Date of Award

Spring 6-2025

Document Type

Thesis (Ph.D.)

Department or Program

Psychological & Brain Sciences

First Advisor

Jonathan Phillips

Second Advisor

Matt van der Meer

Third Advisor

Steven Frankland

Abstract

This dissertation investigates the phylogenetic and developmental foundations of modal thought—the ability to contemplate possibilities, impossibilities, and alternative outcomes—and how this capacity supports adaptive decision-making. In Chapter 1, I provide a theoretical framework for studying modal cognition across non-human animals, focusing on counterfactual reasoning as a case study. I examine current methodologies and introduce the modal building blocks approach as a method for studying counterfactual thought in non-human animals. In Chapter 2, I present two empirical studies investigating rats’ capacity for counterfactual modal building blocks including hierarchical reward reasoning, non-habitual decision-making, and reasoning about available and unavailable options. In Chapter 3, I turn to developmental evidence in humans, examining how children generate and evaluate multiple possible options when solving open-ended decision problems. I show that children generate a similar number of options as adults and exhibit the “Take the First” decision heuristic from an early age. Finally, in Chapter 4, I summarize these findings, highlight outstanding questions, and propose directions for future research.

Available for download on Saturday, May 15, 2027

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