A psychological intervention strengthens students' peer social networks and promotes persistence in STEM

Abstract

Retaining students in science, technology, engineering, and math (STEM) fields is critical as demand for STEM graduates increases. Whereas many approaches to improve persistence target individuals' internal beliefs, skills, and traits, the intervention in this experiment strengthened students' peer social networks to help them persevere. Students in a gateway biology course were randomly assigned to complete a control or values affirmation exercise, a psychological intervention hypothesized to have positive social effects. By the end of the term, affirmed students had an estimated 29% more friends in the course on average than controls. Affirmation also prompted structural changes in students' network positions such that affirmed students were more central in the overall course friendship network. These differing social trajectories predicted STEM persistence: Affirmed students were 11.7 percentage points more likely than controls to take the next course in the bioscience sequence, an effect that was statistically mediated by students' end-of-semester friendships.

Fig. 1. Course friendship networks.

(A) Friendship network at the start of the semester (460 students, 855 ties) and (B) friendship network at the end of the semester (394 students, 629 ties).

Fig. 2. Effects of the intervention on students’ friendship network centrality.

There were no significant differences by condition in network centrality at the beginning of the semester (baseline). By the end of the semester (after intervention), however, affirmed students had (A) significantly higher closeness centrality, (B) slightly but not significantly higher betweenness centrality, and (C) significantly higher degree centrality. Points show raw data and means by condition at each time point, and error bars represent ±1 SE of the mean.

Fig. 3. Mediation analysis.

Path diagram with point estimates (posterior means) of effect parameters and associated 95% credible intervals, using Bayesian estimation with default settings in Mplus (uninformative priors and two Markov chain Monte Carlo chains). Reported p_{positive-effect} values indicate the probability that the effect is not greater than 0 so can be interpreted similarly to a one-tailed P value. This model controls for baseline closeness centrality, but results do not differ meaningfully when the baseline covariate is omitted. (A) The total effect of intervention condition on enrollment in the next course was 0.43, SE = 0.18, 95% CI (0.08 to 0.79), P_{positive-effect} = 0.008. (B) There was an indirect effect of intervention condition on enrollment in the next course through closeness centrality at the end of the semester [estimated effect of 0.13, SE = 0.06, 95% CI (0.04 to 0.28), P_{positive-effect} = 0.003], while the 95% credible interval for the direct effect dropped to include 0 [estimated effect of 0.29, SE = 0.18, 95% CI (−0.05 to 0.64), P_{positive-effect} = 0.05]. This suggests that the greater likelihood of affirmed students taking the next biology course was, in part, explained by affirmation-induced increases in closeness centrality in the course friendship network: Closeness centrality at the end of the semester explained 31% of the variance in the effect of intervention condition on enrollment in the next course.