Study 3:
Mikkelsen, Mai Bjørnskova,*; Neumann, Henrikea; Buskbjerg, Cecilie Raska; Johannsen, Majaa; O'Toole, Mia Skyttea; Arendt-Nielsen, Larsb,c; Zachariae, Roberta,d. The effect of experimental emotion induction on experimental pain: a systematic review and meta-analysis. PAIN 165(4):p e17-e38, April 2024.
The main goal in this review and meta-analysis was to (1) carefully look at all the available evidence on how purposely inducing emotions affects self-reported pain in experiments, and (2) figure out the average effect sizes for these emotional inductions on self-reported pain.
Findings suggest that inducing positive emotions seems to help reduce pain, but when it comes to inducing negative emotions, the picture isn't as clear.
The way we understand pain nowadays suggests that it's not just a one-way street—it can both influence and be influenced by our emotions. And there's a ton of research backing this up. (See my Pain! The other 4 letter word! for more on this.) We've seen that our emotions, whether they're positive or negative, can either make pain worse or help ease it. It has also been found that people dealing with mental health issues that involve emotional ups and downs often report more pain.
For years, researchers have been going back and forth on how intentionally stirring up emotions might change how we experience pain. Two main ideas have emerged: one says that the type of emotion—whether it's good or bad—makes a difference (valence hypothesis), while the other suggests that simply distracting ourselves from the pain could help lessen it (distraction hypothesis).
Valence Hypothesis
According to the valence hypothesis: when we're purposely made to feel negative emotions, it tends to make us more sensitive to pain. Conversely, if we are induced to feel positive emotions, it often helps dial down our sensitivity to pain. This idea lines up with what's called the motivational priming theory (MPT).
The MPT suggests we have two main systems at play: one that kicks in when we sense danger or potential harm, leading to ‘negative’ emotions and an increase in cortisol. (From an evolutionary point we would seek to avoid replicating this experience.) Another system that gears us towards things that help us survive and thrive, leading to ‘positive’ emotions and an increase in endorphins. (From an evolutionary point we would seek to replicate this experience.) This is the manifestation of how our brains are wired to react differently depending on whether we perceive situations as threatening or rewarding. If one of these systems is activated, it "primes" us to respond in certain ways to new stuff we encounter. If what we encounter matches up with the activated system, our reactions get amped up. But if it doesn't match, our reactions might not be as intense. (Think vigilance in the face of something new and unexpected vs familiarity with something predictable.)
Distraction Hypothesis
According to the distraction hypothesis: when we shift our attention away from pain, it can actually help lessen it. The idea is that when we focus on something other than the pain, our brains get better at processing non-painful stimuli and turn down the volume on the painful sensations (down regulation).
In simple terms, any kind of distraction that takes our mind off the pain could potentially make it hurt less. (This may indeed be one of the primary reasons that touch therapy has an effect!)
Demographic and psychological characteristics in this study:
Research shows that pain sensitivity can vary based on several factors. For instance, younger adults might feel pain more intensely compared to older adults, and women might experience more sensitivity to pain compared to men. Even the region someone is from could play a role—there seem to be differences in pain sensitivity between Eastern and Western cultures.
Beyond demographics, other things like personality traits and psychological factors can also influence how we perceive pain. For example, being high in neuroticism or tending to catastrophize about pain can make it feel worse, while having a strong internal locus of control—believing we have control over our own lives—might make pain feel less intense. And interestingly, people who are more susceptible to hypnosis tend to experience bigger reductions in pain sensitivity when they undergo hypnotic treatments aimed at easing pain.
An interesting tidbit: it turns out that visual stimuli can stir up our emotions more than sounds can. And when something stimulates us with both sights and sounds, like a movie clip, it tends to pack an even bigger emotional punch than something that only targets one sense, like just listening to music.
Limitations and draw backs in the study:
This meta-analysis specifically looked for articles published in English only, which can be limiting to the findings. Only studies that included subjects greater than 18 were included, limiting our ability to understand if these findings are reflected amongst pediatric populations. The most glaring concern with this review however is that it ONLY includes studies on nonclinical adults, with no signs of previous symptoms.
Though this is not un-common in studies it limits our understanding significantly as those already experiencing acute or chronic pain might may have been better able to predict discomfort, may have had more difficulty tapping into their ‘positive’ emotions or even tolerating the pain stimulis. This is a major draw back from a clinical standpoint but not significant in regards to the research itself.
The review specifically looked for studies that examined how deliberately inducing emotions affected self-reported pain. These studies had to measure pain either during or after the experiment where the emotions were induced. These methods allowed for the researchers to see how people's feelings impacted their experience of pain in controlled settings.
Studies were excluded if they spanned several days, were case studies, qualitative studies, or, any literature published outside traditional academic publishing channels, often referred to as grey literature.
Conclusion:
In conclusion, the research findings suggest that feeling ‘positive’ emotions can help ease pain, more so than feeling ‘neutral’ or ‘negative’. When it comes to ‘negative’ emotions, though, the results aren't as straightforward. Some studies show it might help with pain, while others aren't so sure.
Additionally, when looked at things from a Bayesian perspective, it seemed pretty certain that ‘positive’ emotions do make a difference in managing pain. But when it came to ‘negative’ emotions, the evidence wasn't as strong.
So, overall, it looks like feeling good can definitely help with pain relief. But we still need more research to fully understand how feeling bad might affect it. The studies that were looked at seemed to be moderately done, which adds to the confidence in these findings!
Clinical Applications:
The findings here could have some significant positive implications for everyday life and clinical settings. Right now, a lot of treatments focus mainly on easing ‘negative’ emotions and distress when it comes to pain management. Most touch therapies as well as clinical interventions focus on reducing symptoms, decreasing stressors and avoidance models around pain stimuli. There is little evidence to suggest that when a reduction of pain, stressors or ‘negative’ emotions occur that these experiences are replaced with ‘positive’ stress free expereinces.
It seems like boosting ‘positive’ emotions could be more clinically relevant than reducing ‘negative’ or ‘neutral’ emotions.
It is not simply about reducing the bad feelings; it's about actively increasing the good ones too. Interventions aimed at easing pain might benefit more from a shift towards promoting ‘positive’ emotions. That could mean things like encouraging patients to do things they enjoy, finding the bright side of situations, and really savoring those happy moments. (Or as I have taught in many of my classes, integrating laughter into our treatment modules.)
It could be really enlightening to see if changes in ‘positive’ emotions actually play a role in how well these treatments work. Understanding that link better could give us even more tools to help people manage pain and improve their overall well-being.
As always, more research needs to be done to better understand the possible effects of ‘positive’ emotions of pain.