Figure 3 provides a sample of normalized displacement and normalized velocity time series for one participant of each handedness group in the 2:1 and 1:2 conditions.
Cycle duration ratio
Cycle duration ratios are displayed in Fig. 4a. The analysis of cycle duration ratio indicated no significant main effects of Handedness, F(1,22) = 0.21, p = 0.65, and Task, F(1,22) = 0.14, p = 0.71. The interaction Handedness X Task, F(1,22) = 1.46, p = 0.24, also failed to reach significance.
Cycle duration and cycle duration variability
Cycle duration and cycle duration variability are displayed in Fig. 4b, c. The analysis of the cycle duration indicated a Task X Hand interaction, F(1,22) = 593.74, p < 0.01, ηp2 = 0.96. Simple main effect analysis for Task across Hand indicated significantly longer cycle durations for the right wrist compared to the left wrist in the 2:1 task, F(1,22) = 948.28, p < 0.01, ηp2 = 0.97, and shorter cycle durations for the right wrist compared to the left wrist in the 1:2 task, F(1,22) = 270.78, p < 0.01, ηp2 = 0.93. The interactions Handedness X Task, F(1,22) = 2.25, p = 0.15, Handedness X Hand, F(1,22) = 1.75, p = 0.20, and Handedness X Task X Hand, F(1,22) = 0.55, p = 0.46, failed to reach significance. In addition, the main effects of Task, F(1,22) = 0.07, p = 0.78, Hand, F(1,22) = 0.01, p = 0.99, and Handedness, F(1,22) = 0.71, p = 0.41, were not significant. This indicated that longer cycle durations were observable when moving the lower than the higher frequency wrist.
However, the analysis of the cycle duration variability indicated a Task X Hand interaction, F(1,22) = 80.43, p < 0.01, ηp2 = 0.78. The simple main effect analysis for Task across Hand indicated significantly higher cycle duration variability for the right wrist compared to the left wrist in the 2:1 task, F(1,22) = 15.59, p < 0.01, ηp2 = 0.41, and lower cycle duration variability for the right wrist compared to the left wrist in the 1:2 task, F(1,22) = 11.03, p < 0.01, ηp2 = 0.34. The other two-way interactions Handedness X Task, F(1,22) = 3.65, p > 0.05, Handedness X Hand, F(1,22) = 3.06, p = 0.09, and the three-way interaction Handedness X Task X Hand, F(1,22) = 0.05, p = 0.82, were not significant. The main effects of Task, F(1,22) = 0.09, p = 0.77, Hand, F(1,22) = 1.41, p = 0.25, and Handedness, F(1,22) = 0.65, p = 0.43, failed to reach significance. As for cycle duration, higher cycle duration variability was shown when moving the lower than the higher frequency wrist.
Harmonicity
Harmonicity values are displayed in Fig. 4d. The analysis of harmonicity indicated a Task X Hand interaction, F(1,22) = 127.88, p < 0.01, ηp2 = 0.85. Simple main effect analysis for Task across Hand indicated that the faster moving wrist had higher H-values compared to the slower moving wrist regardless of whether the participant performed the 2:1, F(1,22) = 93.28, p < 0.01, ηp2 = 0.81, or the 1:2 task, F(1,22) = 88.1, p < 0.01, ηp2 = 0.80. The interactions Handedness X Task, F(1,22) = 4.12, p = 0.06, Handedness X Hand, F(1,22) = 1.97, p = 0.17, and Handedness X Task X Hand, F(1,22) = 0.6, p = 0.81, failed to reach significance. Furthermore, the main effects of Task, F(1,22) = 0.146, p > 0.76, Hand, F(1,22) = 2.17, p = 0.16, and Handedness, F(1,22) = 0.53, p = 0.48, were not significant.