Short alleles, bigger smiles? The effect of 5-HTTLPR on positive emotional expressions

Claudia M. Haase, Ursula Beermann, Laura R. Saslow, Michelle N. Shiota, Sarina R. Saturn, Sandy J. Lwi, James J. Casey, Nguyen K. Nguyen, Patrick K. Whalen, Dacher Keltner, Robert W. Levenson*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


The present research examined the effect of the 5-HTTLPR polymorphism in the serotonin transporter gene on objectively coded positive emotional expressions (i.e., laughing and smiling behavior objectively coded using the Facial Action Coding System). Three studies with independent samples of participants were conducted. Study 1 examined young adults watching still cartoons. Study 2 examined young, middle-aged, and older adults watching a thematically ambiguous yet subtly amusing film clip. Study 3 examined middle-aged and older spouses discussing an area of marital conflict (that typically produces both positive and negative emotion). Aggregating data across studies, results showed that the short allele of 5-HTTLPR predicted heightened positive emotional expressions. Results remained stable when controlling for age, gender, ethnicity, and depressive symptoms. These findings are consistent with the notion that the short allele of 5-HTTLPR functions as an emotion amplifier, which may confer heightened susceptibility to environmental conditions.

Original languageEnglish (US)
Pages (from-to)438-448
Number of pages11
Issue number4
StatePublished - Aug 1 2015


  • 5-HTTLPR
  • Differential susceptibility
  • Genetic polymorphisms
  • Positive emotional expressions

ASJC Scopus subject areas

  • General Psychology


Dive into the research topics of 'Short alleles, bigger smiles? The effect of 5-HTTLPR on positive emotional expressions'. Together they form a unique fingerprint.

Cite this