The broaden-and-build theory of positive emotions was developed to explain why people experience positive emotions. What purpose might be served by fleeting feelings of joy, gratitude, serenity, or love? Did such pleasant states confer adaptive value over the course of human evolution?
Within prior theories of emotions, positive emotions posed a puzzle. This was because most prior accounts rested on the assumption that all emotions— both pleasant and unpleasant—were adaptive to human ancestors because they produced urges to act in particular ways, by triggering specific action tendencies. Fear, for instance, is linked with the urge to flee, anger with the urge to attack, disgust the urge to expel, and so on. A core idea within the concept of specific action tendencies is that having these particular actions spring to mind made emotions evolutionary adaptive because such quick and decisive actions helped early humans to survive specific threats to life or limb. Another core idea is that specific action tendencies are embodied thoughts: Ss they overtake conscious thought, they also trigger rapid bodily changes that support the actions called forth. If you, at this moment, saw danger looming and were experiencing fear, you would not only experience an overwhelming urge to flee to safety, but also within milliseconds your cardiovascular system would have switched gears to redirect oxygenated blood to large muscles so that you’d be physically ready to run away. The major contribution made by the concept of specific action tendencies, then, was to explain why emotions infuse both mind and body and how the forces of natural selection might have shaped and preserved emotions as part of universal human nature.
The trouble with the concept of specific action tendencies came when past theorists tried to pinpoint the tendencies sparked by positive emotions. Joy had been linked to the urge to do anything, and serenity with the urge to do nothing. Not only were these urges vague and nonspecific, it’s doubtful whether doing nothing is an action at all! Positive emotions, then, did not fit the theoretical mold that worked so well for negative emotions. Noticing this puzzle and other intriguing features of positive emotions, Barbara L. Fredrickson offered the broaden-and-build theory to explain the evolved adaptive significance of positive emotions.
The broaden-and-build theory holds that, unlike negative emotions, which narrow people’s ideas about possible actions (through specific action tendencies), positive emotions broaden people’s ideas about possible actions, opening their awareness to wider ranges of thoughts and actions than are typical for them. Joy, for instance, sparks the urge to play and be creative, interest sparks the urge to explore and learn, and serenity sparks the urge to savor current circumstances and integrate them into new self-views and worldviews.
Whereas the narrowed mindsets sparked by negative emotions were adaptive in instances that threatened survival in some way, the broadened mindsets sparked by positive emotions were adaptive in different ways and over longer time scales: Broadened mindsets were adaptive because, over time, such expansive awareness served to build humans’ resources, spurring on their development, and equipping them to better handle sub-sequent and inevitable threats to survival.
To illustrate, consider the playful mindset sparked by joy. Ethological research documents that as complex organisms play with conspecifics, they forge social alliances (i.e., friendships). In times of trouble, these gains in social resources might spell the difference between life and death. Consider also the urge to explore novel environments sparked by interest. Behavioral research documents that positive and open mindsets—because they yield exploration and experiential learning—produce more accurate cognitive maps of the local environment, relative to negative and rejecting mindsets. Such gains in intellectual resources might again spell the difference between life and death in certain circumstances.
The broaden-and-build theory states that positive emotions were adaptive to one’s human ancestors because, over time, positive states and their associated broadened mindsets could accumulate and compound in ways that transformed individuals for the better, leaving them with more social, psychological, intellectual, and physical resources than they would have otherwise had. When these ancestors later faced inevitable threats to life and limb, their greater resources would have translated into better odds of survival and of living long enough to reproduce. To the extent that the capacity to experience positive emotions was genetically encoded, this capacity would have been shaped by natural selection in ways that explain the form and function of the positive emotions that modern-day humans experience.
Since its inception, the broaden-and-build theory has been tested and supported by a wide range of empirical research. Controlled laboratory experiments document that, compared to neutral and negative states, induced positive emotions widen the scope of people’s attention, expand their repertoires of possible actions, and create openness to new experiences. Prospective field studies show that people who, for whatever reasons, experience more positive emotions than others are better equipped to deal with life’s adversities and challenges. Last but not least, randomized controlled tests of interventions designed to augment people’s positive emotions—like practicing meditation or cultivating the habit of counting blessings—have documented that these interventions build people’s enduring resources, including immune functioning, mindfulness, and relationship closeness.
At a practical level, the broaden-and-build theory gives modern-day humans reason to cultivate and cherish positive emotions. Pleasant states like joy, interest, serenity, gratitude, and love do not merely feel good in the moment, but they also place people on trajectories toward positive growth: As these positive emotions accumulate and compound, they pave the way for people to reach their higher ground: to become healthier, more knowledgeable, more resilient, and more socially integrated versions of themselves.
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