People spend a lot of time thinking about the past and the future (what is sometimes called mental time travel). Being able to remember the past, including what, how, and when things happened, can be very helpful in new situations when one is not sure how to behave. Planning for the future, and remembering to carry out those plans (called "prospective memory"), helps people prepare for things that are not immediately important but could be important hours, days, or even years from now (a simple example would be deciding what to pick up at the store on your way home from work and then remembering to do it). This ability to flexibly plan for the future has long been thought to be a uniquely human ability. In fact, it has been argued that animals are "stuck in time," and they cannot think about the past or future because their behavior is affected only by their current needs and surroundings. However, animals may show capacities for mental time travel, and such evidence would provide a better understanding of the evolutionary foundations of human memory and behavior. The NSF-funded research project conducted by Michael Beran, Emily Klein, and Theodore Evans at Georgia State University and Gilles Einstein at Furman University includes new tests of future-oriented thought and behavior in humans and three primate species (chimpanzees, rhesus monkeys, and capuchin monkeys). This project will test each species' ability to anticipate future situations and plan future actions so as to determine the relationship between the prospective memory and planning abilities of humans and other primates. Each species will perform computer tasks in which prospective memory is needed and future actions must be planned at the beginning of the task. One experiment will assess whether primates can learn to hoard food rewards that they have earned by working on a computer task, so that they can eat them later when they have fewer chances to earn rewards. Another experiment will test whether primates will use prospective memory to remember something that they need to do in the future. In some cases, primates may show that they can plan for future situations that are different from present ones, and this performance will be directly compared to human performance. This research will determine similarities and differences between primates and humans in their planning behavior and prospective memory and will help determine whether any of these abilities are unique to humans.
Failures of prospective memory and failures to plan for the future can have profound consequences for humans. Understanding the causes of such failures is important and can benefit from a broad scientific approach. This project will provide a better understanding of the evolutionary emergence, as well as the limits, of planning and future-oriented thought and memory in humans and primates. These studies offer new ideas about the nature of primate memory, the origins of planned behavior, and the nature of prospective memory.
Humans spend a lot of time revisiting the past and envisioning the future. Most adults can easily relay a story from their grade school days or describe plans for their future vacation. Such "mental time travel" and, in particular, anticipation of the future increases behavioral flexibility beyond what is needed under present circumstances. However, despite the obvious evolutionary advantages of being able to mentally travel through time so that one can predict what might be needed in the future, this ability has long been reserved for humans. According to some theorists, nonhuman animals are "stuck in time," confined to the present and limited to their current motivational states. Yet, it is impossible to evaluate this claim without appropriate behavioral tests. With the support of the National Science Foundation through this line of research, we investigated future-oriented cognitive processes in three nonhuman primate species (chimpanzees, rhesus monkeys, and capuchin monkeys), and often compared the animals’ performances directly to human performance. We can summarize the results of this project with three main conclusions. First, nonhuman primate species can anticipate future circumstances, and can plan their responses to those future needs accordingly. Second, some individuals show patterns of responding that indicate they are using prospective memory, the type of memory in which one remembers what one needs to do at a later time. Third, despite showing these behavioral and cognitive abilities, primates are limited when compared to adult humans. However, apes’ and monkeys’ future-oriented capacities may be similar to those of certain aged human children, but direct comparisons of performance between nonhuman primates and human children still are needed to fully assess this. More specifically, we have found that monkeys can learn to perform computer tasks that require them to anticipate what responses they will need to make later (typically, a few seconds to a few minutes later) and then remember those future responses and make them when they are appropriate. This involves some degree of planning those future responses, and also monitoring the environment for the correct time to make those responses. However, monkeys are not always successful in these kinds of tasks, and can struggle to anticipate certain kinds of future circumstances. On the other hand, humans can typically anticipate the future in all of these kinds of tasks, and this may indicate a critical role for things such as language or other executive functions that humans possess and that are the products of our more advanced cortical structures and the functioning of those structures. Throughout this research program, chimpanzees provided the strongest and most compelling support of prospective memory and the ability to anticipate the future. In a variety of tasks, chimpanzees assessed what they would need to do later to obtain a positive outcome, and then remembered to do just that when the time was right. These capacities certainly relate to future-oriented thought processes that afford humans the opportunities to design and build structures, modify environments for agriculture or industry, and coordinate future activity for the purposes of defense or commerce. These are some of the hallmarks of future-oriented thought, but they are built upon the same basic cognitive processes that deal with shorter-term, more limited future-oriented challenges, such as remembering to pick up milk on the way home, or to attach a file to an email one is about to send. That chimpanzees, and even monkeys, show evidence of these more limited future-oriented processes provides insight into the evolutionary emergence of these capacities, and also provides a framework for a comparative perspective grounded in the idea of shared capacities across species. Of course, humans exceed, in some cases substantially, the future-oriented processing abilities of these primate species, but the basic capacities – to anticipate, to encode what needs to be done later, and to remember to do those things later – are within the cognitive suite of capacities that we share with other primates. The findings from this research program have been widely reported in the scientific literature (journal articles), at scientific conferences, and through broader outreach activities such as visits by students, faculty, and members of the public to our laboratory to discuss these experiments and others. More broadly, nonhuman primate cognitive research has a wide appeal with the public, and research in our laboratory has been featured in dozens of popular magazines, websites, television shows on science channels, and in popular science books. The results of this program of research add to the consensus that understanding human nature requires situating human behavior and cognition properly within an evolutionary context. This is done by highlighting the unique aspects of human thought and behavior but also by recognizing the capacities for such things that we share with other animals.
