Abstract
In one way or another, most research in Perception is concerned with sensory individuals, which are meant here in the sense of perceptual objects. For example, the stimuli presented to participants in a typical experimental study can often be considered as instances of sensory individuals (or perceptual objects), irrespective of whether the research question at hand is explicitly about object processing. But what exactly constitutes a perceptual object? This seemingly simple question quickly turns into a “metaphysical rabbit hole” (p. 95) if the scope of analysis is broadened from ordinary material objects (i.e., prototypical perceptual objects) to visual ephemera such as rainbows or clouds, sounds, or odors, let alone to the crossmodal nature of many objects and events in our environment. In their book, Mroczko-Wąsowicz and Grush delve into these intricate aspects of unisensory and multisensory object processing with a curated collection of chapters written by distinguished scholars from philosophy, experimental psychology, and cognitive neuroscience.
The interdisciplinary approach taken by the editors as well as the centrality of sensory individuals as the basic building blocks of human perception make this book unique and essential reading for a wide range of researchers with an interest in perception. The topics covered by the individual chapters range from intriguing summaries of recent experiments on “non-sensory individuals” that frequently arise when looking at regular scaffold patterns such as grids (Chapter 5 by Ongchoco & Scholl), over excellent reviews of the neural mechanisms underlying auditory object perception (Chapter 9 by DiTullio & Cohen), to profound philosophical analyses of whether perceptual experiences of persistence are ever constitutively multisensory (Chapter 20 by Green), to mention but a few. For the most part, this eclectic view on the topic of sensory individuals works applaudably well, and I found the frequent changes in viewpoint particularly enriching during my own read-through of the 23 chapters despite some rather rough transitions between topics. However, as an edited volume, the book offers the flexibility for the individual chapters to be read as stand-alone articles, catering to readers with more focused interests in specific aspects of object perception.
In terms of the organization of the content, Mroczko-Wąsowicz and Grush divide their book into three parts, starting with a section on conceptual and methodological issues in studying sensory individuals (Part 1), followed by sections dedicated to research on unimodal (Part 2) and crossmodal (Part 3) sensory individuals. Part 1 should not be mistaken for an introduction to the topic; while some chapters do nicely set the stage for the subsequent parts by discussing what constitutes a perceptual object (Chapter 2) and how object perception might vary between individual observers (Chapter 6), others immediately engage with a diverse set of topics such as the development of object concepts during infancy (Chapter 1) and more specific aspects of visual binding and object formation (Chapters 3–5) which might also have fitted into the later parts of the book. By contrast, the subsequent parts appear more coherent. Part 2 discusses unimodal sensory individuals in the visual (Chapters 7 and 8), auditory (Chapters 8–10), tactile (Chapter 11), and olfactory (Chapters 12–14) modalities. Part 3 expands into the crossmodal aspects of object perception (Chapters 15–20), ending with some more specific instances of sensory individuals such as faces (Chapter 21), pain (Chapter 22), and two-dimensional pictures (Chapter 23). In addition to the structure given by these three parts, an introductory chapter outlines alternative groupings of the content, which I found to be a clever and beneficial feature that further strengthened the connections between the individual chapters.
It is an achievement of the book that most readers will likely find familiar as well as discover new perspectives on the topic of sensory individuals. As an experimental psychologist, I particularly gained from the more philosophically oriented chapters that are outside my usual area of reading. However, potential readers might want to calibrate their expectations about what this book does and does not aim to achieve. First, while individual chapters might work well as teaching materials, the book clearly is not intended as an introductory textbook on sensory individuals but rather is a collection of (sometimes conflicting) pieces with vastly different foci. For instance, readers might learn about the theoretical distinction between the perceptual objects of orthonasal and retronasal olfaction (Chapter 14) to then later discover that “psychophysical studies reveal that (sub-threshold) tastants are integrated with olfactory stimuli in essentially the same manner, regardless of whether the latter happen to be delivered via the orthonasal or retronasal routes” (Chapter 16, p. 285). It is this coexistence of different approaches and findings that makes the book inspiring to read. Second, despite its commendable interdisciplinary approach, the book tends to favor philosophical perspectives, with relatively few (but excellent) contributions from a genuine neuroscience perspective. This imbalance might have also led to some confusion in terminology across disciplines. For example, the frequent use of the term multimodal throughout the book might surprise many in the multisensory research community who have abandoned this term in favor of the less ambiguous alternatives crossmodal to refer to physical stimuli and multisensory to refer to perceptual and neural processes associated with multiple sensory modalities (Stein et al., 2010). Finally, developmental research approaches, which are highly relevant for clarifying questions about the nature of sensory individuals, are discussed only sparsely. A future edition of the book could potentially benefit from including topics such as visual and crossmodal object perception in sight recovery individuals who had experienced a transient period of congenital blindness (e.g., Held et al., 2011; Röder et al., 2013).
These minor critiques are not meant to detract from the substantial contribution this book makes to advancing our understanding of sensory individuals across various disciplines. It is therefore unfortunate that the £100 price tag for the print version may limit its accessibility to some readers. However, those who invest in this volume will be rewarded with a compelling, multifaceted exploration of current research on sensory individuals that will captivate philosophers, psychophysicists, and neuroscientists with an interest in perception alike.
