Impact of the COVID-19 pandemic on intelligence quotients of students

In a recent study published in PLOS ONE, researchers assessed the impact of irregular schooling during the coronavirus disease 2019 (COVID-19) pandemic on the intelligence quotients (IQs) of students.

Study: Students’ intelligence test results after six and sixteen months of irregular schooling due to the COVID-19 pandemic. Image Credit: Drazen Zigic/ShutterstockStudy: Students’ intelligence test results after six and sixteen months of irregular schooling due to the COVID-19 pandemic. Image Credit: Drazen Zigic/Shutterstock


The COVID-19 pandemic and the related countermeasures have resulted in numerous temporary but extensive effects on global societal systems, including work, social life, education, and culture. Several institutions including schools were unprepared for a major shift and partial closure of their operations, resulting in a protracted period of improvised teaching along with school absenteeism worldwide.

Several potential repercussions of the disturbance in normal schooling have been studied and researched, such as learning loss, students' sentiments, and mental health as well as students' experiences and views toward online learning. However, the impact of the pandemic on students' intelligence is scarcely understood.

About the study

In the present study, researchers assessed the intelligence test scores of grades 7 to 9 secondary school students during the initial phase of the COVID-19 pandemic and student samples assessed in 2002.

Between August and September 2020, 424 pupils in the seventh, eighth, and ninth grades answered the Berlin Structure-of-Intelligence Test (BIS-HB). In four German grammar schools in Rhineland-Palatine, these pupils attended either regular or special classes. The sample cohort had an average age of 13.34 years with 41.98% female students. In July 2021, 257 students with an assessed IQ score at the initial measurement point were retested.

The BIS-HB involves a paper-and-pencil intelligence exam developed to measure the intellectual structure of teenagers with above-average and superior abilities. The operation component consists of processing speed [S], creativity [C],  memory [M], and reasoning [R]. The exam content comprises linguistic, numerical, and figurative skills. Each test item is associated with a certain mix of content and operation. From 2011 to 2013 (called the "2012 sample"), the BIS-HB was administered to 197 eighth-grade children from the same four schools as the students in the 2020 sample. In 2002, 1,506 pupils in grades 5 to 10 from schools in five German states were also assessed as part of the BIS-HB standards.

A comparison of the 2020 sample against the 2002 sample was performed in analysis 1a and a comparison of the 2020 sample to the 2012 sample as well as the 2002 samples was performed in analysis 1b.


In Analysis 1a, the propensity score (PS) matching algorithm paired 104 students belonging to the 2002 sample with 104 students belonging to the 2020 sample. The proportions of class type, grade level, and gender in the matched samples were identical, and there were minimal differences in age and PS. The multivariate analysis of variance (MANOVA) revealed a large and statistically significant variation between the samples' BIS-HB values, with the matched 2002 sample performing significantly better. Analysis of the discriminant function revealed a significant function that distinguished the 2002 sample from the 2020 sample.

All intelligence scales, except for creativity, displayed large structural coefficients showing that the 2002 sample performed significantly better than the 2020 sample. There was essentially no correlation between creativity and the estimated function, hence creativity did not differentiate between the samples. Lastly, the ANOVA discovered a moderate difference in the g-factor between the samples, favoring the matched 2002 sample.

Almost 113 students belonging to the 2012 sample were matched with 113 students belonging to the 2020 sample by PS matching. Using a second PS matching technique, 110 pupils from the 2002 sample were matched with 110 pupils from the 2012 sample. A third PS matching technique then paired 110 pupils belonging to the 2012 sample that was selected by the second PS matching procedure with 11 pupils belonging to the 2020 sample. The examination of discriminant functions revealed two significant functions that distinguished 2002, 2012, and the 2020 samples.

All intelligence scales displayed significant structural coefficients in Function 1. This function differentiated the 2012 sample from the 2002 and the 2020 samples, demonstrating that the 2012 sample had higher IQ scores than the other two samples. On the other hand, function 2 showed that all intelligence scales except C and R exhibited significant structural coefficients. Function 2 mostly distinguished the 2002 sample from the 2020 sample, indicating that the 2002 sample had higher IQ scores.

All scores increased significantly from the tests to retests. The correlations between tests and retests were between r = 0.71 for memory to r = 0.87 for general intelligence. Furthermore, the median improvement in IQ was 6.86 points, varying between 3.56 for creativity and 11.93 for processing speed. For the 2020–2021 school year, there was neither a significant decline in intelligence test scores nor a significant increase that could be regarded as "catching up" to earlier cohorts.


The study findings imply that COVID-19-related issues may affect the cognitive capacities of children. Although intelligence plays a vital role in numerous facets of life, it would be crucial to examine further the disparities between pre-academic and current student samples in order to account for these variations in test norms and for potential disadvantages by delivering appropriate interventions.

Journal reference:
Bhavana Kunkalikar

Written by

Bhavana Kunkalikar

Bhavana Kunkalikar is a medical writer based in Goa, India. Her academic background is in Pharmaceutical sciences and she holds a Bachelor's degree in Pharmacy. Her educational background allowed her to foster an interest in anatomical and physiological sciences. Her college project work based on ‘The manifestations and causes of sickle cell anemia’ formed the stepping stone to a life-long fascination with human pathophysiology.


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