Selected Rest Frames and Cognition

Selected rest frames have been presented in this dissertation as a purely perceptual phenomenon, although affected by cognitive issues such as the focus of attention (see Section 3.3.1). An interesting question is to what extent selected rest frames operate on principles similar to cognition.

An analogy can be drawn between the operation of the selected rest frame and of chunking. ``Chunks'' refer to familiar patterns stored in long-term memory. Human information processing makes heavy use of chunking. A complex pattern of information which has been chunked is often easier to process than a smaller amount of unfamiliar information. An interesting recent example of this is provided by Luck and Vogel [63], who mention that

...objects defined by a conjunction of four features can be retained in working memory just as well as single-feature objects, allowing sixteen individual features to be retained when distributed across four objects. Thus, the capacity of visual working memory must be understood in terms of integrated objects rather than individual features...

Chunks underlie memory of the environment. Chase and Simon [18] found that while expert chess players are better at remembering meaningful chess positions than are novices, the two groups perform equally poorly on random chess positions. Experts chess players (and, presumably, humans in general) remember by breaking the environment into previously-learned patterns.

The same chunking which drives both short-term and long-term memory is also active in visual perception. There are numerous visual illusions which imply that the perceptual system seeks familiar patterns (chunks), to the extent that it can be fooled when the pattern is not entirely there.

It seems likely that the nervous system does not merely look for and remember chunks: it also represents unfamiliar information in terms of its differences from known chunks. It is more efficient to view new information as ``almost like such-and-such except for...'' than it is to analyze new information from scratch. Viewed in this way, one's set of chunks do not simply define a set of isolated points: they define a coordinate system in terms of which new information can be represented.

This resembles the role hypothesized for the selected rest frame. The selected rest frame is hypothesized to serve as the comparitor for spatial judgments. Spatial judgments are made by describing how things relate to (are different from) the selected rest frame.

This suggests that the selected rest frame can be thought of as the ``underlying chunk'' for spatial perception. Selected rest frames may therefore be closely related to the operation of chunking in cognition.

Human Interface Technology Lab