Spatial Layout Perception, Neural

What is “Perception”?

There are many aspects of our experience of spatial layout. For example, on a clear, dry day, a distant mountain may look relatively close—perhaps only 10 kilometers (km) away. However, our past experience (or a map) may tell us that the mountain is really 50 km away. If we are stuck in traffic and in a hurry to get there, the mountain may seem to be 100 km away, in a more abstract sense. Which of these should we consider to involve perception of spatial layout? This is an important question, because different neural mechanisms are likely to be involved depending on how one conceives of the term perception. The mountain example demonstrates that our expectations, prior experiences, and motivations (sometimes collectively called top-down factors) can play a role in shaping how we experience spatial layout, over and above what our senses tell us. While recognizing that the boundaries between concepts are likely to be fuzzy, many researchers define spatial layout perception in a way that largely excludes top-down influences. In this view, the perceived distance to the mountain would be 10 km. The neural pathways associated with top-down influences are poorly understood; because these influences involve complex comparisons between environmental features and information stored in long-term memory, the medial temporal and frontal lobes likely play a role. At any rate, the focus in this entry will be on the neural basis for spatial layout perception, considered separately from top-down factors.

Another important consideration is that spatial layout perception often carries the connotation that the perceiver is consciously aware of the layout of objects in the environment. This connotation is important because we may not always be [Page 903]aware of the spatial representations that the brain builds and uses. For example, the brain mechanisms that control eye movements, reaching, and other actions often rely on information about the spatial layout of objects in the environment, but these action-based spatial representations can come and go without necessarily influencing our awareness of spatial layout. This opens the possibility that the consciously perceived location of a coffee cup in front of us might be different than the internal coordinates the brain uses for the purpose of reaching to it. Many researchers do not consider these action-based representations to be perceptual in nature because they primarily exist outside conscious awareness.

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