Frans de Waal in Aeon:
Scientists working on animal cognition often dwell on their desire to talk to the animals. Oddly enough, this particular desire must have passed me by, because I have never felt it. I am not waiting to hear what my animals have to say about themselves, taking the rather Wittgensteinian position that their message might not be all that enlightening. Even with respect to my fellow humans, I am dubious that language tells us what is going on in their heads. I am surrounded by colleagues who study members of our species by presenting them with questionnaires. They trust the answers they receive and have ways, they assure me, of checking their veracity. But who says that what people say about themselves reveals actual emotions and motivations?
This might be true for simple attitudes free from moralisations (‘What is your favourite music?’), but it seems almost pointless to ask people about their love life, eating habits, or treatment of others (‘Are you pleasant to work with?’). It is far too easy to invent post-hoc reasons for one’s behaviour, to be silent about one’s sexual habits, to downplay excessive eating or drinking, or to present oneself as more admirable than one really is.
No one is going to admit to murderous thoughts, stinginess or being a jerk. People lie all the time, so why would they stop in front of a psychologist who writes down everything they say? In one study, female college students reported more sex partners when they were hooked up to a fake lie-detector machine, demonstrating that they had been lying when interviewed without the lie-detector. I am in fact relieved to work with subjects that don’t talk. I don’t need to worry about the truth of their utterances. Instead of asking them how often they engage in sex, I just count the occasions. I am perfectly happy being an animal watcher.