NSF Award
2418389
How many windows are in your house or apartment? In answering this question most people visualize their dwelling as they imagine walking around to count the windows. Surprisingly, about 7% of people answer this question correctly but do not “see” their home in their mind. Such people are “aphantasic” meaning that they do not experience images in their mind. The fact that aphantasics can answer such questions without “seeing” their home, suggests a need to change the understanding of how people with and without aphantasia manage to think about things that are not present. While people with aphantasia are able to do things like counting windows without experiencing images, they differ from people without aphantasia in that their pupils do not change size when they think about bright objects, like the sun. This difference means that measuring the size of people’s pupils can be used to determine whether or not they are experiencing imagery. This pupil-based method of measuring imagery will then be able to determine whether other animals, like apes and monkeys, use visual imagery. Determining whether other animals experience imagery is critical for understanding how visual imagery evolved, what purpose it serves in human thinking, and provides better animal models to use in research to understand and improve human mental health.<br/><br/>At this point, it is unclear whether experiments done with people with aphantasia can be extended to other animals. This project tests whether the experiments conducted previously with humans are correct and extends them to conditions that will allow tests with other primates, like monkeys and orangutans. Humans are tested in several experiments that determine whether their pupils change size when they think about bright objects. For instance, people are asked to think about the sun while they are looking at an image of a neutral brightness. If their pupils contract more when they think about the sun than when they think about darkness, this shows that what they think about affects the size of their pupils and that they are probably seeing an image in their mind. These experiments are then modified in ways that allow them to be used with monkeys and apes, and are readministered to humans, to determine if pupil size still indexes mental imagery. This set of experiments provides the necessary preconditions that for eventual experiments with apes and monkeys, allowing these results to be compared with results from humans. The work will be done in part by graduate students and undergraduate students who will receive training in doing the type of cross-species research that advances understanding of human mental function and develop better animal models for biomedical research. This project broadens participation in STEM research through a variety of mechanisms, including mentored research experiences for undergraduates from historically black colleges and universities.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
