It's hard to say. Maybe it's a mix. Here's a counterexample: http://similar-images.googlelabs.com/images?q=apple&qtype=similar&tbnid=npK3gwxTq2ePJM&prev=/image

It's hard to say. Maybe it's a mix. Here's a counterexample: http://similar-images.googlelabs.com/images?q=apple&qtype=similar&tbnid=npK3gwxTq2ePJM&prev=/images%3Fq%3Dapple&tprev=/images%3Fq%3Dapple http://similar-images.googlelabs.com/images?q=apple&qtyp...