- Examine the relationship between romantic ties and the experience of pain or pleasure
Relationships and Health
One of the greatest medicines in the world doesn’t come in pill form and it can’t be injected with a syringe. No surgery is required. It is other people.
An impressive amount of research from psychology and medicine supports the claim that having a strong social support network— supportive friends and family—is associated with maintaining both physical and psychological health and recovering quickly and effectively from physical and psychological problems. Loneliness and isolation are risk-factors to leading a healthy, happy life.
The goal of scientific psychology is to understand the deep underlying causes of psychological and behavioral factors. Evidence that there is an association between health and social support is the beginning—not the end—of scientific investigation. We want to know why such a relationship exists. This curiosity is not simply an academic exercise. Treatments can only be improved and targeted to specific needs if we understand how they work.
Correlations can identify interesting relationships (e.g., there is a positive correlation between a person’s amount of social support and success in recovering from physical and psychological problems), but they usually cannot provide strong evidence for why that relationship exists. That is the job of experiments.
When you design an experiment, you must often create a very specific situation to test and explore your ideas. We have been talking in grand terms about “social support networks” and “mental and physical health,” but individual experiments typically cannot work on such a broad scale. Instead, the experimenter tries to find a single simple type of social support that can be manipulated in the laboratory and a single simple element of health that can be measured and studied in the laboratory. One disadvantage of this sharp focus on a specific situation in experiments is that a single experiment—even a single set of related experiments—is unlikely to fully identify the causes we are looking for. Experimental evidence typically accumulates slowly, over long periods of time, filled with apparent contradictions that can take time and effort to sort out.
We are going to look at two experiments from different research teams that take a similar approach to trying to understand if social contact influences a health-related experience—in this case, pain—and how such an influence might work (i.e., what might be the causal mechanisms?).
Experiment 1: Love and Pain
Sarah L. Master and her colleagues conducted a simple experiment that they published in 2009. Their subjects were healthy college students who volunteered to participate in an experiment that tested the idea that contact with a romantic partner can reduce our experience of pain.
Master and her colleagues recruited heterosexual couples to participate in their study. The women were the actual subjects in the study. Their male partners participated as part of the experimental manipulation. The participants were in stable, long-term (defined here as longer than 6 months) relationships.
Before the experiment began, each woman was tested to find her personal pain experiences for thermal stimulation (i.e., heat), which was produced by a medical device called a thermode. Different people experience and report pain very differently, so calibration of the thermal stimulation to the individual’s pain experience was essential. The thermal stimulation during the experiment was adjusted to the point at which the subject reported a “moderate” level of discomfort (10 on a 20-point discomfort scale) when the heat was applied. This means that different people experienced different objective amounts of heat, while the subjective “discomfort” should have been approximately the same. The heat stimulus was delivered to the soft inside of the right forearm, and each one lasted for 6 seconds.
There were seven conditions in the experiment.
In three of the conditions, the woman held something in her hand as she experienced the painful thermal stimulation. She held either:
- The hand of her partner (who sat behind a curtain, and—except for his hand—was not visible).
- The hand of a male stranger (who was also behind a curtain).
- An object: a squeeze ball.
In three other conditions, the woman looked at a picture on a computer screen in front of her. She saw either:
- A picture of her partner taken while the woman was being prepared for the experiment.
- A picture of a male stranger (similar age and matched for ethnicity with the woman’s partner).
- An object: a picture of a chair.
One control (or baseline) condition:
- The woman looked at a fixation cross on the computer screen.
The figure below shows summarizes the organization (technically, the “design”) of the experiment.
The woman received twelve thermal stimulations in each condition. The order of presentation of conditions was randomized for each woman. There was a 20-second break between stimulations. After each stimulation, the subject rated how “uncomfortable” the stimulus was on a 21-point scale.
A “condition” or “level” is a variation on something manipulated by the experimenter. An independent variable is made up of variations. For some procedure to be an independent variable, it must have at least two conditions (otherwise it is a constant and not a variable).
The results in this study are not shown on the original 21-point scale. To take account of individual differences, the control condition (i.e., looking at a fixation cross on a computer screen) the experimenters found the difference between each person’s average control condition unpleasantness rating and her rating for each condition. For example, imagine that one participant has the following average “unpleasantness” ratings (on the 21-point scale):
The control rating (10) is then subtracted from each of the treatment ratings. This becomes the score that is analyzed (called a “difference score”). This method allows each woman to have a different general pain level (in the example, it is “10” but another person might have “6” or “12” as her average). The difference score looks at each person’s change from her personal baseline under the various conditions. Here are the difference scores for the example above:
For the difference scores, a positive number means that the experience in that condition was more painful than it was in the control condition. A negative number means that the experience in that condition was less painful than it was in the control condition. The exact number used indicates how much more or less painful the experience was.
