| Information from the environment reaches us through several distinct senses. Within each of these senses information about different aspects of the environment are processed independently. For example, in vision information about an object's colour is processed independently of information about its motion. Such separations are easy to explain if we consider the differences between the optimal ways to register and analyse different kinds of information. There is at present little doubt that information about different attributes is processed separately. There is less agreement about the extent to which the processing is independent. Moreover, it is generally explicitly or implicitly assumed that the separately analysed attributes must later be recombined in some way. For the latter the brain must keep track of which bits of information belong together. The topographic organisation of receptive fields within the visual system suggests that such binding is based on spatial information. In the proposed project we intend to examine whether the information is synchronised before being combined, whether any check for consistency takes place when combining the attributes, and whether such binding always takes place, or only when this is necessary for the task at hand. We already have some evidence that separate aspects of a single action can be driven independently by different sources of information. We also have evidence based on perceptual judgements that different sources of information about a single attribute are not combined automatically. We will pursue these issues by examining the extent and accuracy of binding using a variety of psychophysical techniques. Our working hypothesis is that the brain combines as little information as possible for the task at hand. Thus rather than striving for a unified representation of the world, with elaborate binding mechanisms, our brain tries to avoid the binding problem whenever possible, and uses very simple binding rules when forced to combine information that has to be processed separately. |
