## 2 Materials and Methods
### Procedure  
Testing took place following each child's prescribed clinical gait assessment. Children were asked to walk at a self-selected (preferred) speed along an 8 m walkway, stepping into two successive targets on the floor (Figure 1). Targets were created using black electrical tape affixed flush to the floor. Target position for each participant was determined during three practice overground gait trials, so that the participant's 4 th step landed in target 1 and 7 th step landed in target 2. No other guidance was provided. The targets were rectangular with dimensions normalized to 150% of participant's foot length and foot width. Therefore, the position of targets on the ground, the relative distance between targets, and the size of targets changed between participants. Target size was chosen to reflect scenarios in activities of daily living where precise foot placement is required to navigate the environment. Participants walked to a cone beyond target 2 to ensure steady walking speed through the targets. Five trials were captured, and all children successfully stepped in to both targets during each trial. Children with CP did not wear any orthotics or use any form of walking aid, and 11 children (3 TD children, 5 children with diplegic CP, and 3 children with hemiplegic CP) wore glasses when completing the trials.  
Participants wore tight-fitting clothing (e.g., Lycra or swimsuit). Twenty-nine retroreflective markers were placed according to a modified [PERSON] model [25], with additional markers placed on both acromion processes, xyphoid process, T10, and a headband comprising four markers. Children completed this study in bare feet with one additional marker placed centrally on the dorsum of each foot (determined as 50% of measured foot length and width), representing the foot center. A four-marker cluster positioned on the laboratory floor was used to define virtual landmarks for each corner of both targets using a digitizing wand (C-Motion, Germantown, MD, USA). Kinematic data were captured at 340 Hz using 12 Smart DX cameras (BTS Bioengineering, Milan, Italy).  
\begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Diplegic CP Group** & **Hemiplegic CP Group** & **TD Group** \\  & **(_n_ = 9)** & **(_n_ = 9)** & **(_n_ = 8)** \\ \hline Sex (m/f) & 6/3 & 5/4 & 5/3 \\ Age (yrs) & 10.2 (2.5) & 10.6 (2.8) & 10.9 (2.4) \\ Height (m) & 1.43 (0.13) & 1.43 (0.15) & 1.31 (0.48) \\ Mass (kg) & 40.02 (15.02) & 38.00 (10.01) & 35.86 (13.65) \\ CMFCS level (I/I) & 6/3 & 8/0 * & - \\ Affected side (L/R) & & 4/5 & - \\ Visual acuity (LogMAR) & 0.10 (0.19) + & \(-\)0.04 (0.22) & \(-\)0.21 (0.09) + \\ Contrast sensitivity (LogCS) & 1.82 (0.34) & 1.59 (0.80) & 1.96 (0.08) \\ TMT part A (s) & 55.3 (24.7) & 60.0 (38.5) & 27.4 (7.9) \\ TMT part B (s) & 138.2 (86.3) & 174.4 (102.4) & 89.8 (70.5) \\ Executive function (TMT B-TMT A) (s) & 82.9 (64.6) & 114.4 (71.3) & 62.4 (64.5) \\ Foot length (cm) & 22.4 (2.5) & 21.4 (1.7) & 21.6 (2.6) \\ Foot width (cm) & 8.5 (1.1) & 8.0 (0.6) & 8.2 (1.1) \\ \hline \hline \end{tabular}  
* One patient had no formal documentation confirming GMFCS level. + There was a significant main effect of group on visual acuity (TD v CP DI; \(p\) = 0.01). There were no significant main effects of group on age (_p_ = 0.87), height (_p_ = 0.62), mass (_p_ = 0.81), contrast sensitivity (_p_ = 0.36), TMT part A (_p_ = 0.052), TMT part B (_p_ = 0.17), executive function (_p_ = 0.30), foot length (_p_ = 0.52), or foot width (_p_ = 0.68), as determined via a one-way between group ANOVA.  
\end{table}
Table 1: Participant characteristics (mean (ISD)).