How groove in music affects gait

Abstract

Rhythmic auditory stimulation (RAS) is a gait intervention in which gait-disordered patients synchronise footsteps to music or metronome cues. Musical ‘groove’, the tendency of music to induce movement, has previously been shown to be associated with faster gait, however, why groove affects gait remains unclear. One mechanism by which groove may affect gait is that of beat salience: music that is higher in groove has more salient musical beats, and higher beat salience might reduce the cognitive demands of perceiving the beat and synchronizing footsteps to it. If groove’s effects on gait are driven primarily by the impact of beat salience on cognitive demands, then groove’s effects might only be present in contexts in which it is relevant to reduce cognitive demands. Such contexts could include task parameters that increase cognitive demands (such as the requirement to synchronise to the beat), or individual differences that may make synchronisation more cognitively demanding. Here, we examined whether high beat salience can account for the effects of high-groove music on gait. First, we increased the beat salience of low-groove music to be similar to that of high-groove music by embedding metronome beats in low and high-groove music. We examined whether low-groove music with high beat salience elicited similar effects on gait as high-groove music. Second, we examined the effect of removing the requirement to synchronise footsteps to the beat (i.e., allowing participants to walk freely with the music), which is thought to remove the cognitive demand of synchronizing movements to the beat. We tested two populations thought to be sensitive to the cognitive demands of synchronisation, weak beat-perceivers and older adults. We found that increasing the beat salience of low-groove music increased stride velocity, but strides were still slower than with high-groove music. Similarly, removing the requirement to synchronise elicited faster, less variable gait, and reduced bias for stability, but high-groove music still elicited faster strides than low-groove music. These findings suggest that beat salience contributes to groove’s effect on gait, but it does not fully account for it. Despite reducing task difficulty by equalizing beat salience and removing the requirement to synchronise, high-groove music still elicited faster, less variable gait. Therefore, other properties of groove also appear to play a role in groove’s effect on gait.

Appendices

Appendix A

Stimulus selection

For a previous study in our lab, a database of 49 song clips was compiled. Eleven lab members rated these clips in terms of groove and familiarity on a 10-point Likert scale. Stimuli rated as greater than 5 on familiarity were discarded. Based on the ratings, a set of 10 songs were selected, five low groove, five high groove. The set of ten clips are listed below. Tempos for these ten clips were estimated by having four musically trained lab members manually tap to the beat on a USB-connected keyboard. The average tempo from the four lab members for each song was used. Participants walked with these songs with or without Met tones embedded.

Groove	Song Title	Artist	Album
High groove	Remember	ATB (André Tanneberger)	Dedicated
	bgmusic/20 Hilarious Jokes	Catherine Michael	20 Hilarious Jokes
	Conmigo Pachanga	Eddie Palmieri	Sugar Daddy
	Ritmo Caliente	Eddie Palmieri	Sugar Daddy
	Halo	Michael Salvatori	Halo: Original Soundtrack
Low groove	Primavera	Ludovico Einaudi	Divernire
	FL Studio—Acoustic Guitar, Violin	Farhan Khan	N/A (Single)
	Druid Fluid	Yo-Yo Ma, Edgar Meyer	Appalachia Waltz
	Bryter Layter	Nick Drake	Bryter Layter
	Farewell	Apocalyptica	Apocalyptica

Supplementary analyses

Effect of instructions to synchronise to music

Previously, we found that instructions to synchronise gait to music elicited slower, shorter, and more variable strides (Leow et al. 2018). To test if this replicated in this dataset, we compared conditions with/without instructions to synchronise, using a Synchronise (Synchronise, Freely walk) x Groove (Low Groove, High Groove) x Beat Salience (No Met Embedded, Met Embedded) ANOVA with between-subjects factors Age (Young, Older) and BP Ability (Weak Beat-perceivers, Strong Beat-perceivers) on gait parameters. We focussed here on the effect of synchronisation.

Gait speed parameters

When not instructed to synchronise to the beat (i.e., freely walking conditions), participants walked faster, taking more steps and longer strides, than in the synchronise conditions (see Fig. 1), as shown by significant main effects of synchronisation for stride velocity [F(1, 34) = 12.45, p = 0.001, partial η-squared = 0.27], stride time [F(1, 34) = 4.85, p = 0.03, partial η-squared = 0.12], and stride length [F(1, 34) = 13.96, p < 0.001, partial η- squared = 0.29]. Instructions to synchronise slowed strides in both strong and weak beat-perceivers, but more so in weak beat-perceivers, as shown by an Synchronise x BP Ability interaction for stride velocity [F(1, 34) = 4.90, p = 0.03, partial η-squared = 0.13] and stride time [F(1, 34) = 8.00, p = 0.008, partial η-squared = 0.19]. Gait was slowest when weak beat-perceivers were synchronizing to low-groove music, as shown by a significant Groove x Synchronise x BP Ability interaction for stride velocity [F(1, 34) = 6.89, p = 0.013, partial η-squared = 0.17] and stride time [F(1, 34) = 5.66, p = 0.02, partial η-squared = 0.14].

Gait variability

Stride velocity and stride length were more variable when instructed to synchronise to the beat than when freely walking with music (see Fig. 1), as shown by main effects of synchronisation for stride velocity variability [F(1,34) = 21.82, p < 0.01, partial η-squared = 0.39], stride length variability [F(1,34) = 37.01, p < 0.01, partial η-squared = 0.52]. The main effect for stride time variability missed significance [F(1,34) = 3.43, p = 0.07, partial η-squared = 0.09].

Bias for stability

Instructions to synchronise increased the bias for stability (see Fig. 2), as shown by main effects of synchronisation on stride width [F(1,34) = 10.93, p = 0.002, partial η-squared = 0.24], and double support time [F(1,34) = 4.48, p = 0.042, partial η-squared = 0.12]. For stride width, negative effects of synchronizing were most prominent with low-groove music, as shown by a significant Groove x Synchronise interaction [F(1, 34) = 4.29 p = 0.046, partial η-squared = 0.11], as instructions to synchronise increased stride width to a greater extent with low-groove music (0.157 [− 0.271, − 0.044], t = − 3.832, pbonf = 0.002), than with high-groove music (mean difference between freely walking and synchronise conditions = − 0.096 [− 0.209, 0.018], t = − 2.33, pbonf = 0.107).

In summary, when walking with music, instructions to synchronise elicited slower, shorter, and more variable strides than walking without instructions to synchronise.