27 lines
1.7 KiB
Markdown
27 lines
1.7 KiB
Markdown
---
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id: pain-expressivity
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title: Pain Expressivity
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---
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Similar to emotion expressivity, pain expressivity is calculated using a combination of action units as defined in the Facial Action Coding System (FACS)[^1]. 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.[^2]
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[^1]: https://en.wikipedia.org/wiki/Facial_Action_Coding_System
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[^2]: Prkachin, Kenneth M. (1992). The consistency of facial expressions of pain: a comparison across modalities. Pain, 51(3), 297–306.
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## Raw Variables
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| Variable | Description |
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| ----------- | ----------- |
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| `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. |
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| `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. |
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## Derived Variables
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| Variable | Description |
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| ----------- | ----------- |
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| `fac_paiintsoft_pct` | Percentage of frames where at least one of the pain AUs were detected. |
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| `fac_paiintsoft_mean` | **Pain expressivity ‘soft’ mean,** equal to the average of all `fac_paiintsoft` values. |
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| `fac_paiintsoft_std` | **Pain expressivity ‘soft’ standard deviation.** |
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| `fac_paiinthard_mean` | **Pain expressivity ‘hard’ mean,** equal to the average of all fac_paiinthard values. |
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| `fac_paiinthard_std` | **Pain expressivity ‘hard’ standard deviation.** |
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