Abstract
The history of modern psychology is in large part the history of rodents finding their way through mazes. With rodents navigating in mazes as a starting point, human spatial navigation has likewise been studied using modern methods for over a century (e.g., Perrin, 1914). It is perhaps surprising then that there is no comprehensive textbook dedicated exclusively to synthesizing what is known about human navigation (but see Dudchenko, 2010 for a rodent-centric view). Four leading experts fill this long overdue gap in Human Spatial Navigation. This book offers a wide-ranging and engaging introduction to the cognitive and neural mechanisms underlying human navigation in health and disease as well as the psychological and neuroscientific methods used to study human wayfinding. The strength of this book comes from its breadth, not depth; as such, this book is particularly suitable for students and researchers new to the field of navigation.
Human Spatial Navigation begins with anecdotes of humans successfully navigating under difficult circumstances, such as Puluwat seafarers navigating the open ocean with no mechanical aids (Chapter 1). These anecdotes are used to introduce core concepts in human navigation research, such as a “cognitive map” (i.e., an internal representation of the relative positions of locations in the external world) as well as the tools used to study human navigation’s neural basis (e.g., functional magnetic resonance imaging). Chapter 2 surveys foundational behavioral studies of human wayfinding and spatial cognition, covering now-standard behavioral tasks (e.g., Judgment of Relative Direction and triangle completion) and their associated dependent measures (e.g., direction and distance estimations). This chapter also illustrates how navigation is not a process pure ability—an important point often overlooked by studies that treat the brain’s “navigation system” as monolithic—and discusses how domain general confounds can be controlled in behavioral research. Chapter 3 introduces the neural mechanisms supporting human navigation. Following in the tradition of O’Keefe and Nadel’s The Hippocampus as a Cognitive Map (1978), Chapter 3 focuses on the role of the hippocampal formation in mediating cognitive map-like representations, but also highlights some limitations to this idea that are especially germane to human navigation.
Chapters 4 to 6 summarize what is known about the cognitive and neural bases of visually guided navigation, goal-oriented navigation, and multiple types of spatial memory, respectively. By assessing the extent to which homologous mechanisms underlie each of these navigational abilities in humans and rodents, Chapters 4 to 6 offer a refreshing new perspective. While resemblances between human and rodent navigation systems underscore their evolutional continuity, it often leads the field to overlook crucial differences between species. For instance, the authors argue that differences between rodent and human capacities for vision and communication cause the two species to possess qualitatively different spatial abilities. Human Spatial Navigation just scratches the surface with respect to these cross-species differences. For example, there is little consideration of how impairment of the human visual system affects navigation (e.g., Schinazi, Thrash, & Chebat, 2016). Likewise, although the authors focus on how language and symbols help humans share and encode spatial information, they do not discuss whether or how linguistic differences between people influence navigation (e.g., Majid, Bowerman, Kita, Haun, & Levinson, 2004). Nevertheless, Human Spatial Navigation makes a strong case that we cannot learn everything about (human) navigation from studying rodents.
Chapters 7 and 8 provide an excellent introduction to how human wayfinding abilities break down following brain lesions, in healthy aging and in cases of Alzheimer’s disease and developmental topographic disorientation. Neuropsychological research reviewed suggests that the brain’s navigation system consists of multiple topographically organized regions, each of which is causally involved in performing unique spatial computations.
Chapter 8 also critically contrasts this functional neural specialization view with the idea that a distributed network of brain regions, not one of which performs a unique function, mediates navigation. A limitation of this chapter, which highlights a general weakness of the book for readers already familiar with navigation research, is that the authors tend be noncommittal in areas of ongoing debate. Concerning debate over regional specialization versus distributed processing, for example, the authors conclude, “the truth is somewhere between” (p. 145). While this conclusion is undoubtedly correct, the reasons given for this middle-path view remain unsatisfying. For example, two major lines of evidence against specialization are given. First, canonical mappings between brain structures and navigational computations are not entirely consistent with the data (e.g., environmental familiarity modulates spatial representations, and this is unaccounted for in standard function-structure mappings). Second, behavioral tasks designed to isolate specific computations can be confounded by domain general factors, making it difficult to assign unique spatial functions to particular brain areas. Yet, the first point simply argues for a more nuanced account of regional specialization than originally proposed; Human Spatial Navigation would have been the perfect opportunity to gesture toward such a view, including suggestions of how this view could be explored in future experiments. Concerning the second point, it is not clear which studies in particular the authors think are confounded by extraneous factors.
Human Spatial Navigation concludes with a discussion of how much of the brain’s navigation network overlaps with regions known to support general mnemonic functions (Chapter 9). Indeed, spatial computations traditionally studied in the context of navigation operate in many domains beyond wayfinding, including perceptual domains like vision (Nau, Julian, & Doeller, 2018) and audition (Aronov, Nevers, & Tank, 2017), and this book reinforces the idea that human navigation research could serve as a framework for understanding how this is the case.
Any book of this scope must be necessarily selective. One particularly notable omission is the development of navigational abilities during early life, an area of research essential for understanding the ontogenetic origins of human navigation, as well as a historically important testbed for competing theories of spatial cognition. Nevertheless, Human Spatial Navigation provides an accessible and exciting synthesis of most major topics in human wayfinding, making it an outstanding resource that will likely be a fount of insight to those lost in the human navigation literature maze.