In their target article, Weisman and Spetch (2010) question the validity of pictures to present real things to birds, mostly because pictures are primarily made for the human eye, and not for the eye of birds with different functional properties. Here, we argue that this issue of picture validity is similarly critical for primatologists, even when they study the "higher" nonhuman primates with a more similar visual system, and emphasize cognitive limitations in referential abilities that may be

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... an important source of differences in picture processing modes between human and animals.