Contributed by Jennifer Ouyang, SASSC Undergrad Member-At-Large
2024 Best Dissertation in Affective Science Award Winner Dr. Anthony Gianni Vaccaro
Imagine that you are back in time, going through a major life transition, such as high school graduation. It was a period when you experienced many conflicting feelings all at once. You might have felt excited about college life in a few months, but also sentimental about separating from your best friends at home. These mixed feelings, often termed ambivalence, are a universal yet underexplored aspect of human emotion. Dr. Anthony Vaccaro, winner of the 2024 Best Dissertation in Affective Science award, digs into the neurobiological underpinnings of these complex emotional experiences. Dr. Vaccaro’s research in this area was inspired by his love for musical theater and cinema, where characters often grapple with multifaceted and opposing emotions during pivotal moments. How, he wondered, do these episodes play out in the brain?
In his first chapter, “Bittersweet: The Neuroscience of Ambivalent Affect”, Dr. Vaccaro sets the stage for the rest of his research by providing a conceptual and neurobiological framework for mixed feelings (Vaccaro et al., 2020). In this framework, emotions are defined as physiological changes triggered by stimuli (Damasio, 2018; Damasio & Carvalho, 2013), while feelings are the conscious experience of these changes. The positive, negative, or ambivalent character of both types of affective states is defined as valence. These distinctions are crucial as they underpin the study of ambivalent affect and highlight the layered complexity of our emotional experiences.
Dr. Vaccaro then proposes two mechanisms for ambivalent affect:
- Rapid vacillation: Quick alternations between positive and negative emotions, coordinated by brainstem nuclei.
- Simultaneity: Positive and negative affect are processed simultaneously at different neural levels. Subcortical structures trigger emotions, while the cortical level processes them into feelings.
These mechanisms are both thought to play a role in the generation of seemingly paradoxical feelings. Reviewing existing research, Dr. Vaccaro describes how rapid vacillation and simultaneity could work together to bring about ambivalent affect. At the subcortical level, emotional action programs are coordinated by brainstem nuclei, which prevent simultaneous opposite emotions but allow fast switching between positive and negative valenced states. The insular cortex then integrates these states across time, resulting in the experience of a single ambivalent feeling. The evidence to date supports this proposal: Lower brain regions and the insular cortex show consistent and distinguishable neural patterns for positive and negative feelings, but not for mixed feelings. Instead, in higher brain regions such as the anterior cingulate cortex (ACC) and frontal cortex, mixed feelings manifest as unique and consistent neural patterns that are distinct from ‘pure’ positive or negative states. These findings suggest a neural distinction between subcortical and cortical processes, with higher cortical regions specifically involved in the integration and representation of complex emotional states, including ambivalent feelings.
Dr. Vaccaro also points out that ambivalent affect often involves memory and counterfactual thinking — for instance, nostalgia evokes positive memories that trigger negative emotions upon reappraisal. Dr. Vaccaro holds that these processes are crucial for experiencing ambivalent affect and likely explain its late developmental emergence compared to other ‘simpler’ emotional states. Drawing on child development data, Dr. Vaccaro notes that younger children typically report experiencing one feeling at a time, while older children can perceive and report ambivalent emotions. Dr. Vaccaro further explains that the ability to experience ambivalent affect develops alongside certain neural pathways and becomes crucial during young adulthood when individuals face complex life transitions. Brain regions like the orbitofrontal cortex (OFC) and ACC are involved in processing the perception of conflict. The ACC monitors conflict while the OFC evaluates affective states, contributing to the unique experience of mixed emotions—more than just the sum of positive and negative experiences.
When talking to Dr. Vaccaro, he specifically mentions the need to improve the methodology of investigating ambivalent affect. “The most important thing, which is very basic, is that we can’t study what we don’t measure. We can’t study mixed feelings easily when the most dominant methods we use to measure affect are bipolar scales. As we’re moving towards big data and open science where we can collect lots of data and share it with everyone, it’d be really important to make sure that our emotion measures can actually capture mixed feelings,” he said.
Understanding ambivalent affect can lead to better therapeutic approaches for mental health issues where mixed feelings are significant. For example, major life transitions are often accompanied by both excitement and anxiety. Developing strategies that validate these feelings may foster resilience and help manage the sense of uncertainty. Dr. Vaccaro’s work suggests that ambivalence is a natural and valuable part of human life, and it is important for us to embrace the complexity of our emotions.
References
Vaccaro, A. G., Kaplan, J. T., & Damasio, A. (2020). Bittersweet: The Neuroscience of Ambivalent Affect. Perspectives on Psychological Science, 15(5), 1187–1199. https://doi.org/10.1177/1745691620927708
Damasio, A. (2018). The strange order of things: Life, feeling, and the making of cultures. New York, NY: Pantheon.
Damasio, A., & Carvalho, G. B. (2013). The nature of feelings: Evolutionary and neurobiological origins. Nature Reviews Neuroscience, 14, 143–152. doi:10.1038/nrn3403