Can your doctor’s beliefs about the efficacy of a treatment affect how you experience pain? In episode 65, we’re joined by Luke Chang from the Department of Psychological & Brain Sciences at Dartmouth College. He talks with us about his research into socially transmitted placebo effects, through which patients can pick up on subtle facial cues that reveal their doctor’s beliefs about how effective a treatment will be. His article “Socially transmitted placebo effects” was published with Pin-Hao Chen, Jin Hyun Cheong, Eshin Jolly, Hirsh Elhence, and Tor Wager on October 21st, 2019 in Nature Human Behaviour.

Transmitting Placebo Effects - Luke Chang
Transmitting Placebo Effects - Luke Chang
Transmitting Placebo Effects - Luke Chang Transmitting Placebo Effects - Luke Chang
@rwatkins says:
Next time, in episode 66 of Parsing Science, we’ll be joined by Katherine Wood from the University of Illinois’ Department of Psychology. She’ll talk with us about her research with Daniel Simons - the scientist behind the famous “Invisible Gorilla” experiment - into if and when people notice unexpected objects in inattentional blindness tasks.
@rwatkins says:
We wrapped up our conversation by asking Luke if he's planning on extending this line of research into what might make otherwise effective treatments become ineffective ... or placebos become effective.
@rwatkins says:
The team's third study also replicated their previous findings, suggesting that doctors' subtle facial cues do indeed transmit placebo effects. But since quantitative studies are better at identifying what's going on than they are at explaining why, we asked Luke what some alternative explanations of their findings might be.
@rwatkins says:
As solid and Luke and his team's findings were, peer reviewers of their paper made several critiques that required that they return to the lab to carry out a final study, as Luke describes next.
@rwatkins says:
Luke and his colleague's first study examined if the transmission of beliefs between doctor and patient was mediated by the doctor’s facial expressions. And their second study sought to replicate this with a new sample of participants and several tweaks to the experimental set-up. We'll hear what they found after this short break.
@rwatkins says:
We followed up by asking Luke for more details on how these video recordings of people experiencing pain were analyzed to train this model.
@rwatkins says:
Luke and his team's study involved three related experiments. The first involved both patients’ and doctors’ facial expressions being recorded using custom head-mounted video cameras. Combined with self-assessments completed by patients, as well as measures of their sweat gland activity, these data were later used to train a computational algorithm which predicts the pain through facial expressions alone, as Luke explains next.
@rwatkins says:
The placebo effect is the reason that all FDA approved drugs have to go through a double-blind placebo-controlled clinical trial before being approved for use. But this gold standard of evidence only works if participants remain blinded to whether they're on the real treatment or the placebo. However, doing so can be challenging, particularly when a course of treatment is well-known for its side-effects, such as hair loss during chemotherapy. Luke talked with us about how researchers sometimes create placebos which - for this very reason - aren't inert "sugar pills" but rather actively induce side-effects.
@rwatkins says:
In 1803, the New Medical Dictionary defined placebos as "any medicine adapted more to please than to benefit the patient" and although this definition may have been an unflattering one, it also didn't necessarily imply that they have no effect. Given the long history of such remedies, Doug and I were curious what prior research has found with regard to their efficacy.
@rwatkins says:
Luke and his colleagues were interested in learning whether people playing the role of doctors might transmit their expectations about the effectiveness of medications to patients when the doctors' were falsely led to believe an that analgesic was either a real treatment ... or a placebo. Ryan and I asked Luke to describe the clever deceptions required for this study.
@rwatkins says:
Researchers' desire to minimize the effects of patients’ and clinicians’ expectations has led to the adoption of the double-blind randomized clinical trial as the gold standard for testing new medical treatments. In theory, both the physician and patient are unaware of whether the patients are being administered a new treatment or a placebo in such experiments. But - as we'll more about hear in a moment - Luke and his team's study employed a mock single-blind design in which "doctors" believed that they were administering a real analgesic cream or sham one, though in reality both creams were inert. Next, Luke explains what led him to explore interactions within two-person dyads such as he did in this study.
@rwatkins says:
Coined by the Austrian psychoanalyst Wilhelm Stekel in 1924, somatization is the process by which psychological distress may be expressed through physical symptoms, such as head and stomach aches. As it’s an area of Luke’s expertise, we began our conversation by asking him how he got interested in the topic.
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Hosts / Producers

Ryan Watkins & Doug Leigh

How to Cite

Watkins, R., Leigh, D., & Chang, L.. (2020, January 7). Parsing Science – Transmitting Placebo Effects. figshare.


What’s The Angle? by Shane Ivers


Luke Chang: I’m more shocked when something works than when it doesn’t. And so, at first I was like – I just didn’t believe that it actually worked.

Ryan Watkins: This is Parsing Science: the unpublished stories behind the world’s most compelling science, as told by the researcher themselves. I’m Ryan Watkins.

Doug Leigh: And I’m Doug Leigh. Today, in episode 65 of Parsing Science, we’re joined by Luke Chang from Dartmouth College’s Department of Psychological & Brain Sciences. He’ll talk with us about his research into how our beliefs in doctors’ expectations of how effective a treatment will be can influence our body’s experience of – and responses to – pain. Here’s Luke Chang.

Chang: I’m Luke Chang. I was born in St. Louis, Missouri and grew up in Denver, Colorado. I attended college at Reed College in Portland Oregon, and then I did a master’s in psychology at the New School for Social Research in New York. And then I transferred to start my PhD in clinical psychology at the University of Arizona in Tucson, Arizona, and then completed a clinical internship in behavioral medicine at the University of California at Los Angeles. And then a postdoc fellowship in neuroimaging methods and placebos and pain research with Tor Wager at the University of Colorado in Boulder. And I started as an assistant professor at Dartmouth College in 2015. So I’ve been here about four years.

You know, being trained as a clinician I was always really interested in how, like, psychotherapy worked. And in the beginning I was, like, really skeptical about it – so I was actually started being trained as a neuropsychologist, but then found that I actually enjoyed doing therapy much more than doing assessments. And one of the things that I found surprising was that I was pretty convinced people were getting better [by] doing different types of therapies, but I wasn’t exactly convinced that of the reason why they were getting better. And there’s … I wouldn’t say, like, a lot of research, but there’s a lot of papers talking about things called “nonspecific factors.” And so these are things that, like, how the provider connects with the patient, or maybe instills hope, or manipulates expectations, that can impact the patient’s outcomes. And that’s regardless of the technique that you’re using. And those have been thought to account for a lot of the variance in how – at least in psychotherapy research – but they haven’t been studied very systematically yet – [so I] was always really interested in this – and then, can we find a way to actually study this?

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