The impact of values of affirmation on academic performance is such an effect.
Values-affirmation "undoes" the effect of stereotype threat (also called identity threat). Stereotype threat occurs when a person is concerned about confirming a negative stereotype about his or her group. In other words a boy is so consumed with thinking "Everyone expects me to do poorly on this test because I'm African-American" that his performance actually is compromised (see Walton & Spencer, 2009 for a review).
One way to combat stereotype threat is to give the student better resources to deal with the threat--make the student feel more confident, more able to control the things that matter in his or her life.
That's where values affirmation comes in.
In this procedure, students are provided a list of values (e.g., relationships with family members, being good at art) and are asked to pick three that are most important to them and to write about why they are so important. In the control condition, students pick three values they imagine might be important to someone else.
Randomized control trials show that this brief intervention boosts school grades (e.g., Cohen et al, 2006).
One theory is that values affirmation gives students a greater sense of belonging, of being more connected to other people.
(The importance of social connection is an emerging theme in other research areas. For example, you may have heard about the studies showing that people are less anxious when anticipating a painful electric shock if they are holding the hand of a friend or loved one.)
A new study (Shnabel et al, 2013) directly tested the idea that writing about social belonging might be a vital element in making values affirmation work.
In Experiment 1 they tested 169 Black and 186 White seventh graders in a correlational study. They did the values-affirmation writing exercise, as described above. The dependent measure was change in GPA (pre-intervention vs. post-intervention.) The experimetners found that writing about social belonging in the writing assignment was associated with a greater increase in GPA for Black students (but not for White students, indicating that the effect is due to reduction in stereotype threat.)
In Experiment 2, they used an experimental design, testing 62 male and 55 female college undergraduates on a standardized math test. Some were specifically told to write about social belonging and others were given standard affirmation writing instructions. Female students in the former group outscored those in the latter group. (And there was no effect for male students.)
The brevity of the intervention relative to the apparent duration of the effect still surprise me. But this new study gives some insight into why it works in the first place.
Cohen, G. L., Garcia, J., Apfel, N., & Master, A. (2006). Reducing
the racial achievement gap: A social-psychological interven-tion. Science, 313, 1307-1310.
Shnabel, N., Purdie-Vaughns, V., Cook, J. E., Garcia, J., & Cohen, G. L. (2013). Demystifying values-affirmation interventions: Writing about social belonging is a key to buffering against identity threat. Personality and Social Psychology Bulletin,
Walton, G. M., & Spencer, S. J. (2009). Latent ability: Grades and test
scores systematically underestimate the intellectual ability of negatively stereotyped students. Psychological Science, 20, 1132-1139.