The repeatability of cognitive performance: a meta-analysis

Abstract

Behavioural and cognitive processes play important roles in mediating an individual's interactions with its environment. Yet, while there is a vast literature on repeatable individual differences in behaviour, relatively little is known about the repeatability of cognitive performance. To further our understanding of the evolution of cognition, we gathered 44 studies on individual performance of 25 species across six animal classes and used meta-analysis to assess whether cognitive performance is repeatable. We compared repeatability (R) in performance (1) on the same task presented at different times (temporal repeatability), and (2) on different tasks that measured the same putative cognitive ability (contextual repeatability). We also addressed whether R estimates were influenced by seven extrinsic factors (moderators): type of cognitive performance measurement, type of cognitive task, delay between tests, origin of the subjects, experimental context, taxonomic class and publication status. We found support for both temporal and contextual repeatability of cognitive performance, with mean R estimates ranging between 0.15 and 0.28. Repeatability estimates were mostly influenced by the type of cognitive performance measures and publication status. Our findings highlight the widespread occurrence of consistent inter-individual variation in cognition across a range of taxa which, like behaviour, may be associated with fitness outcomes.This article is part of the theme issue 'Causes and consequences of individual differences in cognitive abilities'.

Keywords: attention; cognitive repeatability; evolutionary biology of cognition; individual differences; learning; memory.

Figure 1.

Temporal repeatability R (unadjusted) and 95% bootstrapped confidence intervals for each dataset. Y-axis provides information about first author, species name, the type of cognitive task and the type of cognitive performance measurement. Cognitive performance measurement was the quantification of a cognitive process using accuracy such as proportion correct (ACC); the number of trials to reach a learning criterion (TTC); success-or-failure binary outcome (SUC); latency (LAT); normalized performance scores (NOR); the number of correct trials or errors over a fixed number of trials (NBT). The types of cognitive task include: mechanical problem solving (PS); discriminative learning (DL); reversal learning (RL); memory (ME); learning (LE); physical cognition (PC), which includes visual exclusion performance, auditory exclusion performance and object permanence; spatial orientation learning (SOL); spatial recognition (SR); and lexical fluency (LF).

Figure 2.

Contextual repeatability R (unadjusted) and 95% bootstrapped confidence intervals for each dataset. Y-axis presents first author, species name, the type of cognitive task and the type of cognitive performance measurement. Cognitive measurement is used to quantify a cognitive process using accuracy such as proportion correct (ACC); the number of trials to reach a learning criterion (TTC); success-or-failure binary outcome (SUC); latency (LAT); normalized performance scores (NOR); the number of correct trials or errors over a fixed number of trials (NBT). The types of cognitive task include: mechanical problem solving (PS); discriminative learning (DL); reversal learning (RL); inhibition (IN); memory (ME); use of human cue (HC); external attention (EA); internal attention (IA); learning (LE); physical cognition (PC) that includes visual exclusion performance, auditory exclusion performance and object permanence; and spatial orientation learning (SOL).

Figure 3.

Meta-analytic mean estimates of repeatability (R) for temporal and contextual repeatability including unadjusted, adjusted for test order and adjusted for test order plus individual determinants (sex and/or age). We present posterior means and 95% confidence intervals of meta-analyses obtained from linear mixed-effects models. All estimates are back-transformed into repeatability (R).