Distinct roles of cognitive and sensory information in musical expectancy
Expectation is crucial for our enjoyment of music, yet the underlying generative mechanism remains contested. While sensory–acoustic models derive predictions based on the short-term auditory input alone, cognitive models assume the use of abstract knowledge of music structure acquired over the long-term. To evaluate these two contrasting mechanisms, we compared simulations from computational models of musical expectancy against subjective surprise ratings of chords sampled from US Billboard pop songs in musicians and non-musicians. Bayesian model comparison revealed that probabilistic knowledge of music structure and auditory short-term memory both explained unique behavioural variance without mediation. However, probabilistic knowledge accounted for nearly four times as much variance in musicians, and over twice as much in non-musicians. Incorporating both probabilistic knowledge and auditory short-term memory together furthermore improved predictive accuracy over the individual models. Our findings thus motivate an alternative to the current debate by emphasising the distinct, albeit complementary, roles of cognitive and sensory information in forming expectations during music-listening in humans.