UC Genetics of Absolute Pitch Study
Posted by Xeno on April 6, 2010
What is absolute pitch?
Absolute pitch, commonly referred to as perfect pitch, is an intriguing cognitive trait involved in music perception and is defined as the ability to identify the pitch of a musical tone without an external reference pitch. To be considered an absolute pitch possessor, an individual must have the ability to identify pitches accurately and instantaneously.
The primary goal of this study is to discover the genes that are involved in the development of absolute pitch (perfect pitch). This investigation will allow us to better understand the interplay of genetics and musical training in the development of this cognitive trait. These findings may also be applicable to other traits, such as language ability, and, more broadly, to neurodevelopment.
The goals of this website are to inform the public about the University of California Genetics of Absolute Pitch Study and to recruit individuals to take part in this study. This study is being conducted in the laboratory of Dr. Jane Gitschier at the University of California, San Francisco and has been approved by the UCSF Committee on Human Research.
Our findings to date
Nature vs. nurture
Based the absolute pitch survey and auditory test data we have collected to date, we learned that the majority of individuals with absolute pitch began formal musical training before age 7. This finding supports the hypothesis that early musical training may be necessary for the development of absolute pitch. However, early musical training alone is not sufficient for development of absolute pitch, because many individuals with musical training initiated before age 7 do not possess absolute pitch.
We also observed that absolute pitch aggregates in families, indicating a role for genetic components in its development. Indeed we found that a sibling (with early musical training) of an absolute pitch possessor is about 15 times more likely to possess absolute pitch than is another individual with early musical training but with no family history of absolute pitch.
Together, these observations implicate a genetic predisposition to the development of absolute pitch, which, when coupled with an environmental stimulus such as early musical training, can give rise to the perceptual trait. The development of our pitch-naming test and these initial results were reported in two papers in the American Journal of Human Genetics (1998 and 2000).
These findings encouraged us to develop the project further and to establish an efficient mechanism for recruiting additional subjects and their families into a genetic study. We have now employed our website to recruit thousands of individuals, both absolute pitch and non-absolute pitch possessors, into our study.
Absolute pitch perception as a distinct trait
Based on the results from 2213 subjects who completed our web-based survey and pitch-naming test within a 3-year time span, we learned that absolute pitch (perfect pitch) ability is a discrete perceptual trait, not simply the one end of a continuous “normal” distribution of pitch ability.
The figure below shows a “scatterplot” of the distribution of scores from both the piano tone test (Y-axis) and pure tone test (X-axis) for these subjects. Each dot represents the pair of scores from at least one individual. The area of the dot is proportional to the number of people who scored identically at those piano and pure tone scores.
The scores cluster into two groups. One group is centered at the low range of scores. These scores lie within a box that defines the range of scores expected by random guessing. The other group clusters at the opposite end of the figure, near or at the maximum score of 36 for both the pure and piano tone tests. (Although each test involves 40 tones, we do not score 4 tones, in either test, that lie at the extreme ends of the frequency range.) The vertical line shows the cut-off point for designation of “AP1″ in our study. The probability of scoring above this cut-off by chance alone is about one in a trillion!
(Reproduced with permission from Athos et al. 2007. Click to view full article.)
This finding shows that for the population who has entered our study, most people score either very high or very low. A fewer number of subjects score in between these two ranges, and they generally score better on the piano tone test than the pure tone test. We suspect that these individuals have learned to identify some pitches and employ relative pitch to make calculated guesses in pitch-naming.
Changes in pitch perception with age
Absolute pitch possessors sometimes indicate a frustration with their pitch perception as they get older. They sometimes tell us that it goes “off”.
The study data corroborate these anecdotal experiences. None of our subjects past the age of 51 identified all of the tones perfectly, unlike their younger counterparts. We discovered that pitch perception tends to go sharp as subjects age. Some subjects name notes consistently a semi-tone sharp by middle-age, while others name tones a full tone sharp as they enter their 60′s. We suspect that there is some property in the ear that changes as people age to cause this perceptual shift. Age-related changes are common, such as the need for reading glasses and hearing loss. It is interesting that this change can be observed and quantified only in people who have absolute pitch!
Distortion in pitch perception
By analyzing the vast archive of perceptual data accumulated over the Web, we found something unexpected: absolute pitch possessors tend to err on G# far more than any other tone, an error that occurs only on pure tones. Most often, G# pure tones are misidentified as “A” tones. We hypothesize that this phenomenon reflects the use of A as the universal tuning pitch in Western music. Since the actual frequency of A used in tuning varies widely, from A415 in early music to A446 in some orchestras, we suspect that absolute pitch possessors accommodate a wide range of frequencies in their naming of A. We further speculate that this accommodation is not used in piano tones, since pianos are generally tuned to A440. This phenomenon is reminiscent of a property referred to as “perceptual magnet” in language acquisition.
The above findings on pitch perception have been published in the Proceedings of the National Academies of Science – click here for the article.
No wonder I haven’t seen much improvement after over a year of trying to acquire absolute pitch. If a human brain can do this, mine can do it. That’s my attitude. I’m going to keep trying even if it takes another ten years.