The processing of pitch and temporal information in relational memory for melodies

A series of experiments investigate the roles of relational coding and expectancy in memory for melodies. The focus on memory for melodies was motivated by an argument that research on the evolutionary psychology of music cognition would be improved by further research in this area. Melody length and the use of transposition were identified in a literature review as experimental variables with the potential to shed light on the cognitive mechanisms in memory for melodies; similarly, pitch interval magnitude (PIM), melodic contour, metre, and pulse were identified as musical attributes that appear to be processed by memory for melodies. It was concluded that neither previous models of verbal short term memory (vSTM) nor previous models of memory for melodies are unable to satisfactorily explain current findings on memory for melodies. The model of relational memory for melodies that is developed here aims to explain findings from the memory for melodies literature. This model emphasises the relationship between: a) perceptual processes – specifically, a relational coding mechanism which encodes pitch and temporal information in a relational form; b) a short term store; and c) the redintegration of memory traces using schematic and veridical expectancies. The relational coding mechanism, which focuses on pitch and temporal accents (c.f., Jones, 1993), is assumed to be responsible for the salience of contour direction and note length, while the expectancy processes are assumed to be more responsible for the salience of increases in PIM or deviations from the temporal grid. Using a melody discrimination task, with key transposition within-pairs, in which melody length was manipulated, Experiments 1a, 1b, and 2 investigated the assumption that contour would be more reliant on the relational coding mechanism and PIM would be more reliant on expectancy processes. Experiment 1a confirmed this hypothesis using 8 and 16 note folk melodies. Experiment 1b used the same stimuli as Experiment 1a, except that the within-pair order was reversed in order to reduce the influence of expectancy processes. As expected, while contour was still salient under these conditions, PIM was not. Experiment 2 was similar to Experiment 1b, except that it avoided using the original melodies in same trials in order to specifically reduce the influence of veridical expectancy processes. This led to a floor effect. Overall, the results support the explanation of pitch processing in memory for melodies in the model. Experiments 3 and 4 investigated the assumption in the model that temporal processing in memory for melodies was reliant on the relational coding mechanism. Experiment 3 found that, with key transposition within-pairs, there was little difference between pulse alterations (which deviate more from the temporal grid) and metre alterations (which lengthen the note more) in short melodies, but that pulse alterations were more salient than metre alterations in long melodies. Experiment 4 showed that, with tempo transposition within-pairs, metre alterations were more salient than pulse alterations in short melodies, but that there was no difference in salience in long melodies. That metre alterations are more salient than pulse alterations in Experiment 4 strongly suggests that there is relational coding of temporal information, and that this relational coding uses note length to determine the presence of accents, as the model predicts. Experiments 5a and 5b, using a Garner interference task, transposition within-pairs, and manipulations of melody length, investigated the hypothesis derived from the model that pitch and temporal information would be integrated in the relational coding mechanism. Experiment 5b demonstrated an effect of Garner interference from pitch alterations on the discrimination of temporal alterations; Experiment 5a found a weaker effect of Garner interference from pitch alterations on the discrimination of temporal alterations. The presence of Garner interference in these tasks when there was transposition within melody pairs suggests that pitch and temporal information are integrated in the relational coding mechanism, as predicted in the model. Seven experiments therefore provide support for the assumption that a relational coding mechanism and LTM expectancies play a role in the discrimination of melodies. This has implications for other areas of research in music cognition. Firstly, theories of the evolution of music must be able to explain why features of these processing mechanisms could have evolved. Secondly, research into acquired amusia should have a greater focus on differences between perceptual, cognitive, and LTM processing. Thirdly, research into similarities between music processing and language processing would be improved by further research using PIM as a variable