# Visual Demands of Walking Are Reflected in Eye-Blink-Evoked EEG-Activity
## 3 Results
### EEG Parameters
#### 3.2.2. ERPs  
**Theta:** The Theta base level (see Figure 5) decreased for standing compared to walking on the meadow (F(1,35) = 68.13, \(p\) < 0.001, \({}_{\text{adj}}\eta_{\text{p}}{}^{2}\)=.65). Furthermore, an interaction of walking condition by channel pool (topography) was observed (F(3,105) = 16.21, \(p\) < 0.001, \({}_{\text{adj}}\eta_{\text{p}}{}^{2}\) = 0.29). This was due to the effect of walking being most pronounced at occipital sites, both numerically and with respect to statistical power (frontal: F(1,35)=43.58, \(p\) < 0.001, \({}_{\text{adj}}\eta_{\text{p}}{}^{2}\) = 0.54; temporal: F(1,35) = 32.63, \(p\) < 0.001, \({}_{\text{adj}}\eta_{\text{p}}{}^{2}\) = 0.47, parietal: F(1,35)=27.51, \(p\) < 0.001, \({}_{\text{adj}}\eta_{\text{p}}{}^{2}\) = 0.42; occipital: F(1,35) = 132.97, \(p\) < 0.001, \({}_{\text{adj}}\eta_{\text{p}}{}^{2}\) = 0.79). The Theta base level additionally increased with block (F(1,35) = 10.20, \(p\) = 0.006, \({}_{\text{adj}}\eta_{\text{p}}{}^{2}\) = 0.20). This effect was strongest at occipital sites as well (frontal: F(1,35) = 2.18, \(p\)>.1; temporal: F(1,35) = 4.96, \(p\) = 0.064, \({}_{\text{adj}}\eta_{\text{p}}{}^{2}\) = 0.10; parietal: F(1,35)=4.39, \(p\) = 0.086, \({}_{\text{adj}}\eta_{\text{p}}{}^{2}\) = 0.09; occipital: F(1,35) =12.19, \(p\) = 0.002, \({}_{\text{adj}}\eta_{\text{p}}{}^{2}\) = 0.24). When the two walking conditions are compared, neither walking condition nor block modulated Theta base power. Theta perturbations were lower in power for walking on the meadow compared to standing (F(1,35) = 16.22, \(p\) < 0.001, \({}_{\text{adj}}\eta_{\text{p}}{}^{2}\) = 0.30), an effect which was modulated by topography (F(1,35) = 25.60, \(p\) < 0.001, \({}_{\text{adj}}\eta_{\text{p}}{}^{2}\) = 0.41), with the effect of walking being clearly visible only at temporal and occipital sites (temporal: F(1,35) = 13.41, \(p\) < 0.001, \({}_{\text{adj}}\eta_{\text{p}}{}^{2}\) = 0.26; occipital: F(1,35) = 36.54, \(p\) < 0.001, \({}_{\text{adj}}\eta_{\text{p}}{}^{2}\) = 0.50), but not at frontal or parietal sites (frontal: F(1,35) = 2.98, \(p\) > 0.1); parietal: F(1,35) = 0.50, \(p\) > 0.1). Though the main effect of factor experimental block did not reach significance (F(1,35) = 1.87, \(p\) > 0.1), a slight decrease in evoked Theta power was observed in the second block while standing (interaction of walking condition x block: F(1,35) = 7.52, \(p\) = 0.019, \({}_{\text{adj}}\eta_{\text{p}}{}^{2}\) = 0.15). Additionally, when the two walking conditions are compared, Theta perturbations decreased with walking complexity (F(1,35) = 31.28, \(p\) < 0.001, \({}_{\text{adj}}\eta_{\text{p}}{}^{2}\) = 0.46). This effect was most pronounced at the frontal and occipital leads (interaction of topography x walking condition: F(3,105) = 10.55, \(p\) < 0.001, \({}_{\text{adj}}\eta_{\text{p}}{}^{2}\) = 0.21; frontal: F(1,35) = 10.41, \(p\) = 0.005, \({}_{\text{adj}}\eta_{\text{p}}{}^{2}\) = 0.21; temporal: F(1,35) = 10.77, \(p\) = 0.021, \({}_{\text{adj}}\eta_{\text{p}}{}^{2}\) = 0.21; parietal: F(1,35) = 4.79, \(p\) = 0.071; occipital: F(1,35) = 33.37, \(p\) < 0.001, \({}_{\text{adj}}\eta_{\text{p}}{}^{2}\) = 0.47). **Alpha:** The Alpha base level (see Figure 6) did not differ for the comparison of standing vs. walking on the meadow (F(1,35) = 1.74, \(p\) > 0.1), but an interaction of walk  
Figure 5: Level of Theta power and task-related perturbations (means and standard error of means) for the three walking conditions and separated for the two blocks. Theta level was higher for standing compared to both walking conditions. Theta perturbations decreased in power with increasing complexity of the walking conditions. Significant effects of walking condition are depicted for all pairwise comparisons (***: \(p\) < 0.001; *: \(p\) < 0.05; +: \(p\) < 0.1).