The Qualitative Character of Spatial Perception

Ordinary perceiving relies heavily on our sensing the spatial properties of objects, e.g., their shapes, sizes, and locations. Such spatial perception is central in everyday life. We safely cross a street by seeing and hearing the locations of oncoming vehicles. And we often identify objects by seeing and feeling their distinctive shapes. To understand how we perceive spatial properties, we must explain the nature of the mental states figuring in spatial perception. The experience one has when seeing a cube, e.g., differs from the experiences one has when seeing other shapes, e.g., spheres and pyramids. We must explain how such experiences differ to fully understand how we perceive differences in the spatial properties of objects. This presents a challenge often overlooked in philosophy and cognitive science. Whereas we can differentiate physical objects by their spatial properties, we cannot differentiate the experiences involved in perception in respect of their own spatial properties. Experiences are mental states, not physical objects, so they do not themselves have spatial properties; a visual experience of a 50 ft. tall cube, e.g., isn’t itself 50 ft. tall or cubical. So we must differentiate our perceptual experiences of those objects some other way, in terms of their own properties. I argue the experiences figuring in spatial perception have mental properties distinct from, but analogous to, the spatial properties we perceive. The experience one has when seeing a square, e.g., has a property that resembles and differs from other such mental properties in ways parallel to the ways physical squares resemble and differ from other shapes. Just as squares are more similar to rectangles than triangles, the mental property of an experience of a square is more similar to that of an experience of a rectangle than that of an experience of a triangle. I show how this theory helps solve several problems in philosophy and cognitive science; explaining change blindness, accounting for our ability to perceive combinations of distinct properties, e.g., color and shape, and determining whether the properties of experiences pertaining to the same spatial properties in different sensory modalities are themselves the same