Positive Psychology Progress: Empirical Validation of Interventions

positive psychology progress
Progress in Positive Psychology. Image Retrieved by URL.

Martin Seligman and his colleagues Steen, Park, and Peterson wrote the 2005 article “Positive Psychology Progress: Empirical Validation of Interventions,” a central publication in positive psychology literature. It offers a review of the developments in the field between 2000 and 2005.

The article includes a review of the growth observed in positive psychology, research into whether people can become lastingly happier, and the results of happiness interventions.

What follows is a summary of the article with its key aspects and findings.

“As for the future, it remains unwritten. Anything can happen, and often we are wrong. The best we can do with the future is to prepare and savor the possibilities of what can be done in the present.”

– Todd Kashdan



Introduction to the Field

“The value of the overarching term ‘positive psychology’ lies in its uniting of what had been scattered and disparate lines of theory and research about what makes life most worth living” (Seligman, Steen, Park, & Peterson, 2005).

The American Psychologist issue published in the year 2000 was entirely devoted to positive psychology. It marked the emergence of science dedicated to the study of positive emotions, positive character, and positive institutions.

Positive psychologists study mental health and well-being, deploying the same methods used to effectively study mental disorders. Positive psychology’s roots trace back to the works of Rogers, Maslow, Jahoda, Erikson, Vaillant, and Deci and Ryan, among many others.

Positive psychology researchers didn’t invent the good life or pioneer its scientific study. What positive psychology did was create a framework for a body of research and a theory about what makes life worth living that didn’t exist before.

As the science of positive psychology rapidly moves forward, the question becomes, Can psychologists take what they learned from the science and practice of treating mental illness and use it to create a practice of making people lastingly happier?


Progress in Positive Psychology

Positive psychology is a broad term used to describe the study of positive emotions, positive traits, and positive institutions. It doesn’t replace the scientific understanding of mental disorders but instead complements it to achieve a more complete picture of human experience, one that captures both the ups and the downs of life.

A complete psychological science should include an understanding of both suffering and happiness and how the two interact, therefore validating interventions that both relieve suffering and increase happiness, which are distinct tasks.



Between 2000 and 2005, the number of articles about positive psychology in scholarly and popular press escalated rapidly. So did the number of books published about the topic, including the following:


Character Strengths and Virtues

Character Strengths and Virtues: A Handbook and Classification by Martin Seligman and Christopher Peterson (2004), known as the CSV, was the result of an ambitious endeavor to describe and classify human strengths and virtues that enable individuals to flourish.

This systematic approach to positive traits aimed to do for well-being what the Diagnostic and Statistical Manual of Mental Disorders (DSM) does for psychological disorders: develop a common language for psychologists around the world.

One point that Seligman and Peterson make clear is that these positive traits are regarded as individual differences that exist in degrees instead of all-or-nothing categories.

The structure of the CSV relies on 6 virtues that are endorsed and valued across almost all cultures worldwide:

  • Wisdom;
  • Courage;
  • Humanity;
  • Justice;
  • Temperance;
  • Transcendence.


Under each of these virtues fall 24 character strengths, which meet criteria such as being ubiquitous, fulfilling, morally valued, trait-like, etc.

Each chapter of the CSV describes what is and isn’t known about each strength, including paradigm cases, consensual definitions, historical and cross-cultural backgrounds, enabling and disabling conditions, gender differences, interventions that build that strength, and more.

Three interesting findings emerged.

The first is a remarkable resemblance in the endorsement of character strengths by adults around the world. The most common ones in 40 different countries are:

  • Kindness;
  • Fairness;
  • Authenticity;
  • Gratitude;
  • Open-mindedness.


The least common ones are:


The second interesting finding is that comparing the strengths profiles of U.S. adults and adolescents reveals a general agreement on ranking, but that they still agreed less than U.S. adults did with adults of other countries.

Hope, teamwork, and zest were more commonly valued by U.S. youths than their adult compatriots. Appreciation of beauty, authenticity, leadership, and open-mindedness were more commonly valued by adults.

These results suggest that we should be as concerned with preventing certain strengths from eroding as we grow older as we are with building strengths.

The third interesting finding is that it seems that strengths “of the heart” like zest, gratitude, hope, and love are more robustly associated with life satisfaction than the more cognitive strengths like curiosity or love of learning. This was found to be true among both adults and youths. Longitudinal evidence suggests that these “heart strengths” predict later life satisfaction.



In many ways, the bottom line of positive psychology lies in its ability to increase individual happiness. Therefore, the next section is dedicated to assessing the efficacy of positive psychology interventions.

One note about the word happiness: it’s too broad of a term, and its serious study involves three distinct routes:

  • Positive emotion and pleasure (the pleasant life);
  • Engagement (the engaged life);
  • Meaning (the meaningful life).


Studies show that people vary according to the type of life they pursue, and that the most satisfied people are the ones that pursue all three of the above routes, with the greatest weight on engagement and meaning. We’ll continue to use the word “happiness” to refer jointly to these three paths.

One important factor that has emerged over the years is that “happy people are healthier, more successful and more socially engaged and the causal direction runs both ways” (Seligman, Steen, Park, & Peterson, 2005).

Can Positive Psychology Make People Happier?

Of all the existing positive psychology interventions, which of them really work? And which are, at best, placebos?

One of the methods used to answer questions like these is the random control trial, which randomly assigns people participating in the trial to either the group receiving the treatment under investigation or to a group receiving standard treatment (or placebo treatment), therefore minimizing biases.

