Similar to emotion expressivity, pain expressivity is calculated using a combination of action units as defined in the Facial Action Coding System (FACS). The following action units have been found to be associated with pain according to reports in the scientific literature: 4 + 6 + 7 + 9 + 10 + 12 + 20 + 26.
Raw Variables
| Variable | Description |
|---|
fac_paiintsoft | Pain intensity ‘soft’. Continuous vector indicating intensity of pain in each video frame regardless of whether all action units for that emotion are present. Range is between 0 and 1. |
fac_paiinthard | Pain intensity ‘hard’. Continuous vector indicating intensity of pain in each video frame, only providing non-zero value if all action units for that emotion are present. Range is between 0 and 1. |
Derived Variables
| Variable | Description |
|---|
fac_paiintsoft_pct | Percentage of frames where at least one of the pain AUs were detected. |
fac_paiintsoft_mean | Pain expressivity ‘soft’ mean, equal to the average of all fac_paiintsoft values. |
fac_paiintsoft_std | Pain expressivity ‘soft’ standard deviation. |
fac_paiinthard_mean | Pain expressivity ‘hard’ mean, equal to the average of all fac_paiinthard values. |
fac_paiinthard_std | Pain expressivity ‘hard’ standard deviation. |