Before we show you the actual results of the experiment, we’d like you to predict what you think happened in this experiment. Use the figure below. The zero baseline is the control condition. Your predictions are about the six treatment conditions. You can click and drag on a bar to move the bar up, if you think that condition was more painful for the subject than the baseline control. And you can move a bar down if you think that condition was less painful than the baseline control condition.
The initial screen below shows all six of the treatment conditions as a tiny bit more painful than the baseline control. Make your predictions based on your own theory about the possible positive or negative effects of holding the hands of a person you love or of a stranger, or looking at a picture of a person you love or a stranger while you are in pain. Remember that zero baseline control is still very painful, so zero does not mean that there is no pain.
Let’s use these results to rank the order of the conditions in terms of their effect on pain. Drag the condition name on the right into the appropriate box next to the rank order number on the left.
These results suggest that there is something special about a person we love—or at least someone we like. Dr. Master noted that looking at a picture of a loved one may be slightly more beneficial than holding his hand, though this difference did not quite reach statistical significance. Holding a stranger’s hand exaggerated the pain experience by a considerable amount, so it is clear that (in the context of this experiment) human contact alone is not enough to relieve pain.
Dr. Master make a practical suggestion: If you are going to have a painful medical procedure, bringing a picture of someone you love may be helpful in reducing the pain. In fact, based on comparison of the hand holding and picture viewing conditions, you may actually be better off bringing a picture than bringing the actual person to the painful procedure.
Here is her final conclusion: “In sum, these findings challenge the notion that the beneficial effects of social support come solely from supportive social interactions and suggest that simple reminders of loved ones may be sufficient to engender feelings of support.” If you think back to the introduction to this activity, we said that our goal was to find out how and why social support leads to better health outcomes. As we cautioned you, this experiment doesn’t even come close to answering that question. However, it does take us one little step in the right direction, suggesting that “social support” may be more complicated than just having people near us or even a group of friends. “Social support” may involve triggering certain cognitive (mental) processes, such as memories and emotions, that are associated with strong positive relationships. That is for future research to clarify.
Experiment 2: Reducing Pain in the Brain
A completely different group of researchers, led by Jarred Younger at the Stanford University School of Medicine used fMRI (functional magnetic resonance imaging) to view the brains of people in an experiment very similar to the one you just studied. Just as in the previous study, they used heat to produce pain, though the location was at the base of the thumb on the palm of the left hand. They used two levels of heat, which they labeled as “moderate” and “high”. They only tested picture-viewing; there was no hand holding in this study.
Details of the Experiment
Younger and his colleagues tested both females and males by scanning their brains as they looked at pictures of romantic partners or mere friends. There was also a control condition explained below.
Each person brought to the experiment several pictures of his or her romantic partner. Only participants who reported being “intensely in love” and who scored at a very high level on the Passionate Love Scale (a standardized measure of passionate love) were included in the study. The participants also brought some pictures of a friend or acquaintance of the same gender and attractiveness as the romantic partner. In the experiment, the participants used the same procedures that were used in the other study you read. When looking at the picture, they were asked to focus on the picture and think about the person in the picture (romantic partner or friend).
For a third control or baseline condition, the experimenters wanted to see if looking at the picture was merely a distraction from the pain. In this distraction control condition, the participant was given a category name (e.g., animals, fruits, actors, politicians) and was asked to say aloud as many examples of that category as possible (ANIMALS: dog, bear, salmon, eagle, etc.).
Goal of the Experiment
The experimenters were interested in a very specific hypothesis. They wondered if thinking about someone we love intensely activates our brain’s reward system. This is a group of structures deep in the center of the brain surrounding some neural structures called the basal ganglia (see figure below). Among their reward-related activities is their production of the neurotransmitter dopamine, which they transport to regions throughout the brain. Dopamine is an important part of the pleasure and learning experiences associated with rewarding activities.
Because they were interested in testing the idea that the reward system might be activated by viewing someone we passionately love, the experimenters focused their brain scanning on the reward system areas shown above. However, they also looked at other brain areas, so they could determine if the reward system was more strongly associated with pain reduction than other areas.
