An orderly, integrated set of statements that describes, explains and predicts behavior. A process of gradually augmenting the same types of skills that were there to begin with. A process in which new and different ways of understanding and responding to the world emerge at specific times. [refer to tables 1. 5 & 1. 6 for study] Species have characteristic that are adapted to their environments. Measures of behavior are taken on large numbers of individuals and age related averages are computed to represent typical development. Elaborate surveys on everything imaginable they tested loads of people with the goals of determining what is normal . In the early 1900 s intelligence tests were developed to identify kids with learning disabilities so that they could be placed in special classes. People move through a series of stages in which they confront conflicts between biological drives and social expectations.