3.2. Eye Tracking Analysis of AOIs
Eye-tracking data were processed and statistically analyzed using a VR plug-in and MATLAB. As described in
Section 2.5.2, a separate linear mixed-effects model was fitted for each eye-tracking outcome. Fixed effects included Group (children vs. adults), Scenario (SC0–SCX), and their Group × Scenario interaction. Subject_ID was specified as a random intercept.
In the following, we focus on the main fixed effects related to Group and Scenario. The main and interaction effects of Order were small and non-significant (see
Appendix A Table A1 and
Table A2) and are therefore not discussed further in the main text. This section concentrates on the proportion of fixation duration within the Zebra crossings AOI and the Left/right zebra crossings AOI.
(1) Gaze proportion on Zebra crossings AOI
As shown in
Figure 10 and
Appendix A Table A1, under the baseline condition (child group, SC0), the mean proportion of fixation time within the Zebra crossings AOI was about 0.49 (Estimate = 0.490, 95% CI [0.428, 0.553]). In the same baseline scenario, adults showed a significantly lower fixation proportion on this AOI than children (Group--Adult: Estimate = −0.171, 95% CI [−0.274, −0.068],
p = 0.0012), but the standardized effect size was very small (|effect size| ≈ 0.015), indicating that although the between-group difference in attention to the zebra crossing itself was statistically significant, its practical magnitude was limited.
Using the child group as the reference, most intervention scenarios increased the fixation proportion on the Zebra crossings AOI relative to SC0. The scenario main effects were most pronounced in SC3 (Color-Coded Arrows), SC4 (Tactile Paving Patterns), and SCX (combined scheme) (SC3: Estimate = 0.119, 95% CI [0.059, 0.179], p ≈ 1.1 × 10−4; SC4: Estimate = 0.145, 95% CI [0.086, 0.205], p ≈ 2.5 × 10−6; SCX: Estimate = 0.128, 95% CI [0.069, 0.188], p ≈ 3.0 × 10−5). The corresponding standardized effect sizes were in the small range (effect size ≈ 0.010–0.013), consistently indicating that Color-Coded Arrows and Tactile Paving Patterns further enhanced children’s visual focus on the zebra crossing itself. SC1 and SC2 showed only trend-level or non-significant increases (e.g., SC1: p = 0.056), and the main effect of SC5 (Stop line) was not significant (Estimate = −0.025, 95% CI [−0.085, 0.034], p = 0.40).
The Group × Scenario interaction terms for the Zebra crossings AOI were generally non-significant (all p > 0.12, effect sizes near 0), suggesting that the “pattern of increased fixation proportion relative to SC0” was broadly similar between children and adults, with no clear age-group–specific gains.
Because multiple Scenario-related tests were conducted for the same outcome, all scenario main effects and Group × Scenario interactions were treated as a single family of tests, and the Benjamini–Hochberg procedure was used to control the false discovery rate (FDR; q = 0.05). After correction, the scenario main effects for SC3, SC4, and SCX remained statistically significant, whereas SC1 shifted from marginally significant to non-significant, indicating that the facilitative effects of Color-Coded Arrows and Tactile Paving Patterns on zebra-crossing fixations were robust under multiple-comparison control. The marginal and conditional R2 of this mixed model were both very close to 1 (R2_marginal ≈ 0.9998, R2_conditional ≈ 0.9999), implying that the fixed effects together with between-subject random variation almost completely accounted for the variance in this outcome. The standard deviation of the Subject_ID random intercept was about 0.13 (95% CI [0.11, 0.17]), indicating some stable individual differences in overall fixation levels on the zebra crossing.
(2) Gaze proportion on left/right zebra crossings AOI
The Left/right zebra crossings AOI primarily reflects participants’ Left-Right Scanning behavior in the areas on both sides of the zebra crossing. As shown in
Figure 11 and
Appendix A Table A2, under the baseline scenario SC0, the mean fixation proportion on this AOI was close to zero in the child group (Estimate = 0.008, 95% CI [−0.009, 0.025],
p = 0.36), indicating that, in the absence of any visual guidance, children allocated relatively little attention to the left and right sides. In contrast, adults showed a significantly higher fixation proportion than children in the baseline scenario (Group-Adult: Estimate = 0.083, 95% CI [0.054, 0.111],
p ≈ 2.3 × 10
−8), although the standardized effect size was again small (effect size ≈ 0.007). This suggests that adults were generally more inclined to distribute part of their gaze to both sides, but the magnitude of this difference was modest on the present measurement scale.