Results of the Reward System Experiment
By now, you should have the idea that things are seldom simple in the world of science. First, the basic results from the first study you read about were found here as well. Participants reported significantly less pain when they looked at a picture of their romantic partner than when they looked at a stranger. Unfortunately (if you wanted simple results), almost exactly the same reduction in pain was found in the distraction control condition.
The figure below shows the results. These researchers used an 11-point pain scale (0=no pain, 10=worst pain imaginable), so the numbers cannot be directly compared to those in the first study. However, higher numbers mean more pain, so the results can be understood easily.
These results alone suggest that looking at pictures of someone we love may be nothing more than a distraction from the pain. However, this experiment was different than the first one because it had another dimension: the brain scans. What did they indicate?
Brain Imaging Results
The brain images add an interesting dimension to our understanding of pain and pain relief. When participants were looking at pictures of their romantic partner, the reward regions of the brain were very active. In fact, there was a strong correlation between the amount of activity in this region and the level of pain the person reported: more activity was associated with less pain.
If the reward systems (in the figure above, the red circle in the brain on the left) were also activated by the distraction task, then we are back to the idea that looking at our romantic partner is just a way of distracting ourselves. But that is NOT what they found. Activity in the reward regions of the brain were not strongly correlated with pain relief during the distraction task. However, other regions of the brain did have a strong relationship to pain relief in the distraction condition (see the blue circles on the brain to the right in the figure above). These are brain areas involved in memory, language, and making choices—exactly the systems that are active when we think about words that fit a particular category.
This study by Jarred Younger and his colleagues suggests that there may be multiple ways to reduce our experience of pain. The two approaches studied here (touching someone we love and generating words) may produce the similar analgesic effects: both result in less pain. But in terms of underlying causal mechanisms, such as the brain systems involved in reducing pain, very different things may be taking place.
This is not the end of the story. Finding a brain region associated with some experience is not an explanation; it is simply a first step in finding how a brain system works. Finding two sets of brain regions which both produce the same effect suggests that our explanation of how pain reduction is accomplished by the brain is not going to be simple.
Finally, if you were hoping to find out if there were sex differences in the effects we discussed, unfortunately the experimenters felt they did not have enough subjects to reliably test to see if men and women differ in their response to pain or in the regions of the brain associated with pain reduction. Perhaps one of you will conduct the experiment that answers those questions!
We started this exercise with a discussion of social support and health. People with stronger social support networks tend to have better health outcomes. When we asked how this works, we zoomed in on a very specific type of social support: a romantic relationship, which involve deep and complex connections between two people. It would be reasonable to suggest that this type of relationship might have the potential to produce the strongest possible form of social support.
Both experiments showed that social support in the form of touching someone we love (or seeing a picture of that person in the first experiment) can reduce pain, when compared to control conditions. The second experiment points to the brain’s reward system as a possible source of pain relief. We still don’t know the brain mechanism that produces the pain experience; it is possible that we fully feel the pain, but the positive feelings associated with the person we love balance out the negative experience of pain. Or perhaps the reward system can actually turn down the intensity of the pain experience, so we really feel less pain when we are with those we love. The scientists of your generation will have the opportunity to explore these mysteries.
- Sarah Master was then a graduate student at UCLA and is now a research associate with a Ph.D. at UCLA. Several of her co-authors are major figures in the field of health psychology. For example, co-author Shelly Taylor is one of the founders of the field of health psychology. ↵
- Researchers must often decide between restricting characteristics of their subjects to simplify factors influencing the results versus opening the experiment to a broader range of subjects to improve generalizability and representativeness. Restriction of the participants in this study to heterosexual couples does not imply that couples with other gender identities or sexual orientations are either unimportant or uninteresting. ↵
- Alternating among three different locations on different trials. ↵
- The randomization procedure was a bit more complicated than this explanation suggests. See the original paper if you want to know exactly what they did. ↵
- As any doctor will tell you, getting a valid and reliable rating of pain is notoriously difficult. Master and her colleagues used a scale (the Gracely Box Scale) that is widely used in research and has been extensively validated. ↵
- Jarred Younger, Arthur Aron, Sara Parke, Neil Chatterjee, and Sean Mackey. (2010). Viewing pictures of a romantic partner reduces experimental pain: Involvement of neural reward systems. PLoS one, 5 (10), e13309. ↵