Mental Time Travel in Great Apes?
Final Report Abstract
The main aim of this project was to investigate mental time travel abilities in Great Apes and to examine whether these animals travel mentally in time in the same way that humans do. Following the suggestion of Tulving (1993) and Suddendorf et al (1997), I wanted to investigate whether similar mechanisms are responsible for travelling into the past as into the future. Therefore I conducted 2 studies to find out how apes solve problems about the past and 2 studies about the future. In the first study, I wanted to investigate the ability of apes to remember a sequence and to imagine that this sequence will be continued even when the subject itself cannot respond to it. Therefore apes had to learn the order in which rewards were hidden under one of three cups. The question was whether they understand that the sequence in which the reward is hidden will continue when a rival retrieves the reward. However, as the subjects were not able to learn the sequence sufficiently well – which was the precondition for the test - I had to terminate the experiment. In the second study, I raised the question how apes (and domestic dogs) remember and represent hidden objects. I was able to show that that apes and domestic dogs are able to individuate hidden objects according to their properties/kind in comparable ways. In the third study, I raised the question whether apes protect tools from conspecifics to use these tools in future in order to get food. Although the tested apes had done so in previous experiments, they did not save the correct tools in this study. I concluded that subjects had forgotten the tool because they were distracted and had access to low quality food in the meanwhile. Future studies might increase the benefit of the tool use and thereby increase the motivation of the subjects to save and protect the appropriate tool from conspecifics. In the fourth study I tested whether apes would produce tools for future use. Subjects had access to a baited apparatus only for a limited duration and therefore should use the time preceding this access to create the appropriate tools in order to get the rewards. Apes were able to prepare tools in advance for future use, and they produced them mainly in conditions when they were really needed. These results can be added to the recent debate about the ability to travel mentally in time in nonhuman animals. There is now growing evidence that animals are able to remember what, where and when an event happened and that they plan for the future, some without reference to their current motivational state. It is likely that – as in other areas of cognition – although humans outperform apes, the difference between the two species are not as huge as was previously thought.
