Table 1.
(a) Estimated parameters (Estimate), Standard Error (SE), and results of the likelihood ratio tests (χ2) of the LMM (gaussian distribution) with Frontal Looking as response variable (Model1a). (b) Estimated parameters (Estimate), Standard Error (SE), and results of the likelihood ratio tests (χ2) of the GLMM (binomial error distribution) with Yawn Response as response variable (Model1c). For both the models the sessions were 102. Significant values are in bold.
| Fixed factors | Estimate | SE | df | X2 | p value |
|---|---|---|---|---|---|
| (a) Frontal looking. Variance for the random factor (tested individual) = 0.010, SD = 0.102 | |||||
| Intercept | 0.609 | 0.058 | – | – | – |
| Species | 2 | 8.825 | 0.012 | ||
| Species (human)a,b | − 0.017 | 0.035 | |||
| Species (mangabey)a,b | 0.079 | 0.034 | |||
| Condition (yawn)a,b | 0.049 | 0.028 | 1 | 3.086 | 0.079 |
| Sex (female)a,b | − 0.198 | 0.075 | 1 | 5.692 | 0.017 |
| Time (afternoon)a,b | − 0.030 | 0.029 | 1 | 1.056 | 0.304 |
| Order of the session | − 0.005 | 0.008 | 1 | 0.330 | 0.566 |
| (b) Yawn response. Variance for the random factor (tested individual) = 0.518, SD = 0.720 | |||||
| Intercept | − 0.040 | 1.074 | – | – | – |
| Species | 2 | 0.780 | 0.677 | ||
| Species (human)a,b | − 0.379 | 0.593 | |||
| Species (mangabey)a,b | 0.123 | 0.593 | |||
| Condition (yawn)a,b | 1.287 | 0.507 | 1 | 7.182 | 0.007 |
| Sex (female)a,b | − 1.683 | 0.700 | 1 | 6.527 | 0.011 |
| Time (afternoon)a,b | − 0.857 | 0.518 | 1 | 2.951 | 0.086 |
| Order of the session | 0.207 | 0.142 | 1 | 2.199 | 0.138 |
| Frontal looking | 0.177 | 1.364 | 1 | 0.017 | 0.897 |
| Number of outside yawns | − 0.056 | 0.164 | 1 | 0.117 | 0.733 |
aEstimate ± SE refers to the difference of the response between the reported level of this categorical predictor and the reference category of the same predictor.
bThese predictors were dummy coded, with the “Species (Hamadryas)”, “Condition (Control)”, “Sex (Male)”, “Time (Morning)” being the reference categories.