Making the strongest argument: Reply to Pepperberg (2015).

Abstract

Jaakkola (2014) argued that because the majority of studies of animals' understanding of invisible displacement did not adequately control for the use of alternative lower-level strategies, clear and solid evidence for a conceptual understanding of invisible displacement existed only for great apes. Pepperberg (2015) takes issue with this conclusion with respect to Grey parrots. While I agree that olfactory and social cueing may not be issues of concern for parrots, I reiterate the need for a study that adequately controls for associative learning before we can confidently claim that parrots understand invisible displacement.