Saturday, December 10, 2011

[Yasmin_discussions] Fwd: [Yasmin_an] Synaesthesia in Chimpanzees


fascinating post by sean day which states:

Thus, we are called upon, here, to re-asses our definitions of "the
senses" and "modes", and, thus, also, "cross-modal".

here is the abstract of the article Sean Day pointed us to


Humans share implicit preferences for certain cross-sensory
combinations; for example, they consistently associate higher-pitched
sounds with lighter colors, smaller size, and spikier shapes. In the
condition of synesthesia, people may experience such cross-modal
correspondences to a perceptual degree (e.g., literally seeing
sounds). So far, no study has addressed the question whether nonhuman
animals share cross-modal correspondences as well. To establish the
evolutionary origins of cross-modal mappings, we tested whether
chimpanzees (Pan troglodytes) also associate higher pitch with higher
luminance. Thirty-three humans and six chimpanzees were required to
classify black and white squares according to their color while
hearing irrelevant background sounds that were either high-pitched or
low-pitched. Both species performed better when the background sound
was congruent (high-pitched for white, low-pitched for black) than
when it was incongruent (low-pitched for white, high-pitched for
black). An inherent tendency to pair high pitch with high luminance
hence evolved before the human lineage split from that of chimpanzees.
Rather than being a culturally learned or a linguistic phenomenon,
this mapping constitutes a basic feature of the primate sensory

---------- Forwarded message ----------
From: Day,Sean <>
Date: Sat, Dec 10, 2011 at 6:13 PM
Subject: Re: [Yasmin_an] Synaesthesia in Chimpanzees

A recent article regarding cross-modal correspondences and synesthesia
has appeared in PNAS:

Ludwig, Vera U., Ikuma Adachi, and Tetsuro Matsuzawa.  2011.
"Visuoauditory mappings between high luminance and high pitch are
shared by chimpanzees (Pan troglodytes) and humans."  PNAS;

I would like to state the following:

The last common ancestor of chimpanzees and humans (CHLCA) existed
somewhere between 7 and 10 million years ago (mya).  So, we can push
cross-modal correspondences in our ancestry back to at least 7 mya,
and note that not only was it persistent in the genera leading up to
modern-day species of Pan, but, apparently, would also have appeared
in (at least) genera Sahelanthropus, Ardipithecus, and
Austraolopithecus, on the way to genus Homo.  Which implies also that
cross-modal correspondences would have occurred amongst Homo sapiens'
previous companion species erectus, Denisovans, Neanderthals, and

I will posit the following: "Synesthesia", by force of its basic
definition, must be the minority circumstance for a given species.
"Synesthesia" means an (atypical) combining of what are,
statistically, most commonly un-combined sensory perceptions.

Now, if, as Ludwig et al. 2011 suggests, cross-modal correspondences
can be traced back in our line to at least 7 mya with the CHLCA, and,
as Marks, Cytowic, Ramachandran, and many other synesthesia
researchers have pointed out, is so pervasive in modern-day humans -
then that is not "synesthesia".  It is also not "cross-modal

Rather, that is how the human senses most typically - statistically - work.

Thus, we are called upon, here, to re-asses our definitions of "the
senses" and "modes", and, thus, also, "cross-modal".

Again, for something to be "cross-modal", that implies that there are,
indeed, two separate modes, and that a correspondence between them
would, given the odds, be more unlikely.  If, however, such
correspondences are the more common event - as, apparently, they are
for humans regarding, e.g., luminance and (sound) pitch (frequency) -
then that is how our perception most commonly works, and we need to
re-evaluate what we now increasingly see are outdated paradigms
regarding "the senses" and "perceptual modes".

Much of what is currently being labeled "cross-modal correspondence"
is not.  For something to be a cross-modal correspondence, that, too,
would have to be the less likely event.

I will note that Ludwig et al. do, indeed, carefully distinguish
between cross-modal correspondences and synesthesia, seeing them as
separate but potentially related things.

Sean A. Day, Ph.D.
Dept. of Behavior and Soc. Sciences
Trident Technical College
Charleston, SC  29423  USA

(843) 574-6539

President, American Synesthesia Association

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