The Effect Of Top-down Knowledge In Size Illusior

Previous studies found that the ball presented at a more distant position will beconsidered lager than that presented at a less distant position in the plane of the rendering3Dscene, though the full sizes of them are equal.fMRI research futher found that the more distantball activated the outer layer of the V1on the primary visual cortex area, while the less distantball activated the central part of V1.,Furthermore, it was found that the size illusion will beaffected by attention. Thus, such size perception may attribute to a top-down feedbackmechanism of brain cortex. This research will exploration the top-down effect of size illusionfrom the ERPs. The study1which with ERP experiment and behavior experiment willmeasure the normal size illusion use ERP to watch the base composition. There are twovariable in the ERP experiment. The first one is the location of the checkball,far or near,thesecond one is the strong or weak checkball. The result show that the checkball activate the C1composition and the P1composition and the far amplitude larger than near amplitude. Thestudy2change checkball to football to watch the top-down feedback influence to the sizeillusion. The result show that far location has the larger amplitude than near location inC1composition and near location has larger amplitude than far location in P1composition.The two studies show that the top-down feedback will influence the course of working of thesize illusion not the Behavioral symptoms.