brain sexual dimorphism

Professor Robert Thornton (031RTHOR@MUSE.ARTS.WITS.AC.ZA)
Sun, 19 Feb 1995 13:24:05 -0500

I have not been following the thread on tool use, neurological sexual
dimorphism and other things since i am just plain too busy, but i did
want to introduce some interesting 'introspective' data that has
relevance to both of htese threads.
Odd though it may seem, I see differently out of each eye. In a
sense this gives me two, often quite different views of the world. I
don't know if there are others who experience this, but my queries
with various optomotrists and opthalmologists over my life time
suggests to me that it is rare. In fact, I have not met any eye-
doctors (to use a shorter term) who can understand what I am talking
about when I describe the phenomonon t them.
Briefly, this is what I see: First of all, I see a
different section of the spectrum with each eye. With the left, I
see a much 'warmer' spectrum. I can not see very deep violet with
the left eye. It simply disappears. I can see it with my right eye,
so I know its there. This is not a problem for the most part, but is
obvious to me when I look at certain shades of stained glass, for
instance, where it looks deep blue/violet with one eye, and simply
brown to the other eye. Also, with certain deep blue/violet lights
used to mark police stations in the US, for instance in Princeton
where I was recently, I perceive these lights are being 'there' or
not 'there' depending on which eye I use.
Secondly, I can only read with my left eye. I can see letters,
edges, large patterns and shapes with the right eye, but I can not
order the experience into meaning, that is, I can not read but only
see. This is clearly a neurological phenomenon, since it does not
change with any refraction or other modification of light source,
reading material,etc. There are two possibilities that I have
considered for this. As a child, I was quite severely dyslexic, and
it was discovered that I was ambliopic ('squint' -- the two eyes did
not work together, which was not surprising to me since they saw two
different 'worlds'). I have considered that it may be that only one
eye 'learned' to read. But despite efforts (patching the left ete,
lenses, etc.) the right eye never 'learned ' to read. The other
hypothesis that I have entertained is
that the neurological pathways were damaged at birth due to hypoxia
that damaged these areas selectively and not, somehow, my general
'intelligence', which turned out to be rather good, despite the
damned eyes.
So, what does this prove? Well, for one thing, it seems to me to
show that pattern recognition and the association of semantic content
with pattern (as in reading, as well as in tool classification, and
by extension, tool use) is partly neurologically mediated. All I have
to do is query my two differnt eyes for this conclusion to be
supported, for me, every day. It also suggests that there is a
laterality to the recognition of patterns and to ordering of
percetpions (as in ordering of letters in a word, or the facets of the
complex shape, both of which I can not do with my right eye).
Ifmy experience is neurological, and its seems to me that it must be
since it has been stable for all my conscious life, then it means
that I see the world as two different people might see it (one eye at
a time), but I see it within one head and one cognitive apparatus.
In effct, I have been able to compensate and adjust for the fact that
(I believe) there is actually only one world out there, and that my
perception of it differs both from that of others, and from one eye
to the other. This has never caused me any problems, apart from the
reading problem-- which put me in the 'slow steam' at school until
the 4th grade, and in the 'fast stream' after it was corrected.
Again, two rather different experiences of the social world, before
and after dyslexia. As we know, the mind can compensate for quite
radically different inputs and still somehow 'see' the same thing.

All of this probably explains why I am an anthropologist,
incidentally. Well, I have rabbited on too long, but it seemed to me
that this neurological experience might have some interesting
implications for discussions currently on the list. I have not yet
adequately explained these phenomena to myself, but I thought some of
you might enjoy this bit of data from a 'native' of a peculiar
neurological 'place'.

=====Professor Robert Thornton, Department of Social Anthropology====
University of the Witwatersrand, PO Wits, 2050 Johannesburg
South Africa
Office tel. : (011) 716-2900
Secretary, fax and answering machine: (011) 716-2766
Home tel: (011) 646-2578
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