Mrs. Thompson, an 82-year-old woman, resides in a long-term care facility due to advanced dementia. She has a history of osteoarthritis and frequently experiences pain in her joints. Mrs. Thompson has limited verbal communication abilities and often relies on non-verbal cues to express discomfort. When using the PAINAID scale to assess Mrs. Thompson's pain level, which of the following non-verbal cues should the nurse primarily focus on?