## 3 Results
### Initial Superimposition of Acoustic Startle and Touch Displacement
COP\({}_{\text{AP}}\), center of pressure anterior–posterior; TA, tibialis anterior; SOL, soleus; AD, anterior deltoid; PD, posterior deltoid; SCM, sternocleidomastoid; OO, orbicularis oculi. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline  & \multicolumn{6}{c}{**Stimulus**} & \multicolumn{6}{c}{**Statistical Results**} \\ \hline A & D\({}_{1}\) & D\({}_{8-10}\) & C\({}_{1}\) & C\({}_{S}\) & S\({}_{1}\) & S\({}_{S}\) & \(n\) & Main Effect & Tukey’s HSD (\(p<0.05\)) \\ \hline
**Mechanical** & & & & & & & & \\ \(\Delta\)COP\({}_{\rm AP}\) (mm) & 8.1 (3.4) & 0.5 (0.3) & \(-\)0.2 (1.6) & 2.3 (1.1) & 0.6 (0.9) & 1.1 (1.2) & 8 & 3.38 (\(p=0.014\)) & D\({}_{1}>\) D\({}_{8-10}\) \\ \(\Delta\)Elbow (deg) & \(-\)3.2 (1.4) & 2.6 (0.6) & 7.5 (1.9) & 3.6 (1.0) & \(-\)0.3 (0.3) & 0.0 (0.2) & 7 & 11.6 (\(p=0.000\)) & D\({}_{1}<\) D\({}_{8-10}\) \\
**EMG (\%MVC)** & & & & & & & & \\ TA & 7.6 (3.3) & 0.2 (0.2) & 21.9 (8.5) & 8.0 (3.1) & 2.0 (1.1) & 2.4 (1.1) & 8 & 6.31 (\(p=0.000\)) & D\({}_{8-10}<\) C\({}_{1}\), C\({}_{1}>\) C\({}_{S}\) \\ AD & 0.7 (0.3) & 3.9 (0.7) & 18.4 (5.7) & 8.9 (3.2) & 1.9 (1.5) & 1.8 (1.6) & 8 & 7.24 (\(p=0.000\)) & D\({}_{8-10}<\) C\({}_{1}\) \\ SCM & \(-\)0.2 (0.2) & \(-\)0.2 (0.1) & 42.1 (15.0) & 15.0 (6.0) & 9.4 (4.4) & 6.0 (3.5) & 8 & 6.74 (\(p=0.000\)) & D\({}_{8-10}<\) C\({}_{1}\), C\({}_{1}>\) C\({}_{S}\) \\ CO & 1.8 (1.5) & 0.7 (0.4) & 21.7 (8.4) & 30.7 (5.7) & 26.2 (6.4) & 22.7 (7.2) & 8 & 9.71 (\(p=0.000\)) & D\({}_{8-10}<\) C\({}_{1}\) \\
**Stimulus** & & & & & & & & & \\ \(\Delta\)COP\({}_{\rm AP}\) (mm) & 5.5 (1.2) & 0.2 (1.0) & 2.8 (0.9) & \(-\)0.6 (0.4) & 0.3 (1.0) & 1.8 (0.9) & 8 & 7.79 (\(p=0.000\)) & D\({}_{1}>\) D\({}_{8-10}\) \\ \(\Delta\)Elbow (deg) & \(-\)1.8 (0.3) & 2.7 (0.3) & 0.5 (0.3) & \(-\)0.2 (0.1) & 4.2 (0.7) & 3.2 (0.4) & 5 & 29.4 (\(p=0.000\)) & D\({}_{1}<\) D\({}_{8-10}\), D\({}_{8-10}>\) S\({}_{1}\), S\({}_{S}<\) C\({}_{1}\) \\
**EMG (\%MVC)** & & & & & & & & \\ TA & 9.3 (4.8) & 0.4 (0.3) & 1.1 (0.5) & 1.6 (1.4) & 2.6 (1.4) & 0.2 (0.2) & 8 & 2.50 (\(p=0.049\)) \\ AD & 1.7 (0.4) & 4.0 (0.7) & 1.1 (0.7) & 1.2 (0.5) & 4.4 (1.8) & 3.8 (0.9) & 8 & 4.12 (\(p=0.005\)) & S\({}_{S}<\) C\({}_{1}\) \\ SCM & \(-\)0.1 (0.2) & 0.6 (0.8) & 20.5 (6.1) & 6.1 (2.7) & 5.9 (0.6) & 3.2 (1.6) & 6 & 6.95 (\(p=0.000\)) & D\({}_{8-10}<\) S\({}_{1}\), S\({}_{1}>\) S\({}_{S}\) \\ CO & 0.1 (0.3) & 0.8 (0.7) & 13.7 (4.4) & 11.4 (4.7) & 16.2 (3.4) & 16.0 (3.9) & 8 & 12.1 (\(p=0.000\)) & D\({}_{8-10}<\) S\({}_{1}\) \\ \hline \hline \end{tabular} Values are means (SE), COP\({}_{\rm AP}\), center of pressure anterior-posterior TA, tibialis anterior; AD, anterior delibed; SCM, stereodidemmatoid; OO, obticularis oculi; D, touch displacement; S, start; C, combined; MVC, maximum voluntary contraction. Statistical results are \(F\) statistics and \(P\) values. [PERSON]’s HSD applied to adjacent points in sequence only.  
\end{table} 
Table 1: Change in COP\({}_{\rm AP}\) position and elbow angle, and normalized muscle response amplitudes. Figure 5B displays the averaged data for the cohort of participants who received the COMBINED stimuli initially, followed by DISPLACEMENT and then STARTLE alone. The COMBINED stimuli data for this cohort are qualitatively similar to what is shown in Figure 5A. Of note, the COMBINED stimuli evoked a pronounced forward sway (Trial 1 = 21.6 \(\pm\) 7.9 mm) that decreased with repeated trials (Trials 8-10 = \(4.5\pm 2.4\) mm), concomitantly with a pronounced initial elbow flexion (Trial 1 = \(19.5\pm 4.0^{\circ}\)) that progressively decreased until no response at the elbow was apparent (Trials 8-10 = \(0.3\pm 0.9^{\circ}\) of flexion on average). Subsequently, the data resulting from DISPLACEMENT and STARTLE are similar to the comparable stimuli of Figure 5A. A complete report of the descriptive statistics and the result of the associated ANOVAs is provided in Table 2B. Figure 5: Trial-by-trial mean (SE) mechanical and muscle response amplitudes for participants who habituated to the COMBINED stimuli initially.