Thea Klapp, Jan-Eric Gustafsson, Stefan Johansson
The big-fish–little-pond effect (BFLPE) is a well-supported contextual effect that hypothesizes that school-average achievement is negatively related to academic self-concept, even though the relation between individual achievement and self-concept tends to be positive. However, there are some uncertainties about possible moderators of the BFLPE. The bright-student hypothesis assumes that the negative relation between school-average achievement and student self-concept is less strong for higher achieving students. This hypothesis has been tested mainly with measures of individual achievement, but there have been few or no attempts to investigate if the BFLPE varies by individual cognitive ability. The objective of the present study was to provide clarity on the issue by using a measure of cognitive ability, operationalized as students’ verbal, spatial, and inductive abilities, to study the moderating effect of cognitive ability across levels. Multilevel structural equation modeling was used to test the BFLPE in the mathematics and language domains using Swedish representative ninth-grade data (N = 24,771). Support for the BFLPE was found in the mathematics domain (b = −0.32, p < .001) and the language domain (b = −0.23, p < .001). A statistically significant cross-level interaction effect was found between individual cognitive ability and school-average achievement in the mathematics domain (b = 0.22, p < .001) but not in the language domain (b = 0.07, p = .051). This indicated that the negative relation between school-average mathematics achievement and mathematics self-concept was less strong for students with higher cognitive abilities, thus supporting the bright-student hypothesis. (PsycInfo Database Record (c) 2025 APA, all rights reserved)