An experiment was conducted to examine the application of the optimal-complexity model to musical aesthetics. The model seeks to explain the relationship between the complexity of music and the listener's affective response. In this thesis the underlying harmonic structure of 7-tone melodies was systematically manipulated according to the rules of Western harmony.
Three sets of melodic sequences were created. Two groups of listeners selected on the basis of musical training rated single presentations of sequences on a 6-point scale of either "pleasingness" or "complexity." Effects of repetition were also investigated by having sequences repeat 10 times in a row with listeners rating sequences after each repetition. The results indicated a positive monotonic relationship between "pleasingness" ratings and harmonic structure. This relationship was mirrored by "complexity" ratings which decreased linearly with structure. Differences between the sets occurred for "pleasingness" ratings but not for "complexity" ratings. Repetition effects varied according to the level of harmonic structure. Results suggest that ability of the model to predict affective responses to music may be limited to wide stimulus ranges.