Regarding scenario main effects, SC1–SCX did not significantly change the Left/right AOI fixation proportion in the child group (all 95% CIs crossed zero, p ≥ 0.64), and no stable scenario main effect comparable to that for the Zebra crossings AOI was observed. Among the Group × Scenario interactions, Group--Adult: Scenario_SC5 reached significance before correction (Estimate = 0.044, 95% CI [0.012, 0.076], p = 0.0073), suggesting an additional increase in adults’ fixation allocation to the two sides of the zebra crossing relative to children in the Stop line scenario (SC5). Group-Adult: Scenario_SC1 showed a slight negative interaction (Estimate = −0.033, 95% CI [−0.065, −0.001], p = 0.042), indicating a narrowed group difference in Left-Right Scanning under the Look left markings scenario. However, all of these interaction effects had extremely small standardized magnitudes (|effect size| ≤ 0.004).
When all scenario main effects and Group × Scenario interactions for this outcome were treated as a single family of tests and corrected using the Benjamini–Hochberg FDR procedure, none of the scenario-specific effects remained significant; only the main effect of Group stayed significant. This pattern supports a robust conclusion that, across scenarios, adults were generally more likely than children to allocate part of their visual attention to the areas on both sides of the zebra crossing, whereas the additional modulation of this Left-Right Scanning behavior by specific scenarios was relatively limited. The marginal and conditional R2 of the Left/right AOI model were also close to 1 (R2_marginal ≈ 0.99998, R2_conditional ≈ 0.99999), and the standard deviation of the Subject_ID random intercept was about 0.03 (95% CI [0.024, 0.038]), indicating only small stable individual differences on this outcome.
(3) Age subgroup differences among children
To account for potential cognitive differences associated with age, we further compared gaze allocation between the two child subgroups (6–8 years vs. 9–10 years) across Scenario × AOI conditions. For logit-transformed fixation proportions, Welch’s t tests were applied, and Holm adjustment was used to correct for multiple comparisons. As shown in
Table 4, all adjusted
p values (
p_adj) for Scenario × AOI comparisons exceeded 0.05 (minimum
p_adj ≈ 0.63), and no statistically significant age-group differences were detected. Most effect sizes fell within the small range (|d| ≈ 0.11–0.36), with a few comparisons showing medium-sized trends (e.g., SCX, AOI = Left/right zebra crossings: Diff = −1.07, d ≈ −0.64), which nevertheless did not reach significance after multiple-comparison correction. Overall, the presentation of key visual elements across scenarios appeared to have broadly similar “legibility” for children in both age ranges. However, “non-significant” does not imply “identical,” and these patterns should be further examined in larger samples.
3.3. Motion Capture Data Analysis
For the three behavioral outcome measures—Average walking speed, Gait variability, and Stopping duration—we applied the same linear mixed-effects modeling approach as in
Section 3.2. Fixed effects included Group, Scenario, and their Group × Scenario interaction, with Order entered as a covariate and Subject_ID specified as a random intercept. Below, we report the estimated fixed effects,
p values, 95% confidence intervals (95% CI), effect sizes, and the variance of the random intercept together with R
2 values; detailed numerical results are provided in
Appendix A Table A3,
Table A4 and
Table A5.
(1) Average walking speed
Under the baseline condition (child group, SC0), Average walking speed was approximately 2.88 m/s (Estimate = 2.88, 95% CI [2.55, 3.21]). In the same baseline scenario, adults walked slightly more slowly than children (Group_Adult: Estimate = −0.31, 95% CI [−0.85, 0.23], p = 0.25). The confidence interval crossed zero, and the standardized effect size was very small (effect size ≈ −0.027), indicating no clear systematic difference in baseline walking speed between children and adults.
Using the child group as the reference, the estimated effects of the intervention scenarios relative to SC0 were generally small. For SC1–SC5 and SCX, the absolute values of the coefficients were all below 0.21 m/s (e.g., SC3: Estimate = 0.21, 95% CI [−0.13, 0.55]), with corresponding standardized effect sizes |effect size| of about 0.01–0.02. All scenario main-effect 95% CIs crossed zero, and all p values were > 0.05. After treating these as a single family of tests and applying Benjamini–Hochberg FDR correction, none of the scenario main effects reached statistical significance.
For the Group × Scenario interactions, only the interaction in SC3 showed a marginal trend (Group_Adult:Scenario_SC3: Estimate = −0.53, 95% CI [−1.07, 0.02], p ≈ 0.059, effect size ≈ −0.046). All other interaction terms had effect sizes close to zero (|effect size| < 0.03) and p values far above 0.05. The marginal and conditional R2 of the Average walking speed model were 0.993 and 0.997, respectively. The standard deviation of the Subject_ID random intercept was about 0.67, comparable in magnitude to the residual standard deviation (≈0.69). This pattern suggests that there were some stable between-subject differences in overall “preferred walking speed,” but that walking speed remained relatively stable across scenarios and groups, with visual elements exerting only minimal influence on this outcome.
