Xref: utzoo ont.events:1380 uw.talks:72 uw.cs.grad:61 Path: utzoo!utgpu!watmath!watdragon!ylkingsbury From: ylkingsbury@watdragon.waterloo.edu (Yvonne Kingsbury) Newsgroups: ont.events,uw.talks,uw.cs.grad Subject: ICR Colloquium Keywords: "Using Spatial Coherence as a Local Teacher for a Neural Network". Message-ID: <18244@watdragon.waterloo.edu> Date: 16 Nov 89 16:52:06 GMT Distribution: ont Organization: U of Waterloo, Ontario Lines: 53 The University of Waterloo 200 University Avenue Waterloo, Ontario The Institute of Computer Research (ICR) Presents a Colloquium on Using Spatial Coherence as a Local Teacher for a Neural Network by Dr. Geoffrey Hinton of Dept. of Computer Science and Psychology, University of Toronto DATE: Wednesday, November 22, 1989 TIME: 3:30 p.m. LOCATION: William G. Davis Computer Research Centre, Room 1302 ABSTRACT A major goal of research on unsupervised learning procedures is to discover an objective function that defines the quality of an internal representation without any externally supplied information about the desired outputs of the system. If such a function could be found, it should allow a hierarchy of representations to be organized bottom-up in a time roughly linear in the depth of the network. This would allow much faster learning than supervised procedures which are generally very slow in networks with many layers of hidden units. We propose that a good objective for perceptual learning is to extract higher-order features that are coherent across time or space. This can be done by maximizing the explicit mutual information between parameters extracted from spatially or temporally adjacent parts of the input. Recent results obtained by Sue Becker show that this kind of objective function can be used to discover depth in random-dot stereograms. The approach can be applied to many other types of unsupervised perceptual learning. In particular, it should be able to discover the underlying three-dimensional shapes of objects when presented with an ensemble of two-dimensional images. Everyone is welcome. Refreshments served.