An aptitude is an innate inborn ability to do a certain kind of work. Aptitudes may be physical or mental. Aptitude and intelligence quotient are related, and in some ways opposite, views of human mental ability. Whereas intelligence quotient sees intelligence as being a single measurable characteristic affecting all mental ability, aptitude breaks mental ability down into many different characteristics which are supposed to be more or less independent of each other. However, a casual analysis of any group of test scores will nearly always show them to be highly correlated.