TABLE 2.
Correlation matrix for self-reported outcomes and facial muscle activation for the Smile Stick manipulation.
| Comfort | Muscle fatigue | Difficulty | Positive affect | Negative affect | Aroused | Unaroused | ZMM activation change score | OOM activation change score | |
| Comfort | 1 | −0.124 | –0.389∗∗ | 0.305∗∗ | –0.038 | 0.236∗∗ | –0.137 | –0.055 | –0.062 |
| Muscle fatigue | – | 1 | 0.434∗∗ | −0.166∗ | 0.426∗∗ | –0.092 | 0.280∗∗ | 0.100 | –0.012 |
| Difficulty | – | – | 1 | –0.002 | 0.289∗∗ | 0.008 | 0.125 | 0.032 | –0.019 |
| Positive affect | – | – | – | 1 | –0.099 | 0.516∗∗ | −0.194∗ | 0.037 | 0.080 |
| Negative affect | – | – | – | – | 1 | 0.085 | 0.293∗∗ | 0.080 | 0.084 |
| Aroused | - | – | – | – | – | 1 | –0.392∗∗ | 0.130 | 0.074 |
| Unaroused | – | – | – | – | – – | − | 1 | –0.112 | –0.159 |
| ZMM activation change score | – | – | – | – | – | – | – | 1 | 0.661∗∗ |
| OOM activation change score | – | – | – | – | – | – | – | – | 1 |
ZMM, zygomaticus major muscle; OOM, orbicularis oculi muscle. ∗p < 0.05, ∗∗p < 0.01.