Influence of tonal and temporal expectations on chord processing and on completion judgments of chord sequences

The main regularities of the Western tonal system can be summarized as follows. The 12 notes of the chromatic scale are the basic elements of the system (C, C#, Db, D, D#/Eb, E, F, F#/Gb, G, G#/Ab, A, A#/Bb, B). Starting from each of these notes, sets of 7 notes define diatonic scales (e.g., C, D, E, F, G, A, B for C Major). Based on each diatonic note, chords (combinations of three notes, e.g., C-E-G for a C Major chord) are defined, which can be major, minor or diminished depending on the chosen notes. The diatonic scale with its associated chords defines keys (i.e., tonalities) that can be either major or minor. In each key, notes and chords have different musical functions, which define tonal-harmonic hierarchies. The first note of the scale (giving its name to the key) defines the tonic note (e.g., C) and the chord built on the first degree defines the tonic chord. Tonic note and tonic chord are the most referential musical events to which other events are perceived in relation. For notes, the tonic is followed in importance by the dominant, the mediant and then the last four notes of the scale. For chords, the chords built on the fourth and fifth degrees of the scale (i.e., referred to as subdominant and dominant respectively) are the most referential chords after the tonic. The other notes and chords act as less referential events. Notes and chords at the top of tonal-harmonic hierarchies are perceived as being more stable than other events. The differences in tonal stability influence music perception and memory (e.g., Hébert et al., 1995; Bigand & Pineau, 1997; Boltz, 1989a; Krumhansl & Kessler, 1982; Bigand, 1997; Krumhansl, 1979; Bharucha & Krumhansl, 1983).

For the purpose of the task, half of the target chords are rendered, for example, acoustically dissonant or out-of-tune. Participants have to indicate as fast and as accurately as possible whether the target is consonant or dissonant.

The three ending time conditions (early, late and on-time) were applied also for the irregular sequences in order to keep constant the temporal distance between the target and its preceding chord in comparison to the regular sequences.

Despite the strength of temporal manipulation in our study, this asymmetry can be interpreted in link with an expressive feature of musical performance, notably the decrease of tempo and dynamics at the end of musical sections or pieces (e.g., Todd, 1985). Delaying the ending allows insisting on the finality and clarifying the musical phrase structure. Because of listeners’ familiarity with performance, temporal deviations are probably more expected for delayed events than for anticipated ones.

Even when the task required to focus on a single event, the global context influenced chord processing for pitch and time dimensions: faster processing was observed for the harmonically related chords over less related chords and for regular sequences over irregular sequences (note that the penultimate chord was played at the same time points). Because of the local focus of the task, these influences of the more global context might occur in a rather automatic way.

It might be argued that the strength of pitch and time manipulations interacted with the task: Even if both manipulations can be judged explicitly, pitch manipulations were subtler than time manipulations; the integration of dimensions at different explicit levels would be possible for completion judgments, but not for speeded judgments in the priming task. However, let’s note that priming data obtained for sung musical sequences provided evidence for interactive influences in music and language processing despite different levels of explicit processing: the musical violation was as subtle as in the present material (tonic vs. subdominant), while the violation of semantic relations (target-prime) was relatively evident (The giraffe has a very long neck versus The giraffe has a very long foot) (Poulin-Charronat et al., 2005).