Casey O'Callaghan

Casey O'Callaghan

​Professor of Philosophy and Philosophy-Neuroscience-Psychology
PhD, Princeton University
research interests:
  • Philosophy of Mind and Perception
  • Metaphysics
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    • Washington University
      CB 1073
      One Brookings Drive
      St. Louis, MO 63130-4899
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    Professor O'Callaghan's research focuses on philosophical questions about perception. In particular, he has written about auditory perception and the nature of its objects and about multisensory perception and consciousness. ​

    Casey O'Callaghan's work stems from a more general interest in how perceptual awareness relates to its objects and how it shapes our understanding of the natures of those objects.

    Recently, he has been writing about speech perception, the significance of interactions among sense modalities for theorizing more generally about perception, how to differentiate the senses, how perception differs from extra-perceptual cognition, and psychological explanation and taxonomy.

    Some essays on these topics are collected in Beyond Vision, published by OUP in 2017. Currently, he is writing a monograph on multisensory perception and consciousness called A Multisensory Philosophy of Perception.

    A Multisensory Philosophy of Perception

    A Multisensory Philosophy of Perception

    Most of the time people perceive using multiple senses. Out walking, we see colors and motion, hear chatter and footsteps, smell petrichor after rain, feel a breeze or the brush of a shoulder. We use our senses together to navigate and learn about the world. In spite of this, scientists and philosophers alike have merely focused on one sense at a time. Nearly every theory of perception is unisensory. This book instead offers a revisionist multisensory philosophy of perception. Casey O'Callaghan considers how our senses work together, in contrast with how they work separately and independently, and how one sense can impact another, leading to surprising perceptual illusions. The joint use of multiple senses, he argues, enables novel forms of perception and experience, such as multisensory rhythms, motions, and flavors that enrich aesthetic experiences of music, dance, and gustatory pleasure.

    Beyond Vision: Philosophical Essays

    Beyond Vision: Philosophical Essays

    Beyond Vision brings together eight essays by Casey O'Callaghan. The works draw theoretical and philosophical lessons about perception, the nature of its objects, and sensory awareness through sustained attention to extra-visual and multisensory forms of perception and perceptual consciousness. O'Callaghan focuses on auditory perception, perception of spoken language, and multisensory perception. The first essays concern the nature of audition's objects, focusing on sounds, especially drawing attention to the ways in which they contrast with vision's objects. The middle essays explore forms of auditory perception that could not be explained without understanding audition's interactions with other senses. This bridges work on sound perception with work on multisensory perception, and it raises multisensory perception as an important topic for understanding perception even in a single modality. The last essays are devoted to multisensory perception and perceptual consciousness. They argue that no complete account of perception overall or of multisensory perceptual consciousness can be developed in modality-specific terms-perceiving amounts to more than just seeing, hearing, touching, tasting, and smelling at the same time. The final essay presents a new framework for understanding what it is to be modality-specific or to be multisensory.

    Sounds: A Philosophical Theory

    Sounds: A Philosophical Theory

    Vision dominates philosophical thinking about perception, and theorizing about experience in cognitive science traditionally has focused on a visual model. This book presents a systematic treatment of sounds and auditory experience. It demonstrates how thinking about audition and appreciating the relationships among multiple sense modalities enriches our understanding of perception. It articulates the central questions that comprise the philosophy of sound, and proposes a novel theory of sounds and their perception. Against the widely accepted philosophical view that sounds are among the secondary or sensible qualities, and against the scientific view that sounds are waves that propagate through a medium such as air or water, the book argues that sounds are events in which objects or interacting bodies disturb a surrounding medium. This does not imply that sounds propagate through a medium, such as air or water. Rather, sounds are events that take place in one's environment at or near their sources. This account captures the way in which sounds essentially are creatures of time and situates sounds in the world. Sounds are not ethereal, mysterious entities. It also provides a powerful account of echoes, interference, reverberation, Doppler effects, and perceptual constancies that surpasses the explanatory richness of alternative theories. Investigating sounds and audition demonstrates that considering other sense modalities teaches what we could not otherwise learn from thinking exclusively about the visual. This book concludes by arguing that a surprising class of cross-modal perceptual illusions demonstrates that the perceptual modalities cannot be completely understood in isolation, and that a visuocentric model for theorizing about perception — according to which perceptual modalities are discrete modes of experience and autonomous domains of philosophical and scientific inquiry — ought to be abandoned.

    Sounds & Perception

    Sounds & Perception

    This book comprises original chapters that address the central questions and issues that define the emerging philosophy of sounds and auditory perception. This work focuses upon two sets of interrelated concerns. The first is a constellation of debates concerning the ontology of sounds. What kinds of things are sounds, and what properties do sounds have? For instance, are sounds secondary qualities, physical properties, waves, or some type of event? The second is a set of questions about the contents of auditory experiences and of hearing. How are sounds experienced to be? What sorts of things and properties are experienced in auditory perception? For example, in what sense is auditory experience spatial; do we hear sources in addition to sounds; what is distinctive about musical listening; and what do we hear when we hear speech? An introductory chapter summarises many of the issues discussed, provides a summary of the contributions and shows how they are connected.