Context Propagation Based on Membership Feedback
Kohei Inoue and Kiichi Urahama
Faculty of Visual Communication Design, Kyushu Institute of Design, Fukuoka, Japan 815-8540
SUMMARY
The authors discuss a simple model for pattern dis-
crimination incorporating temporal or spatial context by
feedback of the membership values output at the high-rank
winner-take-all (WTA) neurons to the lower-rank pattern
selection response neurons. They propose a teacherless
training method based on maximum likelihood. First, for
the temporal context, they study examples with the feed-
back of discrimination effect of a first moment to the next
moment, and demonstrate that clustering is performed by
proximity of presentation moments rather than by the pat-
tern similarity. Next, for the spatial context, they show that
a similar pattern recognition method can be applied to
spatial smoothing of image patterns. © 2000 Scripta Tech-
nica, Syst Comp Jpn, 32(1): 4552, 2001
Key words: Context-dependence; membership
feedback; topologically invariant pattern recognition;
teacherless training.
1. Introduction
Human pattern recognition is affected by the tempo-
ral context and spatial context. Sakai and Miyashita [1]
conducted tests of union tasks on charts to study how they
are affected by the temporal context, and demonstrated that
the charts pattern pairing is formed only by proximity of
presentation moments, rather than by pattern similarity. It
was discovered that such union memory can be represented
by two types of neurons: neurons for encoding and neurons
for recollection. The neurons for recollection are stimulated
only by the context information even if there is no pattern
input. Then, the response of the low-order vision neurons
is also affected by stimuli outside of the reception field,
which demonstrates a spatial context effect [2]. The fill-in
phenomenon shows that response due to surrounding con-
text information is generated even at locations without
input. Based on this physiological and psychological infor-
mation, researchers have tried modeling of learning for
deformation-invariant pattern recognition by using tempo-
ral context [35].
This article relates to simple modeling of the context
effect. The spatial context propagates both by long-distance
lateral connections between neurons and by feedback con-
nections. In this study, we shall discuss exclusively the
feedback effect for both temporal and spatial context. In
other words, it is assumed that in pattern recognition de-
vices the context information is supplied in top-down fash-
ion, to enrich the bottom-up information from the input
patterns. If all of the information is somehow captured in
one mode, it can be considered a variation of the multimo-
dal pattern recognition (with two modes: top-down and
bottom-up). The authors [6] had previously proposed a
teacherless method of learning for close-neighborhood
multimodal pattern recognition. Based on that previously
introduced method, we propose in the current study a
pattern recognition and learning method that involves con-
text. First, we discuss cases relating to the temporal context,
when discrimination effects of the previous moment are fed
back to the next moment. It will be shown that clustering is
based on proximity of presentation rather than on similarity
of patterns, and simple applications to topologically invari-
ant pattern recognition will be demonstrated. Next, it will
be shown for the spatial context that the same pattern
© 2000 Scripta Technica
Systems and Computers in Japan, Vol. 32, No. 1, 2001
Translated from Denshi Joho Tsushin Gakkai Ronbunshi, Vol. J82-D-II, No. 3, March 1999, pp. 494500
45