Table 2 Descriptive statistics of the fixation-based measures for each scene condition split by zygosity. Statistics presented as Mean (SD)/min-max. MZ monozygotic, DZ dizygotic.
|  | n | Overall | Skew | MZ (n = 291) | DZ (n = 245) |
|---|---|---|---|---|---|
Naturalistic condition | |||||
 # Fixations | 521 | 43.64 (27.65) 5–125 | 0.52 | 45.82 (27.78) 5–115 | 41.07 (27.32) 5–125 |
 Proportion missing gaze | 521 | 0.10 (0.11) 0–0.46 | 1.25 | 0.10 (0.11) 0–0.46 | 0.10 (0.12) 0–0.45 |
 Mean RMS | 521 | 0.66 (0.25) 0.17–1.33 | 0.11 | 0.63 (0.26) 0.17–1.33 | 0.69 (0.24) 0.18–1.28 |
 Mean fixation duration | 521 | 552.53 (115.77) 168.06–964.12 | − 0.16 | 553.40 (112.35) 186.67–964.12 | 551.50 (119.90) 168.06–908.33 |
 Proportion on face | 497 | 0.60 (0.21) 0–0.99 | − 0.52 | 0.59 (0.22) 0–0.99 | 0.62 (0.20) 0.05–0.99 |
 Proportion on active | 503 | 0.71 (0.16) 0.08–0.99 | − 1.46 | 0.70 (0.16) 0.08–0.95 | 0.72 (0.16) 0.14–0.99 |
Abstract condition | |||||
 # Fixations | 520 | 30.58 (20.62) 3–100 | 0.8 | 31.98 (20.39) 3–94 | 28.91 (20.81) 3–100 |
 Proportion missing gaze | 520 | 0.11 (0.12) 0–0.47 | 1.13 | 0.11 (0.12) 0–0.47 | 0.12 (0.12) 0–0.47 |
 Mean RMS | 520 | 0.70 (0.26) 0.17–1.5 | − 0.03 | 0.67 (0.26) 0.17–1.5 | 0.72 (0.25) 0.19–1.39 |
 Mean fixation duration | 520 | 602.84 (149.87) 138.89–1388.89 | 0.3 | 605.84 (146.23) 138.89–1388.89 | 599.22 (154.37) 209.72–1161.67 |
