Fig. 50.1
Example stimuli from each experiment. Only triple sequences are shown here. Each empty bar represents a 500 ms silence unit. Each colored bar represents a note unit, a pure tone/sinusoidal vibration at the pitch level of A4 (220 Hz) and duration at 350 ms followed by a 150 ms silence
3 Results
3.1 Experiment 1: Meter Perception via Unimodal Stimulation
The mean correct response for unaccented triple sequences through auditory and tactile stimuli alone was 82 and 75 %, respectively. Adding amplitude cues increased performance to 90 and 84 % for auditory and tactile stimuli, respectively. Results for duple perception showed the same trend. The comparison of d ′ values for the two test conditions shows that accented cues may be weighted more heavily in auditory than in tactile modality.
3.2 Experiment 2: Bimodal Integration in Meter Perception
In the M/N split condition, there was little, if any, metric information within a single channel with performance at chance level (50 %) for triple sequences and performance slightly above chance (60 %) for duple sequences. When the sequences were presented bimodally, subjects were able to perceive meter clearly for both triple meter and duple meter. For triple sequences, the bimodal enhancement was 19 % when the red channel was auditory and 39 % when the red channel was tactile. For duple sequences, bimodal enhancement was 7 % for auditory and 22 % for tactile conditions. The results from the M/N split condition show that meter is integrated across touch and audition and that M notes play a larger role when presented through the auditory system.
The second condition (M/N half split) used a less structured distribution of notes with the M and N notes split evenly between the two channels. Subjects did not perceive triple meter in the unimodal conditions, with performance at 43 and 45 % for the auditory and tactile modalities, respectively, confirming that meter information was not present within a single channel. In the bimodal condition, correct response to triple sequences increased to 59 and 63 %, respectively. The comparison of d ′ between unimodal and bimodal conditions showed that adding the remaining notes from the other channel produced reliable recognition of meter pattern. The results provide evidence of cross-modal grouping of disassembled meter cues from information presented in auditory and tactile modalities to form an integrated meter perception.
3.3 Experiment 3: Asymmetry Between Auditory and Tactile Stimulation in Meter Perception
In experiment 3, the red channel contained all of the N notes and half of the M notes with the blue channel containing the other half of the M notes. This asymmetric distribution allowed us to observe modality-dependent characteristics of meter perception. Unaccented unimodal control conditions produced chance-level performance for triple perception and slightly above chance-level performance for duple perception. The presence of the other half of the M notes in the blue channel from auditory inputs significantly increased meter perception performance for the unimodal tactile condition by 20 % for triple perception and 23 % for duple perception. However, the presence of the other half of the M notes from the tactile modality did not significantly change subjects’ performance. These results indicate that the contribution of metric cues in meter perception is modality dependent and that the auditory modality obviously plays a bigger role than the tactile modality. Accented metric cues significantly enhanced the discriminability of meter when the red channel was the auditory input, and auditory input significantly enhanced the discriminability of meter when the red channel was from the tactile input. The results show that the roles of auditory and tactile stimulation in meter perception are asymmetric with auditory input dominating.
3.4 Experiment 4: Interference Between Auditory and Tactile Channels in Meter Perception
In the congruent condition, while the meter cues were the same for both channels, performance was high, with correct responses to triple sequences at 83 and 96 % for auditory and tactile red channels, respectively, and 68 and 93 % for duple sequences. In the incongruent condition, performance for triple sequences dropped to 70 and 11 % for auditory and tactile red channels, respectively, and 54 and 2 % for duple sequences.
4 Discussion
Music is generally considered to be an auditory experience. However, it is often accompanied by other sensory stimuli (e.g., proprioceptive, vestibular stimuli) and motor actions. One of the most prominent sensory modalities that contribute to music perception is the tactile modality. As we know, mechanical vibrations to the skin allow musicians to “feel” vibrations in their instruments when playing music. This “feeling” of music can also been seen in listeners tapping their hands and feet to the rhythm.
In the present study, we tested young adults with some musical training in a meter discrimination task. Subjects can perceive the implied meter patterns from auditory or tactile sequences with ambiguous rhythms (unaccented condition) at an average accuracy rate of about 82 % (auditory) and 75 %. This performance is slightly better than what Hannon and Johnson found in their auditory studies, which could be explained by our subjects having musical training and being older than those tested in the Hannon et al. studies (Hannon and Johnson 2005). We showed that unimodal tactile meter perception behaves like auditory meter perception and that performance increases significantly when accent cues are added to key metrical notes. These results demonstrate that meter can be perceived through passive touch and that tactile and auditory meter perception share similar characteristics.
In the next set of experiments, we tested the degree to which auditory and tactile inputs are integrated in processing meter. If, for example, the sensory systems process information independently, then presenting the inputs bimodally should not affect meter perception. We found that meter information is extracted from combined auditory and tactile input. Performance rose from chance with unimodal input when there were no meter cues to 70–90 % with bimodal input. It should be noted that subjects performed all of the experiments without feedback, demonstrating that auditory-tactile integration for meter perception is an automatic process. Previous studies have shown that sensory grouping could not occur across sensory modalities (for review, see Spence and Chen 2012). Results from the present study provide evidence of cross-modal grouping of disassembled meter information from auditory and tactile modalities to form an integrated meter perception.
We further explored whether auditory or tactile input was dominant in meter perception by altering the balance between the auditory and tactile input of metric cues. We found that the presence of metrically important notes from the auditory modality has a significant larger influence on meter perception than those from the tactile modality, indicating that auditory input plays a dominant role in music perception. We also found that accent cues enhanced meter perception more strongly when presented from the auditory modality. This dominance could be due to the level of stimulation that we used in the current study. It is not clear if the dominance of audition over touch would persist if a larger area of the body and gut which is full of Pacinian corpuscles were activated by tactile input. Thus, intensity cues cannot be ruled out as playing a role in the dominance of audition over touch in our study. Other possibilities need to be also considered, as previous studies on audiovisual interactions have shown auditory dominance for the processing of rhythmic temporal stimuli (Guttman et al. 2005), and auditory inputs seem to be the least susceptible to influences from other sensory inputs in the perception of temporal events (Bresciani et al. 2008).
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
