New York, Dec 25 (IANS): Interventions targeted at individual students can improve the classroom environment and trigger a second wave of benefits for all classmates, new research shows.

"Our results suggest that the whole effect of an intervention is more than the sum of its individual effects," said lead author Joseph Powers of Stanford University.

"As a field, we've often focused on understanding and changing individual psychological processes, but these findings show that changing individual psychology can trigger important second-order effects with measurable benefits for everyone in the environment," Powers added.

The findings indicate that sharing a classroom with greater numbers of students who participate in a brief intervention can boost all students' grades over and above the initial benefits of the intervention.

The researchers analyzed data from two previous intervention studies conducted with 7th graders. Both studies were aimed at diminishing the threat of negative stereotypes related to African American students' academic abilities.

The first study took place in 45 classrooms at the beginning of the school year.

On average, about half of the students in each classroom participated in the study and received a writing prompt from their teachers, who were not aware of the research hypothesis.

The prompt instructed some students to write about their most important values, such as friends or artistic ability; these students were in the intervention group.

Other students, assigned to the control group, received a prompt instructing them to write about their least important values.

The data indicated that adding just two African American students to the intervention group in a typical classroom improved the classroom environment enough that low-performing students' grades increased, on average, by a third of a letter grade from a C to a C .

Intriguingly, the boost appeared to be especially strong for low-performing students of all races.

In the second study, a separate group of 7th graders in 15 different classrooms, confirmed these findings.

"It really makes you wonder how often we underestimate the full impact of social interventions," Powers stated.

The intervention may lead to strong indirect effects by strengthening classroom norms of cooperation, order, and growth in ways that benefit all students in the class, the researchers concluded.

The findings were published in the journal Psychological Science.