Although any farmer or pet owner throughout the ages would probably agree that animals can understand the intentions of their owners, not until 1978 has this knowledge been scientifically proven.
Premack & Woodruff (1978) performed a very simple experiment in which they showed videos to a female adult chimpanzee named Sarah involving humans facing various problems, from simple (can’t reach a banana) to complex (can’t get out of the cage). Then, the chimps were shown pictures of the human with the tool that solved the problem (a stick to reach the banana, a key for the cage) along with pictures where the human was performing actions that were not conducive to solving his predicament. The experimenter left the room while the chimp made her choice. When she did, she rang a bell to summon the experimenter back in the room, who then examined the chimp’s choice and told the chimp whether her choice was right or wrong. Regardless of the choice, the chimp was awarded her favorite food. The chimp’s choices were almost always correct when the actor was its favourite trainer, but not so much when the actor was a person she disliked.
Because “no single experiment can be all things to all objections, but the proper combination of results from [more] experiments could decide the issue nicely” (p. 518), the researchers did some more experiments which were variations of the first one designed to figure out what the chimp was thinking. The authors go on next to discuss their findings at length in the light of two dominant theories of the time, mentalism and behaviorism, ruling in favor of the former.
Of course, the paper has some methodological flaws that would not pass the rigors of today’s reviewers. That’s why it has been replicated multiple times in more refined ways. Nor is the distinction between behaviorism and cognitivism a valid one anymore, things being found out to be, as usual, more complex and intertwined than that. Thirty years later, the consensus was that chimps do indeed have a theory of mind in that they understand intentions of others, but they lack understanding of false beliefs (Call & Tomasello, 2008).
1. Premack D & Woodruff G (Dec. 1978). Does the chimpanzee have a theory of mind? The Behavioral and Brain Sciences, 1 (4): 515-526. DOI: 10.1017/S0140525X00076512. ARTICLE
2. Call J & Tomasello M (May 2008). Does the chimpanzee have a theory of mind? 30 years later. Trends in Cognitive Sciences, 12(5): 187-192. PMID: 18424224 DOI: 10.1016/j.tics.2008.02.010. ARTICLE | FULLTEXT PDF
By Neuronicus, 20 August 2016