Picture Perception in Birds: Perspective from Primatologists.

The focus article questioned the validity of pictures to present real objects to birds, mostly because pictures are made for human eyes, and birds’ eyes have different functional properties. The authors agreed with the focus article, but went on to show that the issue of picture validity is similarly critical for primatologists, even when they study higher nonhuman primates with visual systems more similar to those of humans. The authors emphasized cognitive limitations in referential abilities that may be important sources of differences in picture processing modes between human and other animals. They further distinguished among three distinct cognitive levels of pictures processing, termed independence, confusion, and equivalence.