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PATTERN RECOGNITION & ZETA RETICULI

By Carl Sagan & Steven Soter

"The Zeta Reticuli Incident" is very provocative. It claims that a
map, allegedly shown on board a landed extraterrestrial spacecraft to
Betty Hill in 1961, later drawn by her from memory and published in
1966, corresponds well to similar maps of the closest stars resembling
the sun based on stellar positions in the 1969 Gliese Catalog of Nearby
Stars. The comparison maps were made by Marjorie Fish using a three
dimensional physical model and later by a group of Ohio State
University students using a presumably more accurate (i.e., less
subjective) computer generated projection. The argument rests on how
well the maps agree and on the statistical significance of the
comparison.

Figure 1 [not available here] show the Hill map and the Ohio State
computer map with connecting lines as given in the ASTRONOMY article.
The inclusion of these lines (said to represent trade or navigation
routes) to establish a resemblance between the maps is what a lawyer
would call "leading the witness". We could just as well have drawn
lines as in the bottom of Figure 1 to lead the other way. A less biased
comparison of the two data sets, without connecting lines as in Figure
2, shows little similarity. Any residual resemblance is enhanced by
there being the same number of points in each map, and can be accounted
for by the manner in which these points were selected.

The computer star map includes the sun and 14 stars selected from a
list of the 46 nearest stars similar to the sun, derived from the
Gliese catalog. It is not clear what criteria were used to select
precisely these 14 stars from the list, other than the desire to find a
resemblance to the Hill map. However, we can always pick and choose
from a large random data set some subset that resembles a preconceived
pattern. If we are free also to select the vantage point (from all
possible directions for viewing the projection of a three dimensional
pattern), it is a simple matter to optimize the desired resemblance. Of
course such a resemblance in the case of selection from a random set is
a contrivance -- an example of the statistical fallacy known as "the
enumeration of favorable circumstances".

The presence of such a fallacy in this case appears even more likely
when we examine the original Hill drawing, published in The Interrupted
Journey by John Fuller. In addition to the prominent points that Betty
Hill connected by lines, her map also includes a number of apparently
random dots scattered about -- evidently to represent the presence of
background stars but not meant to suggest actual positions. However,
three of these dots appear in the version of the Hill map used in the
comparison, while the others are absent. Thus some selection was made
even from the original Hill map, although not to the same extent as
from the Gliese catalog. This allow even greater freedom to contrive a
resemblance.

Finally, we lear from The Interrupted Journey that Betty Hill first
thought she saw a remarkable similarity between her UFO star map and a
map of the constellation Pegasus published in the New York Times in
1965 to show the position of the quasar CTA-102. How many star maps,
derived from the Gliese catalog or elsewhere, have been compared with
Betty Hill's before a supposed agreement was found? If we suppress
information on such comparisons we also overestimate the significance
of the result.

The argument on "The Zeta Reticuli Incident" demonstrates only that
if we set out to find a pattern correlation between two nearly random
data sets by selecting at will certain elements from each and ignoring
others, we will always be successful. The argument cannot serve even to
suggest a verification of the Hill story -- which in any case is well
known to be riddled with internal and external contradictions, and
which is amenable to interpretations which do not invoke
extraterrestrial intelligence. Those of us concerned with the
possibility of extraterrestrial intelligence must take care to demand
adequately rigorous standards of evidence. It is all too easy, as the
old Chinese proverb says, for the imprisoned maiden to mistake the
beating of her own heart for the hoof beats of her rescuer's horse.

Steven Soter is a research associate working under the advisement of
Carl Sagan, director of Cornell University's laboratory for Planetary
Studies.

Jerry
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