What’s a Pupil Worth? The Promise and Challenges of Cognitive Pupillometry in the Wild

This book chapter explores the concept of opportunistic sensing, focusing on the use of cognitive pupillometry to infer mental states and optimize behavior and performance in real-world applications. Controlled laboratory experiments suggest that cognitive pupillometry has great promise but faces challenges before it can be leveraged in complex environments or real-world contexts. Here, we consider the temporal characteristics of pupillary dynamics to discuss the opportunities and challenges of cognitive pupillometry. In short, the promise is that pupillary fluctuations reflect a range of cognitive states that can unfold over a broad range from a few seconds to days. The core challenge is developing appropriate models to map the temporal dynamics of both cognitive and non-cognitive (environmental) influences onto pupil data to isolate component processes in real-time in complex task environments. Specifically, the unitary nature of the pupil signal, controlled by both parasympathetic and sympathetic muscles, makes it challenging to infer causality between a component influence and measured pupillary fluctuation. We discuss future directions that can address open questions, including technological innovations and the need for more naturalistic datasets for model testing and development.