Friday, December 14, 2012

Peculiarities of Absolute Pitch

Topical Reference:
Takeuchi, A. H. & Hulse, S. H. (1991). Absolute-Pitch Judgments of Black- and White-Key Pitches. Music Perception, 1, 27-46.


This is an influential paper on Absolute Pitch (AP), the ability to accurately label pitches without the aid of an external reference. It confirms a known attribute of this ability, which is the fact that AP possessors (APers) seem to identify the pitches of black piano keys less quickly and accurately than the pitches of white-keys. Experiments on AP accuracy at the time involved identifying pitches using a motor-response such as pressing a key on a piano keyboard. This may have created a motor-response bias or a labeling-response bias, where the APers choose more white-key labels as responses, accounting for the raised white-key accuracy. These researchers decided to use a task that eliminated both of these biases by presenting the pitches auditorily while simultaneous presenting pitch-labels visually. The APers would then respond with "Same" or "Different" on a computer keyboard. All APers had to meet the criteria of responding with 90% correctness within a semitone to be included in the analysis; meaning errors of a semitone were counted as correct.

The APers responded to black-key pitches significantly more slowly and significantly less accurately than for white-key pitches. Response times were also significantly slower for visual presentations of black-key labels in comparison to white-key labels.

The first possible explanation given was that the difference in perceptual and memory-retrieval processing between black- and white-key may be due to how these pitches occur in the music literature. The second was that APers encode primarily the white-key pitches and interpolate black-keys from neighboring white-keys, adding an internal comparison step for black-keys while identifying white-keys with sheer pitch memory.

It would appear that the black- and white-key difference in accuracy and reaction time is confirmed to be an aspect of AP. In this case, labeling white-keys would involve a single step, which would imply that true AP only exists for white-keys. Black-keys however would use multiple steps, where a white-key label is associated to the pitch then modified. This processing would first determine whether the pitch is a white-key and if not, add a sharp or flat to the label of whatever white-key pitch was reflexively recalled.

In this sense, the labeling system and pitch categorization process become conceptually the same. It seems that in AP, black-keys are categorized as if they were modified white-keys. Ironically, this is exactly how black-keys are labeled in Western musical notation, as modified white-keys! Thus, the label and notation might affect the way musical pitches are perceived. In essence, the label seems to effect the perception of what is being labeled. Truly, categorization is an odd thing.

This attribute of AP is not the only thing that makes AP far from deserving the title 'perfect.' The fact that semitone errors abound in AP seems to even further demystify the ability (Levitin & Rogers, 2005). The practice of not counting errors that are only a semitone off in AP experiments is common. AP actually has a range of accuracy gradients, where high scores and quick reaction times are correlated (Atho et al., 2007; Bermudez & Zatorre, 2009).

What is particularly ingenious about this test was its apparatus. They created a kind of AP Stroop test. This type of test presents multiple categorizations at the same time. One example involves presenting the word "blue" in a red font and vice versa (Ex. Blue, Red, etc.), then having the subject simply name the color in question. Reaction time effects were seen in these experiments as well (Stroop, 1935).

AP is of interest to me primarily because it is evidence of a stable link between internal representations and musical sound, which is extremely rare and measurable (Baggaley, 1974; Lockhead & Byrd, 1981). In particular, it is remarkable because it gives rise to evidence of some kind of memory retrieval for auditory information that is an order magnitude greater than chance, which for categorizing musical pitches is 8.3% (Zatorre, 2003). APers are able to consistently accurately label the pitch of specific sound sources presumably due to an internal template of pitches, encoded into the long-term memory during a possible critical period for AP acquisition (Russo et al., 2003; Ward & Burns, 1978).

Questions of whether AP involves motor-representations and other cross-modal phenomena have been fostered by these kinds of studies. How this ability is actually acquired is still unknown but the majority of APers seem to report early-age fixed pitch instrument training, particularly on the piano (Parncutt & Levitin, 2001; Takeuchi & Hulse, 1991). APers also identify the pitches of a piano faster than that of other timbres, which shows some link between AP and piano training in my opinion (Miyazaki, 1989).

This ability has long been misunderstood. Though many might associate AP with musical genius or giftedness, calling it 'Perfect Pitch' would be a misnomer in light of the limitations of AP that experimental psychology has demonstrated. Nevertheless, it remains enigmatic due its rareness and novelty.

Athos, E. A., Levinson, B., Kistler, A., Zemansky, J., Bostrom, A., Freimer, N., Gitschier, J. (2007). Dichotomy and perceptual distortions in absolute pitch ability. Proceedings of the National Academy of Sciences, 104, 14795-14800.

Baggaley, J. (1974). Measurement of absolute pitch. Psychology of Music, 2, 11-17.

Bermudez, P. & Zatorre, R. (2009). A distribution of absolute pitch ability as revealed by computerized testing. Music Perception, 27, 89-101.

Lockhead, G. R. & Byrd, R. (1981). Practically perfect pitch. Journal of the Acoustical Society of America, 70, 387-389)

Miyazaki, K. (1989). Absolute pitch identification: Effects of timbre and pitch region. Music Perception, 7, 1-14.

Parncutt, R. & Levitin, D. J. (2001). Absolute pitch. In Sadie (Eds.), The New Grove.

Russo, F. A., Windell, D. L., Cuddy, L. L. (2003). Learning the "special note": Evidence for a critical period for absolute pitch acquisition. Music Perception, 119-127.

Schlaug, G., Norton, A., Overy, K., & Winner, E. (2005). Effects of music training on the child's brain and cognitive development. Annals of the New York Academy of Sciences, 1060, 219-230.

Stroop, J. R. (1935). Studies of interference in serial verbal reactions. Journal of Experimental Psychology, 18, 643–662.

Zatorre, R. J. (2003). Absolute pitch: A model for understanding the influence of genes and development on neural and cognitive function. Nature Neuroscience, 6, 692-695.

1 comment:

Matt Tip said...

Interesting study indeed. This is quite an eye-opoening read on how to obtain absolute pitch: