Temporal stability of specific ability scores and intelligence profiles in high ability students

Abstract

Individuals' general intelligence is highly stable over time and strong empirical evidence supports its validity for diagnostic purposes. Frequently, general intelligence is assessed as a composite of different specific cognitive abilities (e.g., verbal, numerical, figural ability). In previous research, these specific abilities only showed marginal stabilities, challenging their validity for diagnostic purposes. However, this research was conducted with samples of predominantly average or low ability individuals. According to Spearman's law of diminishing returns, high ability individuals show more pronounced differences between subtest scores or intelligence profiles than regular ability individuals. Therefore, we aimed to investigate the stabilities of specific abilities and intelligence profiles in high ability individuals. Using the Berlin structure-of-intelligence test (BIS-HB), we investigated the 6-month mean-level change, individual-level change, differential continuity, and ipsative continuity of specific abilities in a sample of 114 students (28.9% female; age M = 14.11, SD = 0.84) attending special gifted classes. We found significant mean-level change for all specific abilities. Reliable individual-level increases in performance were observed for, on average, 15.4% of the participants on each specific ability (based on SEpred). Differential continuity of specific abilities ranged from 0.72 to 0.84. Intelligence profiles replicated across test–retest occasions significantly above chance levels (Mdnκ = 0.32). The results render more precisely the usefulness of interpreting intelligence profiles, which has previously been called into question in general.