Another consideration taken into account is whether or not an intervention has the ability to produce lasting effects on happiness. Research into hedonic adaptation suggests that people rapidly adapt to positive changes and fall back to their baseline levels of happiness.

Seligman, Steen, Park, and Peterson decided to persist and to test the interventions with random control trials.

Validation of the Interventions

Using the internet to recruit and deliver the interventions allowed the authors to collect a sample of 577 adult participants. Out of these, 411 completed all the assessments.

Participants were assessed prior to any intervention on their levels of depression (using the Center for Epidemiological Studies – Depression Scale) as well as happiness (using the Steen Happiness Index). Both of the measuring instruments were chosen for their sensitivity to weekly changes. Participants were followed for six months.

The first large random control trial included five happiness exercises and one placebo control exercise. The happiness exercises included:

  • The gratitude visit, which involved writing and delivering a letter of gratitude;
  • Three good things in life, which involved writing three things that went well each day);
  • You at your best, which involved writing about a time they felt at their best;
  • Using strengths in a new way, in which participants were asked to use their signature strengths in new and different ways every day;
  • Identifying character strengths, in which participants were asked to take the VIA Character Survey in order to identify their strengths.


Meanwhile, the placebo exercise consisted of writing about early memories every night for one week.

Sample Demographics

  • 42% male and 58% female;
  • 64% of participants were between 35 and 54 years old;
  • 39% had a four-year college degree and only 4% didn’t have education or vocational training after high school;
  • 77% were white.


Participants were assessed across the following time points:

  1. Pre-test (before intervention);
  2. Immediate post-test (one week after intervention);
  3. Three months after pre-test;
  4.  Six months after the pre-test.


Two interventions resulted both in an increase in happiness for up to six months and a decrease in depressive symptoms. Those exercises were using signature strengths in a new way and three good things.

The three good things exercise showed beneficial effects one month after the post-test, and these benefits lasted up to 6 months.  A similar long-term effect occurred for the participants with the using strengths in a new way exercise. Immediate effects weren’t as strong as with three good things, but at the one-month follow-up and beyond, participants were happier and less depressed.

The gratitude visit exercise caused the greatest immediate positive change of any of the exercises, but this effect lasted for only one month. Three months after the study, participants were neither happier and nor less depressed than they were at their baseline.

The other two exercises (identifying character strengths and you at your best) and the placebo caused only fleeting positive effects on both happiness and depressive symptoms.

The degree to which participants actively continued their exercises (even though they weren’t specifically instructed to) mediated the long-term benefits. The participants who continued the exercises were the happiest, indicating that the interaction between continuing the exercise and the adherence to the exercise was significant to happiness levels.


The Future of Positive Psychology

Specific interventions make people lastingly happier. Writing about three good things and using character strengths in a new way made people happier and less depressed, even six months later.

Six months might seem to be a long time. However, the findings contradict the notion that any pursuit of happiness is futile because of hedonic adaptation.

As more and more interventions are created, studies will continue to explore which ones work and which are inert. These inert exercises can be used as placebo controls even when they were created as well-being enhancers.

Taking action toward one’s happiness may be sufficient to lift one’s mood in the short term. This would explain the short-term effect experienced in the placebo.

We should take into account that the participants were probably motivated to try things to feel better, and most did, at least in the short term. One week after the study, the placebo group returned to baseline levels of happiness and depressive symptoms and remained there for the following six months.

People in the you at your best cohort showed a similar effect as the placebo group: an immediate boost in happiness and a decrease in depression that didn’t last beyond the post-test, leading to the conclusion that these interventions are not effective, at least not by themselves.

It might be that, if combined in a multi-exercise program that contains inert interventions and effective ones, the benefits exceed those of a single intervention.

These interventions were delivered exclusively online, with no human interaction. It’s often discussed that the power of therapy lies in the client-therapist relationship. Therefore, the benefits of these interventions could potentially be enhanced if delivered through the hands of a skilled clinician or coach.

The sample of this study consisted mainly of well-educated, white, and financially comfortable participants. The participants were also mildly depressed. Further studies on the efficacy of these interventions with individuals who are both much happier and much more depressed, and with people of different socioeconomic statuses, may shed a light on the extent to which these findings can be generalized.

The research also showed a reduction in depressive symptoms, leading to speculation that these interventions may prove therapeutic in depressive states. Positive interventions can be an important supplement to traditional therapy as an additional tool that therapists can use.

Psychotherapy is commonly seen as a place to go to talk about troubles and weaknesses. But, as Seligman, Steen, Park, and Peterson wrote:

“We suggest that the psychotherapy of the future may also be where you go to talk about your strengths” (2005).

A Brief Summary

How would discussing and understanding our strengths shift the struggles and challenges were face? With time, hopefully the field of positive psychology will continue to prove why we need tools reminding us of our strengths, as much as we need tools to cope with our sorrows.

How do you see the field of positive psychology evolving? What changes could benefit the field and strengthen it even more? We would love to hear your thoughts in our comments section below.

Seligman, M. E. P., Steen, T. A., Park, N., & Peterson, C. (2005). Positive psychology progress: Empirical validation of interventions. American Psychologist, 60(5).

About the Author

Catarina Lino's life long passion is well-being. Her quest for meaning led her to Psychology and to pursue an Executive Masters in Positive Psychology which she uses to help people live healthy and full lives. Get to know our whole team!

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