What Can Infants Tell Us About Meter Perception? Evidence For Innate Perceptual Constraints

14 Feb

Developmental scientists have begun to record how exposure to culturally-specific music in infancy might influence music perception in child and adulthood. Previous studies found that young infants are sensitive to both simple and moderately-complex meters up until 6-months of age . From here, cultural-specific biases begin to arise — a process casually referred to as music enculturation.

Erin Hannon, Gaye Soley, and Rachel Levine, wanted to see if there are innate perceptual constraints related to meter perception and ratio complexity. Musical stimuli were created from one Bulgarian folk melody using simple (2:1), complex (3:2), or highly-complex (7:4) metrical ratios. Thus, the same melody was appropriated to three different meters: 4/4, 7/8, and 15/8. Additionally, the melody was transposed to 4 different keys and arranged to to multiple instrumentation in order to sustain infant attention. 78 infants, ages 5 or 7 months, were presented with either a simple, complex, and highly-complex melody during a habituation phase. After successful habituation, infants were presented with a series of familiar melodies, or a disrupted melodies that contained an extra 200 ms gap. The researchers expected the younger infants to notice the melodies with the gap (a disruption of the overall meter) on the simple and complex conditions but not the older infants.

The results were consistent with previous studies on infant meter perception. The 5 month group were able to detect the disruptions in the simple and moderately complex conditions. The 7 month group however, began to express a cultural-specific bias to simple ratios and were unable to detect disruptions in the moderately or highly complex conditions. The important finding, however, was that the younger infants were unable to identify the disrupted melodies in the highly complex (7:4) condition. Thus, there appears to be perceptual constraints on meter perception correlated with ratio complexity. What might be the cause of this bias? The researchers theorize perhaps simple ratios are easier on the ears (processed more efficiently in the brain, perhaps) or that listeners tend to appropriate complex ratios into an over-arching hierarchy of a less-complex ratio.

Hannon, E. E., Soley, G., & Levine, R. S. (2011). Constraints on infants’ music rhythm perception: Effects of interval ratio complexity and enculturation. Developmental Science, 1-8.

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