The drop in scores marks the end of a trend called the Flynn effect. For the past 60 to 70 years, the average IQ has increased by about 3 percentage points every 10 years.
According to The Times, the scientists called this result 'worry', probably because people spend more time on technology equipment than reading books.
Stuart Ritchie, a psychologist at the University of Edinburgh, was not involved in the study. He told the paper: 'This is by far the most convincing evidence that the Flynn effect is being reversed.'
According to previous research, since the turn of the century, the human IQ index may have declined. Two studies in the UK showed that the index fell by 2.5% to 4.3% every decade. However, this result has not been widely accepted.
A recent study by Ole Rogeburg and Bernt Bratsberg of the Ragnar Frisch Centre for Economic Research in Oslo found that Norwegian men have lower IQ than their fathers.
However, scientists have revealed that often eating fish can not only improve the child's intelligence, but also help them sleep better.
They found that children aged 9 to 11 who had eaten at least once a week were nearly 5 points higher in the IQ test than those who seldom eat it.
