More than meets the eye -- research tracks eye movements of those in chronic pain

People suffering with chronic pain pay more frequent and longer attention to pain-related words than individuals who are pain free, a York University study using eye-tracking technology has found.

Chronic pain currently affects about 20 per cent of the population in Canada. Knowing how and what people attend to may be important in determining who develops chronic pain and finding ways to prevent it, says Sam Fashler, a PhD student at York and lead author on the paper with York Professor Joel Katz published in the Journal of Pain Research.

Sam Fashler

Sam Fashler

Previous research used a dot-probe task to test reaction time when looking at pain-related and neutral words, but this study incorporated a more sophisticated measuring tool – an eye-tracker. “The use of an eye-tracker opens up a number of previously unavailable avenues for research to more directly tap what people with chronic pain attend to and how this attention may influence the presence of pain,” says Katz, Canada Research Chair in Health Psychology at York.

As Fashler says, “Our eye movements – the things we look at – generally reflect what we attend to.”

The researchers recorded both reaction time and eye movements of chronic pain and pain-free participants. Both groups viewed neutral and sensory pain-related words on a dot-probe task. They found reaction time did not indicate attention, but “the eye-tracking technology captured eye gaze patterns with millimetre precision,” says Fashler, which allowed them to determine how frequently and how long individuals looked at sensory pain words.

Joel Katz

Joel Katz

“We now know that people with and without chronic pain differ in terms of how, where and when they attend to pain-related words. This is a first step in identifying whether the attentional bias is involved in making pain more intense or more salient to the person in pain,” says Katz.

As the study did not look at whether this contributed to the development or maintenance of pain, Fashler will take the research a step further. She’ll examine what individuals attend to before and after surgery to determine if attentional biases predict the transition from acute to chronic pain. According to the Canadian Pain Society, 50 per cent of surgery patients have moderate to severe post-operative pain, while 10 to 50 per cent go on to have persistent post-operative pain.

“If we find that particular attentional tendencies are linked to the progression of pain, then we can develop interventions that modify visual attention biases,” she says. “This may benefit individuals by reducing the risk of developing chronic post-surgical pain or reducing pain severity in individuals already experiencing chronic pain.”

The article, “More than meets the eye: visual attention biases in individuals reporting chronic pain,” was published in the Journal of Pain Research.