A Teenager\'s intelligence is not fixed as usually thought. Instead, it can go through swings in a few years, according to a British study reported online in Nature. Teenagers\' IQ can rise or fall 20 points over time, researchers from Wellcome Trust Centre for Neuroimaging of Kings College, showed in their study. IQ (short for \"intelligent quotient\") is an gauge of mental capability measured through a series of standardized tests of language skill, spatial ability, arithmetic, memory and reasoning. To get the findings, Cathy Price, senior researcher of the study, and her colleagues tested 33 British teenagers between the ages of 12 to 16 in 2004, who had average IQ scores around 100. Then the teenagers were retested four years later The researchers found the volunteers\' IQ scores went up and down over the four years, with some teenager\'s scores rising by as many as 20 points, and others\' dropping by the same points. \"That is quite astounding,\" cheered psychologist Robert Plomin from the same university but not involved in the study. Dr. Price and her colleagues don\'t know the causes of such fluctuations in the scores they tested, but speculate that learning experiences might account the changes, reported by the Wall Street Journal Today. \"We have to be careful not to write off poorer performers at an early stage when in fact their IQ may improve significantly given a few more years,\" stated Dr. Price cited by the Huffington Post.