Seeing the whole reduces access to its parts.

The content of our conscious experience is automatically dictated by higher level stages of visual processing, which are associated with the representation of more abstract and meaningful interpretations. Poljac et. al. show that the ability to form a more abstract representation of a given visual input (in terms of a particular object) does not simply mean that the details of this stimulus are not immediately or automatically accessible to conscious perception, but that these details become fundamentally less accessible. The whole decreases access to the parts.

The experiments used computer generated walking dot figures of humans, both upright (easy to form the gestalt as human walking), and upside-down (more difficult to form the gestalt), as well as random stationary or moving dots. The rates of changes in dot colors were not perceived as well in the upright walking figures which generated the clearest gestalts.

They suggest that the rapid extraction of a perceptual Gestalt, and the inaccessibility of the parts that make up that Gestalt, may in fact reflect two sides of the same coin whereby human vision provides only the most useful level of abstraction to conscious awareness. This whole point is explained very beautifully in Metzinger's book, "The Ego Tunnel." (I did a series of five daily posts on this post, starting on 6/30/09)