Although we find the idea of representation by similarities
attractive as such, we have two main objections to the specific
proposal of Edelman. First, he does not consider complexity issues in
terms of storage and speed of recall for recognition. Related to this,
the appearance of objects depends on far more factors than just
shape, illumination, and pose. This requires an intermediate shape
abstraction process that extracts category-specific shape properties
from the mixed appearance of images.