Table 3.
Parameter estimates from general linear mixed models (LMM) for percent change in oxytocin (OT) concentration and percent change in behavioral measures (proximity, contact, lip-smacking, back-arching/tail-lashing, restraining, movement, and breaking affiliation) from control to mirror condition predicted by males who display high levels of partner-directed aggression (High-aggressive; N = 10) relative to those who display low levels of partner-directed aggression (Low-aggressive). For all behaviors, models included male’s aggression score (High-aggressive; N = 10), percent change in OT concentration from the control condition to the mirror condition (OT), and an interaction between aggression and percent change in OT (High-aggressive*OT). The dependent variables percent change in proximity, contact, lip-smacking, arch/lash, and restrain were log transformed; therefore, estimates are interpreted percent change in the behavior increasing 100*Estimate percent for every one unit increase in the independent variable (High-aggressive, OT, and High-aggressive*OT). The dependent variables percent change in OT concentration, movement, and break affiliation were not transformed. Estimates for percent change in OT concentration relative to baseline is 12 ± 9% for Low-aggressive males and 12 ± 9% - 22 ± 10% for High-aggressive males. Estimates for percent change in movement from the control to mirror condition is equal to 178 ± 46% for Low-aggressive males and 178 ± 46% - 112 ± 65% for males in the High-aggressive category. Estimates for percent change in breaking affiliative contact is equal to 53 ± 35% for Low-aggressive males and 53 ± 35% + 8 ± 50% for High-aggressive males.
| β | SE | t | P | |
|---|---|---|---|---|
| 3A: Oxytocin | ||||
| Intercept | 0.12 | 0.09 | 1.35 | 0.32 |
| High-aggressive | −0.22 | 0.1 | −2.2 | 0.04 |
| 3B: Contact | ||||
| Intercept | 1 | 0.47 | 2.13 | 0.17 |
| High-aggressive | −1.35 | 0.6 | −2.26 | 0.04 |
| OT | −1.91 | 1.27 | −1.51 | 0.15 |
| 3C: Lip-smacking | ||||
| Intercept | 1.55 | 0.3 | 5.2 | < 0.01 |
| High-aggressive | −1.02 | 0.44 | −2.32 | 0.03 |
| OT | −1.31 | 0.93 | −1.4 | 0.18 |
| 3D: Proximity | ||||
| Intercept | 0.19 | 0.69 | 0.28 | 0.81 |
| High-aggressive | 1.03 | 0.75 | 1.38 | 0.19 |
| OT | −0.19 | 1.72 | −0.11 | 0.91 |
| High-aggressive*OT | 6.8 | 3.48 | 1.96 | 0.07 |
| 3E: Restrain | ||||
| Intercept | 0.582 | 0.26 | 2.237 | 0.038 |
| High-aggressive | −0.38 | 0.368 | −1.034 | 0.315 |
| 3F: Back-Arch/ Tail-Lash | ||||
| Intercept | 1.35 | 0.35 | 3.88 | < 0.01 |
| High-aggressive | −0.3 | 0.52 | −0.58 | 0.57 |
| OT | −1.42 | 1.23 | −1.16 | 0.26 |
| High-aggressive*OT | 4.53 | 2.5 | 1.82 | 0.09 |
| 3G: Movement | ||||
| Intercept | 1.78 | 0.46 | 3.88 | < 0.01 |
| High-aggressive | −1.12 | 0.65 | −1.72 | 0.1 |
| 3H: Break Affiliation | ||||
| Intercept | 0.53 | 0.35 | 1.51 | 0.15 |
| High-aggressive | 0.08 | 0.5 | 0.15 | 0.88 |