When a disease affects the brain-body relationship, the placebo response can confound researchers.
If you are a cat’s human friend, he cares when you talk to him. Whether he will, or even can, do what you want is a separate question.
The birds themselves are not agents making a moral choice to deceive; they are carrying out a behavior pattern they have inherited.
Many would be surprised to learn that either head had any personality at all, and yet…
Is not the fact that we are having these discussions the best available evidence that we are not “just overgrown apes or undergrown apes”?