Figure 1.
Examples of triple and duple sequences.
Stimuli are event sequences with different rhythms composed of 24 temporal units that were 500 ms in duration, nine of which were silent units (open bars) and 15 of which were note units (dark bars). Each open bar represents a 500 ms silence. Each dark bar represents a note (pure tone/sinusoidal vibration) with a duration of 350 ms followed by 150 ms of silence. Triple sequences consisted of 8 notes (every third unit) in metrically important positions (M notes) and 7 notes in metrically unimportant positions (N notes). Duple sequences consisted of 6 M notes (every fourth unit) and 9 N notes. Arrows and dashed lines indicate M notes in the sequences.
Figure 2.
Statistics of the 374 triple and 331 duple sequences.
Figure 2A shows the number of successive notes in groups of 1, 2, 3, 4, and 5 occurring in the pool of sequences, indicating the same statistics for Triple and Duple sequences. Figure 2B shows the frequency of a note occurring at every 2nd, 3rd, and 4th unit in the pool of sequences, no difference between Triple and Duple sequences.
Table 1.
Test conditions for each experiment.
Figure 3.
Test trial of Triple sequence examples.
Each open bar represents a 500 ms silence. Each dark bar represents a note (pure tone/sinusoidal vibration) with a duration of 350 ms followed by 150 ms of silence. Larger dark in accented trials represent an amplitude accent, with 20 dB higher amplitude than regular dark notes. Exp. 1: unimodal trial, a whole triple sequence is assigned to either auditory or tactile modality. Ex. 2 and 3: bimodal trials, dark bars in channel 1 and channel 2 together compose a whole triple sequence. Exp. 4: bimodal trials, channel 1 contain a whole triple sequence, channel 2 contain additional Triple (Congruent) or Duple (Incongruent) M notes. For Exp. 2, 3, and 4, channel 1 notes sent to one modality and channel 2 notes sent to another modality. Channel 1 and 2 notes are assigned to either auditory and tactile modalities, or tactile and auditory modalities, respectively.
Figure 4.
Results of Experiment 1, unimodal meter perception performance.
(A) Performance for Triple-tending sequence. (B) Performance for Triple-tending sequence. Open bars represent unaccented condition, gray bars represent accented conditions. Error bars are Standard Error. (C) Solid line is unaccented metric note trials and dashed line is accented metric note trials.
Figure 5.
Results of Experiment 2, meter recognition performance in triple sequences for bimodal M/N split and M/N half split tasks.
(A) triple sequences tested in the M/N split task, (B) triple sequences tested in the M/N half-split task, (C) discriminability analysis of meter perception in the M/N split and M/N half-split tasks with Aud-C1/Tac-C2 condition, (D) discriminability analysis of meter perception in the M/N split and M/N half-split tasks with Tac-C1/Aud-C2 conditions. Open bars are results tested under unimodal condition. Hashed bars are results tested under bimodal condition. Error bars are standard error.
Figure 6.
Results of Experiment 3, meter recognition performance with triple sequences (A) and duple sequences (B).
(A) Correct responses to triple sequences. (B) Correct responses to duple sequences. Open bars: unaccented condition data. Gray bars: accented conditions. Hashed open bars: bimodal conditions. Hashed gray bars: bimodal accented conditions. Error bars are standard error. (C) Discriminability analysis of meter perception with Aud-C1/Tac-C2 condition; (D) Discriminability analysis of meter perception with Tac-C1/Aud-C2 condition. Open bars are unimodal unaccented control condition, hashed bars are bimodal unaccented condition; gray bars are unimodal accented control condition, and hashed gray bars are bimodal accented condition.
Figure 7.
Results of Experiment 4, meter recognition performance in triple sequences (A) and duple sequences (B).
Hashed bars show congruent condition and dotted bars show incongruent condition. Error bars are standard error.