Developing Intelligence

To what extent is music like language? Previously, I’ve reviewed how music and language share semantic characteristics, at least insofar as similar scalp electrical activity follows incongruent musical passages as follows incongruent words. But is it also possible that music has grammar, just like language?

In the context of language, ungrammatical words are often accompanied by a sharp rise in scalp electrical activity, around 600 milliseconds after the grammatical violation. This is known as the P600, or sometimes as the syntactic positive shift (SPS). Because this scalp electrical component shows sensitivity to grammatical violations, some suggest that it indexes the function of a grammar-specific module. However, the P600 can also be observed in response to violations of number and gender agreement, phrase structure, verb tense, and even case, suggesting the response is much more general than would be expected from a correlate of a “grammar module” (if one were to exist).

In their 1998 JoCN paper, Patel et al. show that the P600 can distinguish between chord changes that are appropriate to western music versus those that violate more typical chord progressions. To demonstrate this, the authors compared the ERP responses of subjects to phrases like “an old idea” when embedded in three different types of sentences: those that were grammatically OK (“Some of the senators had promoted an old idea of justice”) grammatically poor (“Some of the senators endorsed promoted an old idea of justice.”) and those that were flat-out ungrammatical (“Some of the senators endorsed the promoted an old idea of justice.”)

They then did the same thing, except with music: the authors constructed musical passages based on the “circle of fifths” and inserted notes that were either concordant or discordant with those passages. The inserted notes were never “wrong” in and of themselves (i.e., they were not mistuned or unusual); they simply did not seem to match the harmonic progressions of the musical passage.

The recordings of scalp electrical activity in response to these stimuli revealed that ungrammatical phrases and discordant notes alike were associated with a P600 component, when compared with grammatical phrases and concordant notes respectively. The positive shifts of scalp electrical activity in response to structurally/grammatical incongruous stimuli were statistically indistinguishable from one another, at least in terms of their amplitudes and scalp distributions. So, music seems to have a form of implicit rule structure very much like grammar in language, to the extent that similar neural generators may be involved in processing anomalies across those modalities!

Patel et al note that this similarity is even more striking considering that P600s were evoked from musical passages by manipulating the identity of the target, whereas they were evoked from ungrammatical phrases by manipulating the stimuli preceeding the target.

The authors conclude that the P600 may reflect “knowledge-based structural integration” rather than the activity of a grammar-specific cognitive module. I’m not entirely sure what this means, and they don’t fully explain, but it is important to note that the P600 may be a very late version of the P300 response. The P300 is thought to represent attentional reorienting or the updating of working memory as a result of context violations. Unfortunately, they do not discuss why the P600 differs from the N400 response, also shown to be sensitive to words that are incongruent with the preceeding context (whether verbal or musical), but only when the violations have to do with mismatches in meaning.

Related Posts:
Meaning from Melody: Music as Language
Can music convey meaning in the same way as language?
Neuroscience of Music
Is there musical syntax like language syntax?

Comments

  1. #1 mick grierson
    March 5, 2007

    Awesome post Chris.

    I guess that “knowledge based structural integration” suggests that they think this response is to do with context violations. I guess it’s certainly easier to demonstrate that than to say it has something to do with ‘hard wired grammar’.

    However, if you take the chomskian view regarding the existance of a linguistic ‘module’, then the idea of time-based pattern structures (such as music and film etc.) engaging and manipulating some sort of logic based ‘meaning-perception’ module seems kind of attractive…

  2. #2 Chris Chatham
    March 5, 2007

    Thanks Mick – yeah, I definitely buy the context violation. But given that people invoke the same thing for the N400 effect (which responds only to semantic violations), I definitely agree that it’s tempting to fall back on a Chomskian “rule-violation-detector.” [shudder] :)

  3. #3 Jonathan Vos Post
    March 5, 2007

    Wonderful thread.

    But “circle of fifths” is specific to “Western” music. What do, say, Balinese people’s brains do, given that they are used to the microtonalities of Gamelan? Or people from cultures with other scales with base other than 12, where “circle of fifths” is unique because 5 is the only number relatively prime to 12 and less than half of 12 (Group Theory).

    And given some studies that show “dissonnance” is psychophysically maximum at about a third of a tone, in both humans and chimpanzees, what do chimps’ brains do in this experimental set-up?