Accession Number:

ADA248479

Title:

Top-Down Influences on Bottom-Up Processing

Descriptive Note:

Annual rept. 20 Sep 1990-19 Sep 1991,

Corporate Author:

MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF BRAIN AND COGNITIVE SCIENCES

Personal Author(s):

Report Date:

1992-02-04

Pagination or Media Count:

9.0

Abstract:

Perception is not simply a bottom-up process, but involves inductive inferences that use top-down knowledge to interpret image data. In computational vision, typically this knowledge appears in the form of constraints such as rigidity, viewpoint consistency, smoothness, etc. However these constraints are fallible - they do not always apply, and hence the perceptual process entails inductive reasoning. A major theoretical thrust of our work is to provide a formal lattice framework for organizing the plausible states of this reasoning aspect of perception Jepson Richards. The proposal makes strong predictions, given a set of constraints and a particular picture as to what interpretations or percepts will be seen. Consequently we have a series of experiments underway to 1 understand which constraints or premises are typically invoked in the interpretation of simple line drawings and 2 to show that the lattice framework specifies all of these interpretations, placing them in proper rank order. In parallel, we are also exploring two other models for merging bottom-up and top-down information, both of which are neural-based. One, called sequence- seeking Ullman, proposes a network hierarchy where a sequence of transformations of both the input data and the target model occur in parallel, searching for the proper mapping that brings each into register. The proposal makes a special effort to incorporate what we currently know about cortical machinery, and also has triggered psychophysical experiments. We have not yet explored the relations between the lattice and sequence-seeking proposals. Finally, there are some studies related to our ability to switch between sets of premises, or to alter our models.

Subject Categories:

  • Biology

Distribution Statement:

APPROVED FOR PUBLIC RELEASE