Love as Conditioned Reward and Motivation

The doctor enters her husband’s warm colored office. He sits hunched over a computer, typing away. The doctor hears the constant thudding of the mouse as she nears her husband’s desk. “Guess what?” she asks. He turns around, smiles at his wife’s dropping eyelids, and answers “what?” The doctor grabs his hand and says, “I love you.” He feels rewarded by the interaction and embraces his wife. “I love you, too.” 

The interaction is repeated constantly in the following years, always beginning with a muttered “guess what?” One day, the scene unfolds again: The doctor enters her husband’s office. “Guess what?” she asks. Now, used to the interaction, her husband feels a pre-emptive sense of reward. Before she can say anything else, he gets up from his chair, embraces his wife, and answers, “I love you, too.” 

Amber Baillie published this incident as a blog post titled, “I unintentionally classically conditioned my husband.” Goldstein, the original writer, had first published the story in a journal of cognitive psychology. According to Goldstein, the repeated pairing of specific stimuli prompted her husband to associate love and intimacy with the phrase “guess what?” 

In more depth, the link between different stimuli in the couple’s interactions supported feelings of reward, through the secretion of the neurotransmitter dopamine in the process of synapses. 

Dopamine, Love and Reward  

A synapse occurs when two neurons link to one another and exchange neurotransmitters. Neurotransmitters are chemical signals that transmit information to an immediate nerve cell, muscle cell, or gland. If we take communication theory as an example, neurons act as the sender, the synapses as the channel, the immediate cells as the recipient, and the neurotransmitters as the message. 

Source: The Brain from Top to Bottom (McGill, n.d.). 

Dopamine neurotransmission occurs as a result of the synapses between a neuron and an adjunct cell. 

Dopamine is a neurotransmitter that plays a role in feelings of pleasure, motivation, and reward. Neurons secrete dopamine in the processes of learning, remembrance, focus, arousal, and sleep. Thus, the continuous secretion of dopamine strengthens synapses between different stimuli, reinforcing positive emotions and memories. In other words, the constant secretion of dopamine made the doctor’s husband create a mental association between the phrase “guess what?” and the word “love.” 

An experiment by Aron and colleagues set out to find the correlation between dopamine-induced rewards and feelings of romantic love. The researchers tested two hypotheses with the aid of functional MRI (fMRI), an imaging method that shows changes in the brain. The first hypothesis was that romantic love would activate brain regions involved in reward systems and dopamine secretion, such as the ventral tegmental area (VTA) and the nucleus accumbens. The second hypothesis was that romantic love would activate other reward systems like the anterior caudate nucleus, which are involved in goal setting and in detecting expectations for rewards. 

Your Brain in Love 

To test the brain regions activated in the reward processes, the researchers recruited ten women and seven men from New York State University, ages eighteen to twenty-six, who reported feeling intense love towards their partner. Before the fMRI session, participants completed an interview and two questionnaires about their specific feelings and their romantic relationship. 

For the subsequent scanning session, each participant provided a photograph of their partner as positive stimulus, plus a “similar photograph of a familiar, emotionally neutral acquaintance of the same age and sex as the beloved,” for a neutral stimulus. Then, the researchers projected the images. They asked participants to think about positive memories with their partners, and to think about neutral events that happened with their acquaintance, when observing the respective pictures. Participants chose these memories beforehand, at the initial interview. 

As predicted, the fMRI depicted significant more activation in brain regions that are dopamine rich –or associated with motivation-reward systems– when participants looked at their loved one, versus when they looked at a neutral person. A similar experiment by Takahashi, depicted higher dopamine levels and physical excitement when researchers triggered feelings of attachment, reward, and pair bonding towards the participant’s loved ones. 

Source: MIT News (Trafton, 2020). 

An fMRI of the brain shows higher activation of regions related to dopamine secretion, when participants looked at pictures of their beloved versus when they looked a pictures of acquintences. 

Romantic Love as a Motivation State 

In their experiment, Aron and colleagues concluded that “intense romantic love is associated with reward and goal representation regions, and that rather than being a specific emotion, romantic love is better characterized as a motivation or goal-oriented state.” This reframing of love as a so-called motivation state can explain why people usually want to spend time with and to protect their loved one. 

Berridge supports the idea of love as motivation, attributing incentive salience to reward stimuli. Incentive salience means the motivation for rewards, or attention-grabbing wants, as the result of previously learnt associations. In other words, dopamine neurotransmission is associated with this feeling of “wanting something.” Incentive salience is the result of a connection –often experienced in classical conditioning– between a cue like your spouse asking “guess what?” and its reward, hearing them say “I love you.” 

In this sense, it is not far-fetched for Goldstein to claim that she unwittingly classically conditioned her husband. However, the reason why he responded, “I love you, too” when asked “guess what?” is not only because he learnt to associate the two stimuli. The other reason is that the cue of seeing his wife created an influx of dopamine. Then, the reward of hearing “I love you” by his beloved activated the husband’s want to spend time with Goldstein, and motivated him to protect his relationship. And so, he responded, “I love you, too.” 

Sources

Baillie, N.B. (2014, December 9). I Unintentionally Classically Conditioned my Husband. Penn State. https://sites.psu.edu/psych256fa14/2014/12/09/i-unintentionally-classically-conditioned-my-husband/ 

Berridge, K.C. (2006). The Debate Over Dopamine’s Role in Reward: The Case for Incentive Salience. Psychopharmacology 191, 391-431. https://link.springer.com/article/10.1007/s00213-006-0578-x 

Cleveland Clinic Medical Professional. (2022, March 14). Neurotransmitters. Cleveland Clinic. https://my.clevelandclinic.org/health/articles/22513-neurotransmitters#:~:text=What%20are%20neurotransmitters%3F,muscle%20cell%20or%20a%20gland 

McGill. (n.d.). The Role of Dopamine [Photograph]. The Brain from Top to Bottom. Retrieved from https://thebrain.mcgill.ca/flash/i/i_03/i_03_m/i_03_m_que/i_03_m_que.html 

Takahashi et al. (2015). Imaging the Passionate Stage of Romantic Love by Dopamine Dynamics. Frontiers in Human Neuroscience. https://www.frontiersin.org/articles/10.3389/fnhum.2015.00191/full 

Trafton, A. (2020). How Dopamine Drives Brain Activity [Photograph]. MIT News. Retrieved from https://news.mit.edu/2020/dopamine-brain-activity-mri-0401 

Zhang et al. (2009). A Neural Computational Model of Incentive Salience. PLOS Computational Biology. https://journals.plos.org/ploscompbiol/article?id=10.1371/journal.pcbi.1000437