Many studies have documented ‘learning loss’ under lockdown – that is, declines in educational attainment as measured by school examinations. But what about intelligence itself – did that decline too? Yes it may well have done, according to a new German study.
Intelligence is measured through tests of memory, processing speed and abstract reasoning. We know from previous research that education tends to improve people’s intelligence test scores – which isn’t particularly surprising. So it stands to reason that such test scores would fall during a period of sustained learning loss, as occurred under lockdown.
To see whether this was indeed the case, Moritz Breit and colleagues gave an intelligence test to a sample of German children in August/September of 2020 – following several months of remote or hybrid learning. They then compared the children’s scores to those of two earlier samples that were tested in 2002 and 2012. They also retested the original sample ten months later in July of 2021.
A diagram of the school year, indicating when the tests took place, is shown below.
The comparison samples from 2002 and 2012 were taken from the same four schools, and were matched to the original sample using propensity score matching – a technique that ensures you’re comparing apples-to-apples.
Breit and colleagues found that the children tested during the pandemic scored significantly lower than those in the comparison samples – by 7.6 and 5.4 IQ points, respectively. They describe these differences as “remarkably large”.
However, when they retested the original sample ten months later, they found that the average score had increased by 7.5 points. Increased – what’s going on? Was the first result just a fluke? No, not according to the researchers.
Since the participants were 13 years old when the first test was given, their cognitive faculties were still developing (adult intelligence is not usually reached until around age 20). Hence you expect them to do better on the second test – due to general cognitive development.
As Breit and colleagues note, a previous study on German children of similar age, using the same intelligence test, found that the average score increased by 8.8 points over a six-month interval. They therefore interpret the increase they observed as indicating “neither a remarkable decrease nor a “catching up” to previous cohorts”.
The study is not without its limitations. For example, some participants left the sample between the first and second intelligence tests, potentially skewing the results. And the first test took place shortly after the summer break, which may have contributed to the low average score.
Nonetheless, it offers preliminarily evidence that lockdown not only hampered children’s education, but also lowered their intelligence – at least for a time.