Danner, D. D., Snowdon, D. A., & Friesen, W. V. (2001). Positive emotions in early life and longevity: Findings from the nun study. Personality  Processes and Individual Differences, 80(5), 804-813. doi: 10.1037/0022-3514.80.5.804.

180 Catholic nuns were followed from early life (mean age of 22) to late life (ages 75 to 95). At the mean age of 22, the handwritten autobiographies of the sample were scored for emotional content. During late life, the nuns were annually assessed for physical and cognitive function, with a mean age at the first assessment of 83. Those who showed the most positive emotion in their autobiographies composed at the mean age of 22 had a much less risk of mortality than those who showed the least.  25% more survived to the age of 80, and for every 1% increase in the number of positive-emotion sentences there was 1.4% decrease in mortality rate.


Fredrickson, B. L. (1998). What good are positive emotions? Review of General Psychology, 2, 300-319.

Fredrickson offers her broaden and build theory on the eve of the new millennia, arguing that positive emotions have been neglected in traditional psychology. This is due to the lack of problems positive emotions cause, with the problems from negative emotions demanding attention. Fredrickson affirms that positive emotions can provide important solutions to these problems created by negative emotions. Moreover, that there are fewer positive emotions with empirical grounding, and that these are less differentiated than their negative counterparts leading them to receive less attention in the research community. Fredrickson details the specific roles of the positive emotions of joy, interest, contentment, and love, as providing important functions for our development of resources. Empirical evidence to support the broaden and build theory is presented.


Fredrickson, B. L. (2001). The role of positive emotions in positive psychology: The broaden-and-build theory of positive emotions. American Psychologist, 56(3), 218-226. doi: 10.1037/0003-066X.56.3.2

Barbara Fredrickson, in her seminal article in the American Psychologist presents her theory behind the role of positive emotion. She argues that like negative emotions, positive emotions serve a vital role in our development and existence, they don’t just make us feel good. In experiencing positive emotions, we perform behaviours that generate intellectual, physical, social, and psychological resources that increase our repertoires of thoughts and actions available to us as we interact with the world and those within it. Positive emotions broaden the ways we can think and behave, and in doing so allows us to cope and survive in our world through the resources we develop.


Fredrickson, B. (2009). Positivity: Groundbreaking research to release your inner optimist and thrive. London: Oneworld.

In this more accessible title, Fredrickson presents the role of positive emotions alongside the broaden and build theory, adapted for a wider audience. Topics are presented and discussed such as the positivity ratio, the importance of increasing positivity and maximising (not eliminating) negativity. As well as drawing on a wealth of positive psychology literature to present ways to cultivate positivity in yourself and those you interact with.


Fredrickson, B. L., & Levenson, R. W. (1998). Positive emotions speed recovery from cardiovascular sequelae of negative emotions. Cognition and Emotion, 12(2), 191 – 220. doi: 10.1080/026999398379718.

In two studies, Fredrickson and Levenson tested the hypothesis that positive emotions can contribute towards our speed of recovery from negative cardiovascular effects associated with negative emotions. Study 1 featured 60 female undergraduate students. Participants watched a fear inducing film clip followed by a positive, neutral, or negative emotion inducing film. Their facial behaviour, upper body movement, and cardiovascular system were monitored throughout. Participants who viewed the positive films after the fear inducing film had their cardiovascular activation return to what it was prior to the fear inducing film faster than those who watched the negative or neutral film. In study 2, an all Caucasian, male and female sample between the ages of 20 and 25 were paid £25 to participate. Participants again viewed the same fear-inducing film, followed this time by a sad funeral film for all participants. Those who smiled at least once whilst viewing the sad film returned to their pre-fear film cardiovascular activation faster than those who did not smile at all.


Fredrickson, B. L., Mancuso, R. A., Branigan, C., &Tugade, M. M. (2000).The undoing effect of positive emotions. Motivation and Emotion, 24(4), 237 – 258. doi: 10.1023/A:1010796329158.

In a further two studies, 170 male and female university students had anxiety induced and thus the negative cardiovascular reactivity to this anxiety, followed by a film selected to elicit positive or negative emotions, or a neutral film. Those viewing the positive films designed to elicit amusement and contentment recovered from the negative cardiovascular effects of anxiety faster than those who had watched a negative emotion or neutral film. The second study examined 185 students paid $30 to participate and followed the same anxiety inducing procedure as study 1. However, all participants then watched a neutral film. Findings suggest support for the undoing hypothesis.


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