Rethinking the Senses: Uniting the Philosophy and Neuroscience of Perception

Our everyday understanding of perception is that our sense organs enable us to see, touch, smell, taste and hear. The vocabulary of five distinct senses ramifies through descriptions of thought ("I see what you mean") emotion ("I was touched by her suffering") and aesthetics ("That's not to my taste"). Traditionally, philosophers have also thought that the five senses producing distinctive, separate conscious experiences. Equally, until recently, scientists have also studied each of the senses in isolation. But modern neuroscience is radically changing our understanding. Each sense organ contains many kinds of sensory receptors (think of all the different feelings from your skin). Everyday experiences - watching a film, eating a meal, walking along the street - involve different senses, working together. But most remarkable is a mass of recent research showing highly specific sensory interactions, in which one sense modifies the experience of another. Imagine listening to a syllable (say /ba/) spoken over and over, while watching a video of someone mouthing a different syllable (say /ga/), you actually hear the sound differently. Equally, the voice of a ventriloquist seems to come from the mouth of a doll some distance away. Somehow, what we see changes what we hear, presumably through processes that normally help us to associate sounds and sights correctly. Flavour provides the most surprising examples of sensory interaction, What we call the "taste" of food and drink is largely determined by smell rather than taste, but it also depends on the temperature and texture of food and drink, and its colour, and even the sounds that accompany eating. For instance, white noise reduces sensitivity to flavour (the so-called "aircraft food effect"). Equally, your sense of your own body can be changed by what you see and feel. If you look at a model hand being stroked with a brush, while your own hand, out of sight, is simultaneously stroked, you will soon feel that the model hand is part of you. The traditional view that information flows in one direction from basic sensation to perception, memory and action, has also been overturned. Recognising a spoken word, a familiar face, or a favourite piece of music draws on previous knowledge. Perception is influenced by memory, expectation, emotion and attention. Further, since our head, hands and eyes are constantly in motion, the brain must somehow stitch together perception from a sequence of sensory "snapshots". A comprehensive account of perception needs to begin with the relationships and interactions between the sensory modalities that produce our awareness of the world and of ourselves in it. Although the science of perception is moving very fast, it lacks the conceptual framework that philosophical thinking can bring to understanding the relationship between brain processes and experience. Our plan is for philosophers, psychologists and neuroscientists to work together in entirely new ways, including planning laboratory experiments together, to help us to understand how the brain puts together different sensory information, under the influence of past experience and expectation, to create the seamless flow of conscious experience, to identify objects and events in the world, to give us an sense of our own body, and to enable us to control our actions. We believe that our work will have wide impact beyond our university departments. It will help in the design of new forms of prosthetic devices to help deaf and blind people, and those who suffer untreatable pain, changes in body image or reduction in the sense of smell. It will inform the rapidly advancing technology of enhancement of sensory experience, cast light on the appreciation of the visual and performing arts, and stimulate new forms of preparation and presentation of food, and new understanding of the way in which people choose what products to buy, what works of art they prefer and what food they eat.