[The "filling-in-trap". Our sences deceive us].

We use various strategies in order to attain a complete knowledge of reality. One of these is using "filling-in". What is and is not filling-in is discussed. The brain may process light which reaches the retina in two fundamentally different ways. The conclusion is that many a patient with perimetrically verifiable visual field defects with each eye separately experiences a complete image of his total surrounding. The quality of this image correlates to the neuronal capacity of the retina in question. What generally has been assumed to be due to filling-in is in this specific instance a newly discovered faculty in the system consisting of eye and brain naively, we have walked straight into the trap of blaming this faculty on filling-in.