Summary.Children between the ages of 11 and 15 marked Raven'sProgressive Matricestwice: first at speed, so that the test resembled one in perceptual organisation; later at leisure, to allow time for thought. It was predicted that more younger children and more educationally backward children would, on the second occasion, change right answers to wrong ones. The suggestion is that, at the lower levels, language‐handicaps affect reasoning‐ability advers