Looking at some of the material Bob posted about
Occidental, I have to admit that I had some curiosity
about the language but find it off-putting.  I
generally find that the auxlang proposals that are
less naturalistic in their approach than Interlingua
tend to have a distinctly repulsive effect, though
Interlingua doesn't, and curiously, Esperanto also

When reading Occidental, for instance, words like
"naturalmen" and "presc" and "ultim" look and feel
inappropriate, because in the context they look like
they should be "naturalmente" and "presque" and
"ultima".  Not unrelated is the objection I brought up
with James Chandler's Medilingua, which has
constructions like "Ila vide io" where Interlingua
would have "Illa me vide."  Yet I wouldn't be bothered
by "naturale" or "preskaux" or "fina" in Esperanto.

So here's a hypothesis.  Semi-naturalistic auxlangs
suffer from the "Uncanny Valley" effect.  Basically: 
a robot with less than 70% resemblance to a human
being will elicit a positive response, and a robot
with more than 90% resemblance will also have a
positive response.  But between these poles, there is
actually a very strong negative response.  It's the
same with how closely an auxlang resembles natural
languages.  Occidental, to me, is clearly in the
"uncanny valley," while Esperanto and Interlingua are
on opposite sides of it.  Esperanto is mostly
schematic, so you don't expect it to behave
"naturally"; Interlingua derives its words and rules
naturally, so it lacks artificial or "forced"

Now, this effect is mostly there for speakers of
Western European languages, and it's part of why
things like "did" and "sal" in Novial also grate to
me.  And there are even things in Interlingua or
Esperanto that venture into "uncanny valley"
territory, such as the "mismatched" adjective-noun
pairs of Esperanto ("bona patro") or the plural
present indicative of the Interlingua copula ("illes
esse," often switched to "illes son"); but Occidental
is square in the middle, being simultaneously too
artificial and too natural for its own good.

There's a good Wikipedia article on the idea of the
Uncanny Valley:


 - Wayne