Retraining reactions to smells
Principal Investigator: 

Wen Li

Norman B. Schmidt, Ph.D.

Florida State University


One of the major factors that has been found to contribute to suicide risk is a pattern of experiencing feelings of anxiety. A well-known example is that Veterans with post-traumatic stress disorder (PTSD) are at a higher risk of suicide than other Veterans. Thus it makes sense that if ways could be found to help Veterans reduce feelings of anxiety, it could also reduce suicide risk in those Veterans. And this is exactly what Wen Li and Brad Schmidt, psychology researchers at Florida State University, have set out to do, focusing on helping Veterans and others learn to handle anxiety-causing smells.

Many Veterans, particularly those with PTSD, are distressed by certain smells, such as those of burning rubber, gunpowder, and various flammable liquids. One study found, for instance, that 93 percent of combat Veterans with PTSD reported being distressed by the smell of burning rubber.

A major problem with many of these Veterans, Li explains, is that they are highly sensitized to these smells and that even of whiff of a particular odor is enough to trigger anxiety. Someone who is highly sensitive to the smell of gasoline, for example, might become distressed by coming close to someone who had just filled up his car’s gas tank, even if the gas odor was so slight that most people wouldn’t even notice it. The regular anxiety episodes caused by such a sensitivity can be very distressing.

Thus Li and Schmidt have set out to use a technique called “perceptual retraining” to help Veterans and others reduce their sensitivities to such odors. The idea behind the retraining is that people with such sensitivities are not drawing a distinction between a very slight smell, which is unlikely to signal the presence of a problem, and a strong smell, such as from a large gasoline leak, which could indeed indicate some sort of danger.

“PTSD patients,” Li says, “can’t differentiate between a minimum-level smell and a threat-level smell. They see a little bit of ‘red’ in everything. They pay attention to the small amount of red signal, while in healthy controls this will be dismissed. We want to train them to dismiss this small amount of threat signal while maintaining their ability to detect something that is truly a threat.”

Li has previously used perceptual retraining to help people with social anxieties improve their ability to read emotions on other people’s faces. Social phobics are much more sensitive that other people to signs of anger in a person’s face and will report a face as angry that others see as neutral. The retraining involves showing the social phobic different faces showing a spectrum of expressions from neutral to angry—with the faces generated with a morphing program with a neutral face on one end and an angry face on the other—and asking the person to identify the emotion. The subject gets immediate feedback—yes, that’s right, or no, that’s not right—and within a relatively short time learns to identify the truly angry faces from the ones that are mostly neutral.

To help Veterans that respond anxiously to certain smells, Li has developed a variation on this approach that is designed to work with odors. It is based on a similar “morphing” technique, except in this case is it odors and not faces that are being morphed. By mixing, say, gasoline into a neutral-smelling liquid such as anisole, which smells something like anise seed, she can produce a range of odors, from those that have a very faint gasoline smell to those that smell strongly of gasoline. With that she can train people who are sensitized to the smell of gasoline to distinguish between mostly neutral smells with just a hint of gasoline and those that truly do smell of gasoline. The purpose of the training, Li says, is to create “a psychological distance between a minimal, insignificant signal and a real signal.”

As of the end of 2016, Li had completed the odor perceptual retraining in four people, each of whom had been found to have heightened sensitivities to the sorts of smells that service members experience during deployment—in particular, burning rubber, gunpowder, and gasoline. She had hoped to enroll more subjects by that point, she said, but the protocols are time-intensive, and her funding came through relatively late in the consortium’s first phase of the consortium. Although the project was funded only through August 2016, Li is working on a no-cost extension, and in the remaining eight months of that extension she is hoping to enroll more subjects and accumulate more data for her analysis.

After that, Li says, she hopes to use the current study as a pilot project to serve as the basis for a longer, better funded study, assuming the initial results are promising. Ultimately, of course, the goal is to add another tool to the kit of psychologists and therapists working to reduce the risk of suicide among Veterans.

No news on file at this time.