what is likely to be in the visual input based on the types of things that have previously encountered?

In this thesis I investigated how prior experience influences the way in which the brain responds to the sensory environment, and consequently shapes how we perceive the world. Specifically, I examined how visual information is processed by the brain depending upon the circumstance in which it arrives: what input preceded it, to what extent a certain stimulus was able to be predicted, and which cognitive resources were available. I found that perception was influenced by what was seen just before, and that this bias was reflected in the neural signal. I also found that task set can influence how the brain makes use of predictive information.