Testing the stability of 'Default' motor and auditory-perceptual rhythms-A replication failure dataset

Abstract

Several studies have found that the motor rhythms that individuals produce spontaneously, for example during finger tapping, clapping or walking, are also rated perceptually as 'very comfortable' to listen to. This motivated proposal of the Preferred Period Hypothesis, suggesting that individuals have a characteristic preferred rhythm, that generalizes across perception and production. However, some of the experimental procedures used previously raise two methodological concerns: First, in many of these studies, the rhythms used for assessment of participants' Perceptual Preferred Tempo (PPT) were tailored specifically around each participant's personal Spontaneous Motor Tempo (SMT). This may have biased results toward the central rhythm used, artificially increasing the similarity between spontaneous motor and auditory perceptual preferences. Second, a key prediction of the Preferred Period Hypothesis is that the same default rhythms are repeatedly found within-subject. However, measures of consistency are seldom reported, and increased within-subject variability has sometimes been used to exclude participants. The current study was an attempt to replicate reports of a correspondence between motor and perceptual rhythms, and closely followed previous experimental protocols by conducting three tasks: SMT was evaluated by instructing participants to tap 'at their most comfortable rate'; PPT was assessed by asking participants to rate a 10 different rhythms according to how 'comfortable' they were; and motor-replication of rhythms was assessed using a Synchronization-Continuation task, over a wide range of rhythms. However, in contrast to previous studies, for all participants we use the same 10 perceptual rhythms in both the PPT and Synchronization-Continuation task, irrespective of their SMT. Moreover, we assessed and report measures of within- and between-trial consistency, in order to evaluate whether participants gave similar rating and produced similar motor rhythms across multiple sessions throughout the experiment. The data presented here fail to show any correlation between motor and perceptual preferences, nor do they support improved synchronization-continuation performance near an individual's so-called SMT or PPT. Rather, they demonstrate substantial within-subject variability in the spontaneous motor rhythms produced across repeated sessions, as well as their subjective rating of perceived rhythms. This report accompanies our article "Spontaneous and Stimulus-Driven Rhythmic Behaviors in ADHD Adults and Controls"[1], and provided motivation and insight for modifying the procedures used for SMT and PPT evaluation, and their interpretation.

Keywords: Auditory perception; Auditory-Motor interactions; Finger tapping; Motor rhythms; Synchronization.

Fig. 1

Spontaneous Motor Tapping results A) Median SMT values (top) and consistency across sessions (bottom) for individual participants, in ascending order of mean SMT. The horizontal dashed line indicates the cutoff of CV_{across_sessions} = 0.25, used in previous studies to exclude participants who had inconsistent SMTs across sessions. B) Distribution of CV_{within_trial} CV (top), CV_{within_session} (middle) and CV_{across_sessions} (bottom) across all participants. The dashed black line represents the group median and the gray line indicates the cutoff of CV_{across_sessions} = 0.25, shown also in A.

Fig. 2

Preferred Auditory Perceptual Tempo results. A) Example from a single participant of the procedure to estimate PPT from the average gradings of 10 different rhythms (black dots) on a 10-point scale from −5 (too slow) to +5 (too fast), with 0 being “most comfortable”. The dashed gray line indicates the best polynomial fit, and the crossing-point indicated by a gray asterisk is the estimated PPT. B) Distribution of PPT values (top) and consistency (CV, bottom) for all participants, in ascending order of mean PPT.

Fig. 3

Relationship between SMT and PPT. Linear regression analysis testing the correspondence between the median SMT and PPT values obtained for each participant black dots. Neither the regular regression (dashed thick line) or robust regression (solid line; outliers marked in dashed circles) yielded significant results, indicating no correlation between the two measures. The thin dashed thin line is the diagonal unity line.

Fig. 4

Synchronization and Continuation results. A) Mean tapping precision error for all tempi during synchronization (left panel) and continuation (right panel) task. The main effect of tempo was significant only in the continuation tasks. B) same as A) for CV_{within_trial}, indicating degree of tapping isochrony. Here there was a main effect of tempo during the synchronization but not continuation task. Error bars depict SEM.

Fig. 5

Continuation tapping precision-error for all participants. Subplots are ordered according to the degree of variability in precision errors across tempi. Each participant's median SMT and PPT are indicated by the cyan and magenta lines, respectively (the precision-error at SMT/PPT was estimated based on linear interpolation of the two nearest tempi, and is marked with a circle of the same color).

Fig. 6

Precision error as a function of the distance from SMT / PPT: A) Continuation precision error estimated at each participants’ median SMT and PPT. Box plots depict the median and the 25/75th percentiles. Outliers are indicated by the + sign, (values are considered outliers if they are > 1.5 times the interquartile range from the top or bottom of the box). B) Precision error across tempi aligned relative to each participant's individual SMT and PPT. No apparent U-shape is observed, which would have suggested that performance is better near ones SMT/PPT. C) Example of the linear regression procedure applied to one example participant. A linear fit was performed separately for tempi faster (left) and slower (right) than the participants SMT, and slope values β were extracted for each side. D) Distribution of the estimated β slope values across all participants, showed separately for the analyses conducted relative to the SMT (left) and PPT (right). Box plots depict the group-median 25/75th percentiles. Outliers are indicated by the + sign. Precision error increased consistently for rhythms slower than both the SMT and PPT, but no consistent relationship was found for faster rhythms. This pattern is inconsistent with the notion that performance is optimal near one's SMT/PPT.

Fig. 7

Experimental design. Top: The three tasks performed during the experiment. Bottom: Time line of performing each task and repetition across sessions.

Fig. 8

Analysis of Spontaneous Tapping Behavior - example from one participant. Top: Tapping ITIs in single trials, across all three sessions of the SMT task (three trials per session). Bottom: The central (median, mean) and consistency (CV) metrics derived from tapping ITIs, within and across session, to characterize different aspects of spontaneous tapping.