Last of the 2022 Research

My plan is to finish up here telling you about the research done in 2022.  In the future I will just choose one new study and write about what it brings up for me to talk to you about it.  

So as promised, here are the last good studies of 2022. I know some of you will be fascinated, some bored.  Remember, you can always just read the title and “bottom line.”  Above all, be happy with all the research being done, putting us on the scientific map!

1. Sensory processing sensitivity (SPS) and axonal microarchitecture: identifying brain structural characteristics for behavior. 

David, S., Brown, L. L., Heemskerk, A. M., Aron, E., Leemans, A., & Aron, A. (2022). Sensory processing sensitivity and axonal microarchitecture: identifying brain structural characteristics for behavior. Brain Structure and Function, 1-17.

This study is another example, using totally different methods, of how much the brains of those high in SPS (people who are HSPs) differ from those low in the trait.  Previous research on the brain and SPS has mostly used functional magnetic resonance imagining (fMRI), but this study used a new method, diffusion tensor imaging (DTI, measuring diffusion of water in the axon) to look for “axonal microstructural differences,” which are differences in the arrangement of white matter in the brain, telling us something about how the brain is organized while it is at rest, not doing anything.

We had available 408 participants from the Human Connectome Project. Also known as the Young-Adult Human Connectome Project, the National Institute of Health created this free data bank to obtain a map of the normal brain by doing DTIs on 1200 young, healthy subjects, plus having them take many psychological tests, and making all this data available for research.  Of course, the participants in the Human Connectome Project did not take the HSP Scale, so we had to create a “proxy” SPS questionnaire using individual questions from other questionnaires they had taken that seemed by their contents to measure SPS.  (This “proxy” HSP measure was first given along with the HSP Scale to a large number of people, and only the items correlating best to the HSP Scale were used in the final proxy measure.)

The results?  The differences between HSPs and those without the trait in the microstructure of their white matter in specific cortical regions were consistent with what had been found in fMRI studies, although there were a few new areas with differences that related to attention and cognitive flexibility, empathy, emotion, and first levels of sensory processing, as in the primary auditory cortex—all differences you would predict given what we know about HSPs.

Bottom Line: Once again, SPS is shown to be a real trait, in that those with it have brains that look and perform differently than the brains of those who do not have the trait.  Can’t be simpler.

2. Emotional Contagion and Mirror System Activity in the Highly Sensitive Person.

Ishikami, Y., & Tanaka, H. (2022). Emotional Contagion and Mirror System Activity in the Highly Sensitive Person. In International Symposium on Affective Science and Engineering ISASE2022 (pp. 1-4). Japan Society of Kansei Engineering.

Understanding that HSPs are thought to have more empathy but that questionnaires about one’s empathy can be inaccurate, the authors evaluated empathy in two ways that did not require asking people with questionnaires.  The first used an electroencephalograph (EEG) to measure mirror system activity (indicating a particular aspect of empathy).  The second method looked for emotional contagion (another kind of empathy).

In the study of mirror neurons, participants were shown a video of someone raising a cup.   While watching the cup being raised, participants with an HSP Scale score of 100 or higher showed “event-related desynchronization of 50% or higher,” indicating that they were having greater mirror system activity (or mentally mirroring the video) in response to someone else’s movements.

In the study of emotional contagion, when people looked at an image of a happy face, those with higher HSP Scale scores showed lower alpha wave activity in their brains. Since alpha waves are associated with non-arousal, it was inferred that the happy face created happy feelings, which increased HSPs’ arousal and reduced their alpha rhythms. Interestingly, neutral or sad faces did not. 

Thus, it was found in these two studies that the higher the HSP Scale score, the greater the level of mirror system activity and of emotional response to seeing someone looking happy, all of which indicates greater empathy without using questionnaires to ask about it.

Bottom Line: Once again a brain measure finds what questionnaires have also shown:  In this case that we have more empathy and a greater positive response to positive emotions in others.

3. Variability in the Relationship Between Parenting and Executive Functions in Early Childhood: The Role of Environmental Sensitivity.

Oeri, N. S., Kunz, N. T., & Pluess, M. (2022). Variability in the Relationship Between Parenting and Executive Functions in Early Childhood: The Role of Environmental Sensitivity. OSF Preprints

Executive functioning refers to the ability to plan, focus attention, remember an instruction, or multitask when necessary.  Very poor executive functioning is the same as Attention Deficit Disorder.  In this study, executive functioning was higher for HSCs whose parents reported more involved parenting, while it was substantially lower for HSCs whose parents reported using corporal punishment. No such effects emerged for less sensitive children.  This is a straightforward case of differential susceptibility.

Bottom Line:  This is just what we would expect:  A child who is over aroused all the time, fearing punishment, will not be able to develop executive functioning as well as a child who feels supported and securely attached to parents and can focus their attention on what they are doing.

4. The relation between sensory processing sensitivity and telomere length in adolescents.

Jentsch, A., Hoferichter, F., Raufelder, D., Hageman, G., & Maas, L. (2022). The relation between sensory processing sensitivity and telomere length in adolescents. Brain and Behavior, 12(9), e2751.

Telomeres are repeated DNA sequences located at the ends of chromosomes, and their length reduces naturally over time, so telomere length (TL) is considered a biomarker of cellular aging.  But stress and certain personality traits are associated with shorter TL as well.  Its meaning is really not well studied in young people, but in a study of 82 healthy adolescents aged 13–16 from secondary schools in Germany, students with higher scores on the HSP Scale were likely to have shorter telomeres.  TL could be associated with simply having the trait, but if stress is the cause, well, we know HS adolescence in public schools are certainly under stress.

Bottom Line: This may mean we need to improve the lives of HS high school students, which we should do anyway.

5. Investigating the relationship between sensory processing sensitivity and relationship satisfaction: Mediating roles of negative affectivity and conflict resolution style.

Zorlular, M., & Uzer, T. (2022). Investigating the relationship between sensory processing sensitivity and relationship satisfaction: Mediating roles of negative affectivity and conflict resolution style. Current Psychology, 1-10.

This study looked at 200 Turkish couples age 18-25 in romantic relationships (not married or living together) for at least 24 months.  The authors emphasized that HSPs tended to have less satisfying relationships if they displayed a tendency to have negative emotions or poor conflict resolution skills and those high in SPS tend to have more negative emotions.  But they did not point out that if you statistically control for negative emotions—that is, hold it to be the same in everyone—there is no correlation between SPS and relationship dissatisfaction or satisfaction.  (They also looked at the effect of one’s childhood and found no relationship with SPS and satisfaction, but it was not a good measure of childhood.)

Bottom Line: We can imagine many reasons why HSPs in a relationship might be negative and also dissatisfied with it. But this study is clear that just being an HSP does not interfere with being happy in a relationship.

6. Environmental Sensitivity in Adults: Psychometric Properties of the Japanese Version of the Highly Sensitive Person Scale 10-Item Version.

Iimura, S., Yano, K., & Ishii, Y. (2022). Environmental Sensitivity in Adults: Psychometric Properties of the Japanese Version of the Highly Sensitive Person Scale 10-Item Version. Journal of Personality Assessment, 1-13.

The important part of this study was not revealed in its title:  In order to show that their 10-item scale was valid, in the last of a series of four studies reported in the article they showed a short positive video to the study participants (85 Tokyo college students) and then gave them a measure of how happy or sad they felt.  Only those high on the HSP Scale had more positive feelings after watching the video, an example, according to the authors, of vantage sensitivity.

Bottom Line: In spite of all the talk about our negative emotions and tendency to neuroticism, on average we enjoy positive experiences more than others do!