Zigler's hypothesis that mental age (MA) and not IQ determines the rate of learning is examined in the light of empirical evidence comparing the learning rates of normal and retarded children and young adults matched for MA. The results show that learning rate is a function of IQ as well as of MA. In general, children of average IQ learned serial and paired-associate lists significantly faster ...

purpose of study : the present research was carried out to study the prevalence of mental retardation among the youth and children of savojbolagh region, and to study its probable causes. method: the study comprised two phases. in the first phase, 1229 girls and boys, aged 5 to 18, were selected from among the children and youth of the urban and rural areas of savojbolagh, through cluster sampl...