In addition to intelligence, people also have a certain mindset about intelligence. For example, people differ in how strongly they belief that intelligence is fixed versus how much you can grow in intelligence. These are called a fixed mindset and growth mindset, respectively, and they have become a popular topic for scientific research as well as in popular media (Dweck, 2006).
The general idea behind growth mindset is that students who believe that their intelligence can be developed (a growth mindset) outperform those who believe their intelligence is fixed (a fixed mindset). Additionally, when students learn through a structured program that they can “grow their brains” and increase their intellectual abilities, they do better (note that brains do not "grow" as such, but this is how it is framed in growth mindset interventions). A meta-analysis summarized a lot of research on this topic and concluded that there is sufficient evidence for these claims (Burnette et al., 2013).
However, a recent study appears to strongly contradict at least one of the core claims of growth mindset theories. Bahník and Vranka (2017) performed a study with nearly 6000 students who were all participating in a scholastic aptitude test; a requirement to apply for university. In addition to the aptitude test (which is very similar to the GRE used in the United States) they also measured the students' mindset orientation. The results showed that there is no relationship between students' mindset and their test scores. Furthermore, the very small (but statistically insignificant) effect was in favor of a fixed mindset, meaning that students with a growth mindset actually performed very slightly worse than the others.
Due to the enormous scope of the study and the representative sample, this finding casts doubts on the reliability and reproducibilty of growth mindset theories. This study is problematic for growth mindset theories, but despite its size it is 'only' a single study. Nevertheless, caution is advised in regards to the scope and veracity of the claims of growth mindset theories.
Burnette, J. L., O'boyle, E. H., VanEpps, E. M., Pollack, J. M., & Finkel, E. J. (2013). Mind-sets matter: A meta-analytic review of implicit theories and self-regulation.
Bahník, Š., & Vranka, M. A. (2017). Growth mindset is not associated with scholastic aptitude in a large sample of university applicants. Personality and Individual Differences, 117, 139-143.
Dweck, C. S. (2006). Mindset: The new psychology of success. Random House Incorporated.