UC Santa Cruz

Philosophical Dimensions of the Morris Water MazeJordan Dopkins

In 2014, John O’Keefe was awarded the Nobel Prize in Physiology or Medicine for his work on the hippocampus and its role in encoding map-like representations. His contributions were significantly influenced by Morris water maze studies. O’Keefe himself acknowledged the pivotal role of the Morris water maze, stating that it remains the preeminent behavioral assay for assessing hippocampal function. Indeed, thousands of researchers have turned to the Morris water maze for evidence about navigation abilities and the effects that stress, lesions, pharmaceutical interventions, and more can have on them. This body of studies constitutes an important scientific enterprise.

This dissertation is about some of the philosophical dimensions of Morris water maze studies. Chapter 1 is about the different types of information states (including representational states) found across hypotheses about Morris water maze performance. Chapter 2 is about systematic task failures reported in Morris water maze studies. I argue these impose a constraint on what can count as an explanation (a good hypothesis) of task success. While this has the air of a chopping block for scientific hypotheses, I see things a little differently. In Chapter 3, I argue that satisfying the constraint is a formidable challenge for any hypothesis. One that should make researchers second-guess the concepts and strategies employed to explain the roles information states play in the maze task. Chapter 4 focuses on two spatial concepts. I argue that researchers working definitions for the spatial concepts of distal (far) and proximal (near) in maze studies are problematic. They are not ecologically valid, and so claims about them do not generalize to real-life navigation behaviors like migration or scavenging behaviors. Following this, I present alternative definitions in terms of neural information about visual cues. The neural information relevant to this account is non-conceptual, and so it provides a sketch of the ways in which information states can fruitfully contribute to explanations of rat success and failure while maintaining ecological validity.

To sum, this dissertation navigates some important philosophical dimensions of Morris water maze studies, illustrating the challenges and opportunities involved in using information states to explain and understanding animal navigation.