Further informationson the exhibit "Weight delusion"
This example clearly shows that our senses work together. With our eyes we can see the difference in size. Our sense of touch confirms this difference in size. At this point our brain is involved, which has stored all impressions and experiences that we have had so far.
Normally, an object that is smaller is also lighter. Our brain expects this in that case as well. But the fact that the small cone is just as heavy as the large one confuses our brain - and it estimates the weight of the small cone to be greater than it actually is.