(2) Gait variability
For Gait variability, the baseline mean in the child group was about 0.147 (Estimate = 0.147, 95% CI [0.122, 0.172]). Adults showed a slightly lower value than children in SC0 (Group_Adult: Estimate = −0.021, 95% CI [−0.062, 0.019], p = 0.30), but this difference was not significant and the effect size was essentially zero (≈0.002).
Within the child group, all scenario main effects (Scenario_SC1–SCX) were extremely close to zero (|Estimate| < 0.012). All 95% CIs crossed zero, p values were far above 0.05, and the corresponding standardized effect sizes were very small (|effect size| < 0.002. A similar pattern emerged for the Group × Scenario interactions: all interaction estimates lay within a very narrow range (−0.014 to 0.014), with confidence intervals spanning zero, p values > 0.5, and absolute effect sizes generally < 0.002. In other words, for both children and adults, the impact of the intervention scenarios on gait rhythm was negligible, and multiple-comparison correction does not change this conclusion.
The marginal and conditional R2 for this model were approximately 0.99996 and 0.99998, respectively. The standard deviations of the random intercept and the residuals were both around 0.05, indicating that under the present task demands and spatial scale, Gait variability was extremely stable both within and between individuals. The model was almost entirely explained by “fixed between-subject differences plus small random fluctuations.”
(3) Stopping duration
In contrast to the other two indicators, Stopping duration was highly sensitive to scenario manipulations. Under the baseline condition (child group, SC0), mean stopping time was about 2.26 s (Estimate = 2.26, 95% CI [1.81, 2.71]). In the same baseline scenario, adults showed a slightly longer stopping time than children (Group_Adult: Estimate = 0.21, 95% CI [−0.52, 0.93], p = 0.58), but this difference was not significant, and the effect size was small (≈0.018). Thus, in the absence of visual interventions, children and adults exhibited broadly similar stopping behavior.
Using the child group as the baseline, most intervention scenarios significantly prolonged stopping time:
SC1 (Footprint (stop) markings + Traffic bollard): Estimate = 2.18 s, 95% CI [1.76, 2.60], p ≈ 1.4 × 10−21, effect size ≈ 0.19;
SC2 (Look left markings): Estimate = 1.55 s, 95% CI [1.13, 1.97], p ≈ 2.6 × 10−12, effect size ≈ 0.13;
SC4 (Tactile Paving Patterns): Estimate = 0.72 s, 95% CI [0.30, 1.14], p ≈ 8.7 × 10−4, effect size ≈ 0.06;
SC5 (Stop line): Estimate = 0.49 s, 95% CI [0.07, 0.91], p ≈ 0.021, effect size ≈ 0.04;
SCX (combined intervention): Estimate = 2.64 s, 95% CI [2.22, 3.06], p ≈ 2.3 × 10−29, effect size ≈ 0.23.
For SC1, SC2, SC4, SC5, and SCX, the scenario main effects remained significant after FDR correction across all Scenario-related coefficients, with effect sizes in the small-to-moderate range (≈0.04–0.23). These results indicate that these interventions substantially extend children’s stopping time and strengthen a safer “stop–scan–then cross” behavior pattern.
The Group × Scenario interactions capture group differences in “change relative to SC0.” In SC1, SC2, SC4, and SCX, the Group_Adult:Scenario coefficients were significantly negative. For example:
SC1: Estimate = −1.58 s, 95% CI [−2.25, −0.91], p ≈ 5.1 × 10−6, effect size ≈ −0.14;
SC2: Estimate = −1.26 s, p ≈ 2.6 × 10−4, effect size ≈ −0.11;
SCX: Estimate = −1.80 s, p ≈ 2.2 × 10−7, effect size ≈ −0.16.
These negative interactions indicate that, relative to SC0, the “stopping-time extension effect” of these scenarios was more pronounced in children. Adults also showed some increase in stopping time, but to a clearly smaller degree. In contrast, the interaction terms for SC3 and SC5 were not significant, suggesting that in these two scenarios the relative magnitude of stopping-time extension was more similar between children and adults.
For the Stopping duration model, the marginal and conditional R2 were approximately 0.988 and 0.995, respectively. The standard deviation of the Subject_ID random intercept was about 0.96 s, and the residual standard deviation was about 0.84 s, indicating substantial stable between-subject differences in overall “stopping preference,” while scenario manipulations still accounted for a considerable proportion of the remaining variance.
Taken together, the three behavioral indicators show that Average walking speed and Gait variability were only weakly sensitive to visual elements in the present experimental setting, with very small differences across scenarios. By contrast, Stopping duration was strongly responsive to visual interventions. In particular, scenarios incorporating Footprint (stop) markings, Traffic bollard, Look left markings, and multi-element combinations produced clear, statistically and behaviorally meaningful enhancements in children’s stopping behavior.