The wood and the trees - The Visualization of Spatial Social Structure - page 239

voting patterns in Britain in relation to just five variables - the electorate
(head size), house price (thin face for low, fat for high), employment (smile),
election turnout (nose size) and industrial structure (large low eyes for younger
industries). 13 The colour of the face can then represent the actual voting
patterns, when the faces are arranged as a group on the constituency cartogram
(Figure 8.8). It is also well worth looking at the faces with the colour taken out
of them (Figure 8.9). The computer code used to draw these faces is reproduced
in the Appendix to this topic.
The images of smiling and frowning heads were initially intended to be a
tongue-in-cheek extension of Chernoff faces, faces amalgamated to the level of
crowds. Nevertheless, the inner-city/outer-city and north/south divides in many
aspects, as well as voting, can clearly be seen (Figures 8.10 and 8.11). The
difficulty of drawing precise lines between the regions and around cities is clear.
What is more, specific outliers can be identified, which do not fit in (just as
before with arrows that did not go with the flow). Variables that appear to be
unrelated to the rest of the picture can be identified. Complex three- or four-
way interactions, where certain levels of some variables apparently combine to
produce a particular effect, can also be identified.
The use of the population cartogram developed here, as the spatial base for
these faces, has particular advantages. None of the faces overlap to obscure each
other and they are all, by their size, drawn in proportion to their importance
based on the numbers of people they represent. It may well be that glyphs have
not been much used in spatial images before, because of the dire problems of
spatial congestion, which the use of population cartograms in place of land area
maps overcomes. It would be difficult, for instance, to use faces in place of the
circles that overlap and cluster on the electoral triangle, although it may produce
an interesting picture to compare with the crowd on the cartogram.
Strong local relations in space are perhaps the clearest message formed by
the images. Sharp divisions are also immediately apparent, as are more gradual
changes. 14 The faces can also be used to show that the changes over time in
the variables might be contributory to the changes over time in voting. Thus
the expressions become places' reactions to a changing situation, their colours
perhaps indicating some of the electoral results of those changes (Figures 8.12
and 8.13).
Chernoff faces are contentious for some of the same reasons that they are
so useful. People's reactions to faces are much stronger than to more neutral
objects, which are claimed to depict the information more objectively. Facial
features are inevitably interpreted as depicting joy or sadness, concern or apathy
13 Research has found that even slight changes in expression are perceived: 'This latter finding
suggests that extreme caricature like faces are not crucial in obtaining good performance' (Jacob,
Egeth and Bevin, 1976, p.193).
14 Faces can provide an alternative to the use of aggregate indices in studying multivariate spatial
change: 'The over-riding impression of the changes taking place in local economies since 1981 is
clearly of the division between north and south' (Champion and Green, 1989, p. 84).