Discussion

Completion judgments showed that moderately experienced listeners were sensitive to the change of tonal degree induced by the transposition of the melodies’ first part: melodies ending on the mediant were judged as more complete than melodies ending on the leading tone. This finding obtained with highly controlled material corroborates melodic context effects previously reported with completion or tension judgments (Bigand, 1997; Boltz, 1989a; Hébert, Peretz, & Gagnon, 1995; Schmuckler, 1989).

The main goal of Experiment 1 was to extend the tonal priming data obtained for tonic versus subdominant for chords (Bigand & Pineau, 1997; Bigand et al., 2003) and melodies (Marmel et al., In Press) to a pair of tonal degrees that does not involve the tonic. The combined analysis of Experiment 1 showed faster response times for mediants over leading tones. This finding suggests that tonal expectations influence target processing also for the present choice of tonal degrees, even if the priming effects were weaker than those found in studies using the tonic (see General Discussion).

An influence of the timbre task was observed, with facilitated processing only for the target timbres that were more continuous with the context timbre. In Experiment 1a, an interactive pattern between tonal relatedness and target timbre was observed. In Experiment 1b, the observed difference in response times was stronger for Timbre B. Even if here the two target timbres were carefully chosen to sound similar to the context timbre, distances between musical timbres in perceptual timbre spaces (see Hajda, Kendall, Carterette, & Harshberger, 1997, for a review) suggest a stronger similarity between flute (the prime timbre) and clarinet (Timbre B) than between flute and oboe (Timbre A) (Kendall, Carterette, & Hajda, 1999; Wedin & Goude, 1972). Our data thus suggest the importance of acoustic continuity in the sounding of the melodies. A discontinuity in timbre may induce strategic biases and/or it may lead to perceive the target as belonging to a different auditory stream than the prime context. Notably, changes in harmonic spectrum contribute to segregate an event from the current stream (Bregman, 1990). The more dissimilar target timbre may pop-out from the melodic context, leading targets to be perceived as “deviant” stimuli, which would be less (or not) integrated in the context. The stronger influence of timbre in Experiment 1a than Experiment 1b might be linked to the use of only one target timbre different from the context. Leading tones played with this different timbre mismatched with the context in two dimensions (timbre and pitch) and might thus have been easier to identify, resulting in the reversal of the priming effect.

Similar influences of timbre choices have been reported in priming experiments that contrasted tonic and subdominant in chord sequences (Tillmann et al., 2006) and melodies (Marmel, Tillmann, & Delbé, submitted). These experiments revealed significant priming effects despite the influence of timbre, leading to stronger effects for the more continuously sounding timbre. Since the contrast in tonal stability investigated in our study was subtler than the contrast between tonic and subdominant, the influence of sound continuity might be more detrimental to the priming effect. Another task providing an experimental condition with a continuously sounding target is the intonation task (used in harmonic priming experiments) that can be adapted for melodies. This task showed a tonal context effect between tonic and subdominant tones (Marmel et al., In Press) that was larger than the tonal context effect observed with a timbre task (Marmel et al., submitted). Experiment 2 used this intonation task in order to strengthen the influence of tonal expectations on target tones (i.e., mediants versus leading tones).