edb@akgua.UUCP (E.D. Brooks [Emily]) (06/25/84)
Perfect pitch was the subject of much discussion a little while
ago in this newsgroup so I thought this article might be of
interest.
****************Beginning of Article*****************************
From the June 1984 *Scientific American* column "Science and the
Citizen" subtitled "A Note on Perfect Pitch":
Perfect pitch, the ability to identify a tone without hearing a
second tone for comparison, is an intriguing phenomenon
neurologically. Introspection and guessing are generally poor
guides to the workings of the brain, but in this case it is hard
to resist the hypothesis that the brain of a person with perfect
pitch includes (as other brains do not) a mental representation
of standard tones in permanent storage. A person lacking such
representation can have only relative pitch; he can listen to
tones in succession and try to compare one tone with the next to
establish the interval.
The available evidence supports the hypothesis. For example,
people with perfect pitch are better than people with relative
pitch at identifying intervals if several seconds pass between
the sounding of the first tone and the second. The difference in
performance is to be expected, because the "working", or short-
term, memory in which a tone is stored for comparison with
subsequent tones maintains the storage for a few seconds at the
most. New evidence goes further. In confirming the hypothesis
about perfect pitch it also tends to confirm a hypothesis about
the large-scale electrical activity of the brain.
The evidence was collected by Mark Klein, Michael G. H. Coles and
Emanuel Donchin of the University of Illinois at Urbana-
Champaigne, who tested 14 students of music there. The results
are reported in *Science*. Seven of the 14 described themselves
as having perfect pitch, and they tended to be better at
identifying tones. When they did make errors, they named the
pitch correctly, but "they assigned it to a higher or lower
octave than that of the actual stimulus".
Each subject was given "oddball tests". In a test the subject
saw two visual stimuli (the letter *H* or the letter *S*) or
heard two auditory stimuli (a tone of 1,000 hertz or a tone of
1,100 hertz) in random alternation. In each test one of the
stimuli was rarer than the other: it was presented on only a
fifth of the trials. The subject was asked to count the rarer
stimuli. Meanwhile a set of scalp electrodes was recording the
electrical activity of the brain. The results over many trials
were averaged to minimize the "noise" in the recordings; in this
way a characteristic waveform called the event-related potential
emerges. It can include a positive peak, maximal in the parietal
lobe at the crown of the brain, roughly 300 milliseconds after
the stimulus is presented. The peak is known as a P300. It is
thought to signify (in the language of cognitive science) that
the brain is updating the contents of working memory.
All 14 subjects "counted all rare events with equal accuracy",
but the electrical recordings revealed some remarkable
differences. The seven subjects who said they did not have
perfect pitch showed "standard" event-related potentials for both
the visual and the auditory oddball tests. The potentials
included a P300. Evidently the brain was holding the memory of a
stimulus over the brief time required to compare it with a
subsequent stimulus.
The seven subjects who said they did have perfect pitch tended to
show standard event-related potentials only on the visual test.
On the auditory test the P300 was notably smaller. Indeed, the
smallest P300's were measured in the brain of the subjects who
had done best on the test of their perfect pitch. Two things
seem to be confirmed: a person with perfect pitch does not rely
on working memory to identify a tone, and the brain's updating of
working memory truly is signaled by a P300.
****************End of Article***********************************
So now you know...you folks with perfect pitch really ARE different!
Emily Brooks ...{ihnp4!}akgua!edb