Serotonin and Sexual Orientation (Liu et al., 2011)
- Aim: Is serotonin related to sexual preference in rats?
- Method: Male mice were genetically manipulated to have a gene that produced normal amounts of serotonin or low amounts of serotonin
- The independent variable was whether the mice got manipulated to have a low or normal serotoning producing gene
- They placed the manipulated mice in cages with other male mice and/or female mice
- The dependent variable was which sexes the male mice chose to mount
- Results: Normal serotonin males mounted females 60-80% of the time and mounted males 20% of the time
- Low serotonin males lost their sexual preference for females and mounted both males and females equally 80% of the time
- Conclusion: Serotonin affects sexual preference in rats such that low serotonin mice become more bisexual than normal serotonin rats
- Evaluation: Cannot generalize these findings to humans and it would be unethical to genetically manipulate humans to test for the chemical roots of sexual preference
- What about female rats? Only male rats were used in this study
Here are some videos of the rats in Liu's study
Normal serotonin male chooses a female over a male - hetero rat
Low serotonin male mounts a male - homo rat?
Low serotonin male mounts both male and female - bisexual rat?