Oooh, I love these kinds of studies, where it's shown quite clearly that testing and grade scores are not the be all and end all of education.
This particular study was conducted by a postdoctoral researcher at the University of Poitiers in Poitiers, France.
"The study noted that the students’ improvement on the tests most likely
was temporary, but the results showed that working memory capacity may
be improved simply by boosting students’ confidence and reducing their
fear of failure. “Our research suggests that students will benefit from
education that gives them room to struggle with difficulty,” Autin said.
“Teachers and parents should emphasize children’s progress rather than
focusing solely on grades and test scores. Learning takes time and each
step in the process should be rewarded, especially at early stages when
students most likely will experience failure.”"