Expectancy

Music unfolds over time, and listeners continuously form expectations about forthcoming events (such as tones, chords, percussive sounds, and rests). These ongoing musical expectations are sometimes violated and sometimes fulfilled, giving rise to a complex and dynamic pattern of tension and relaxation that contributes greatly to an aesthetic experience. Expectancy is one of the most well researched and theorized mechanisms thought to underlie the link between musical structure and affective response. When researchers first started investigating this connection, the guiding assumption was that violations of expectancy (such as surprise) engendered affect. Over the ensuing decades, more nuanced accounts were developed in which various stages and aspects of expectancy-based engagement were understood to be relevant to felt experience.

Various methodologies have been devised to investigate expectancy. In one approach, listeners are presented with a musical context and asked to sing or perform a continuation. In a variant of this approach, they are presented with a musical context and subsequently asked to rate the quality of different continuations to it. Both of these techniques are limited to uncovering explicit expectations—expectations listeners know they are having. But implicit expectations—expectations that listeners aren't consciously aware of having—can also play an important role in the generation of musical affect. To investigate these, researchers have used priming studies, which measure changes in reaction time related to the degree to which particular events were expected, and event-related potentials, which measure changes in electrical activity via electrodes on the scalp, identifying particular changes that relate to expectancy violation. Changes in electrodermal activity and heart rate have also been used to identify moments of musical surprise.

In the 1950s, Leonard Meyer made the initial link between surprise and musical affect, following John Dewey's conflict theory of emotions. According to this theory, emotions arise when a tendency to respond is inhibited. For example, a smoker reaching into his pocket for a pack of cigarettes might only experience an emotional charge when he realizes that the pack is empty. Many musical patterns carry implications about how they will continue. Just as the man experienced an emotion when his expectation was violated, music listeners might experience emotions when these musical implications are violated.

A classic example is the deceptive cadence. Normally, a tonic chord follows the dominant at the end of a phrase. But sometimes the dominant progresses to a different chord instead, the submediant. Even though the submediant involves just one note that's different than the tonic, it's enough [Page 437]to generate a surprise that translates as a subjective impression of affective intensity. This example underscores one of the aspects of expectancy that was most exciting to researchers of music and emotion: its ability to explain emotional percepts that vary dynamically across the listening experience. The example also illustrates one of the main challenges to expectancy-based accounts of musical emotion: Ludwig Wittgenstein's puzzle. If one has heard a piece many times and knows that a deceptive cadence happens at a particular moment, why does that move to the submediant continue to retain its affective power? This puzzle has been addressed by separating veridical expectations (expectations about what comes next in a particular piece of music) from schematic expectations (expectations about what generally happens in a particular style). Even when a deceptive cadence fulfills veridical expectations, it might continue to violate schematic ones.

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