What happens in our brain when we see the person we love? Why do we fall in love and stay with one person? What is the relationship between love and dopamine? These are some of the questions Helen Fisher and her colleagues set about asking in their 2005 fMRI study, “Romantic Love: An fMRI Study of a Neural Mechanism for Mate Choice.”
Background and Context
Falling in love is a universal human experience. The feeling of being in love might be the human experience we feel most strongly, besides perhaps grief. But why do we feel this romantic love so strongly? And what evolutionary purpose does this serve?
Some animals are polygamous – they have lots of different sexual partners throughout their lifetime. This could have an evolutionary advantage. Having lots of partners increases the chances of getting pregnant and having offspring.
But other animals are monogamous – they have one sexual partner. Humans, for the most part, are monogamous. This also has its evolutionary advantages. It might increase the chances of survival for the offspring, as having two parents provides more benefits for offspring. Dopamine is an important neurotransmitter that might help facilitate this monogamy. Fisher et al.’s study aimed to test their hypothesis that dopamine-rich areas of the brain are linked with being in love and this helps encourage monogamy.
- Key Study: Buss’ cross-cultural study on mate preference (1989)
- Key Study: Leading questions and the misinformation effect – ” the car crash study” (Loftus and Palmer, 1974)
- Key Study: Evolution of Gender Differences in Sexual Behaviour (Clark and Hatfield, 1989)
- Key Study: Emotion and Memory of a Baseball Game (Kensinger and Schacter, 2006)
Prior Research: Animal Studies
Studies investigating love and attraction often use prairie voles as they are primarily monogamous animals. One study showed that if dopamine levels were artificially increased in a female vole’s reward pathways, she would show a preference for a male who was present at the time of the increase in dopamine, even if she had not mated with that male previously. This suggests that dopamine can increase feelings of attraction for a particular individual and perhaps drive a desire towards procreating with that individual.
But this is voles. Could we expect the same results in humans? For ethical reasons, we can’t replicate the methodology used in the vole study above. Fisher et al. did the next best thing.
The researchers gathered a sample of 17 participants (10 females, 7 males) of an average age of 21 years old (range: 18 – 26). They collected their sample through word of mouth and by posting flyers asking for volunteers. All the participants were “in love” and the average age of courtship was 7 months (range: 1month – 17months). To determine the duration, intensity and nature of the participants’ romantic love, the researchers interviewed each participant using a semi-structured format and the participants also completed a “Passionate Love Scale (PLS)”.
The researchers found that using photographs of participants’ beloveds was an effective method for eliciting feelings of romantic passion, so they used these in their study. The procedure followed four steps:
- First, while in the fMRI, the participants were shown a photo of their beloved for 30 seconds.
- This was followed by a 40 second distraction task (counting backwards in 7s from a high number).
- Then a photo of an acquaintance was shown for 30 seconds.
- This was followed by a 20 second count-back task.
The duration of the fMRI scan was 12 minutes per participant, and afterwards the researchers found through interviews that during the time the participants were looking at a photo of their beloved they were engaging in romantic thinking and feeling.
The researchers also correlated the duration and intensity of the participants love and how this affected brain activity.
Results & Conclusions
Love and the Brain: The fMRI results showed that distinctly different parts of the brain were activated when the participants viewed photos of their beloveds versus acquaintances. When viewing photos of their beloveds, two areas of the brain known were activated. One area was the right ventral tegmental area (VTA), a dopamine-rich area of the brain and part of the brain’s “reward system”. Prior research has shown the VTA is an area of the brain associated with “pleasure, general arousal, focused attention and motivation to pursue and acquire rewards.” (Fisher, 2005). The right caudate nucleus was also activated. This part of the brain has been linked with detecting and expecting rewards.
These findings support the researchers’ hypotheses: romantic love is linked with dopamine-rich areas of the brain that are associated with reward and motivation. Thus, love is not an emotion, but rather romantic love is a motivation system that drives us towards being with the person we’re in love with. This can help facilitate monogamy as we feel pleasure when we’re with the same person, even if for long periods of time (e.g. months and years).
Localization: Another interesting finding was that the areas of the brain activated were different depending on the length of time the individual had been in love. Those in love longer also showed activity in other areas, like the anterior cingulate cortex (ACC) and the ventral pallidum. In studies on prairie voles, the ventral pallidum has been linked with attachment behaviours. The researchers suggest that perhaps the longer we’re with someone, the more the feeling of “love” shifts to parts of the brain associated with bonding and attachment to increase relationship security and to help with parenting.
Effects of Dopamine on Behaviour: The results also suggest that love is a drive, and as Pfaff says “all drives are associated with the activity of dopamine.” (cited in original). So we might conclude that the study shows how dopamine can influence our drive towards being in love.
But does this study suggest that dopamine increases feelings of love, or is it that the love increases the levels of dopamine? We can’t know for sure, but we can hypothesize using studies like those done on voles (see above).
IB Psych Exam Tip: I actually don’t recommend this study for IB Psychology students for exams. It’s quite difficult to explain carefully and clearly. While it’s related to the topics of neurotransmission, evolution, localization, brain imaging and personal relationships, explaining its relevance to these topics is very tricky.
Critical Thinking Questions
- Does this study suggest that love affects dopamine, or dopamine affects love?
- Why do dopamine levels increase when we see the person we are in love with?
- According to these studies, how can dopamine influence human behaviour?
- Why did they ask the participants to do the distraction task between photos?
- What are the limitations in applying results from this study to explain how dopamine can influence behaviour?
Fisher, Helen. Aron, Arthur. Brown, Lucy L. “Romantic Love: An fMRI Study of a Neural Mechanism for Mate Choice.” The Journal of Comparative Neurology. 493:58-62 (2005) (Accessed from interwileyscience.wiley.com) (Full study)
Updated Nov 2019
Travis Dixon is an IB Psychology teacher, author, workshop leader, examiner and IA moderator.