The relation between intelligence and reaction time in tasks with increasing cognitive load among athletes with intellectual impairment

Intelligence has long been associated with chronometric performance measures, such as reaction time (RT); however, few studies have investigated this relation in humans at the lower end of the intelligence range. The purpose of this study is to examine the inter-relation between RT, and intelligence in the population of athletes with mild to moderate (IQ 40–75) intellectual impairment (II), according to the DSM-5 diagnostic criteria. IQ-scores were retrieved from the athlete-database, assessed prior to the study by means of the most recently standardized versions of the Stanford-Binet, Raven Progressive Matrices or Wechsler Intelligence Scales, i.e., WISC-V or WAIS-IV. Three RT tasks with increasing cognitive load were administered in this study. The sample consisted of 103 young individuals (32% females, mean age=24.4years, SD=5.8) with II (mean IQ=60.6, SD=9.2), performing the tests prior to competing in the Global Games; the highest level of sport competition, organized by the International Federation for Intellectual Disability Sport. We tested whether IQ and RT were correlated in this sample by means of Pearson's correlations. Afterwards, a comparison sample of tertiary education students was recruited (n=103; mean age=21.1, SD=2.4), whereby for each individual participant with II, a peer was selected on the basis of equal gender, practicing the same sport, and equal accumulated sport expertise. We focused on the possibility that RT tasks requiring higher cognitive load differentiate more between the samples. The 2×3 ANOVA demonstrated a significant group (athletes with II versus comparison group) by task (simple RT, choice RT, complex RT) interaction effect, indicating that the progression of RTs increase across the three tasks with increasing complexity, was more pronounced in the athletes with II than in the comparison sample. This is the first study investigating RT in a large sample of well-trained active individuals with II. It provides a benchmark for other studies and suggests that the impact of lower levels of intelligence on RT is most apparent in RT tasks with the highest cognitive load.