K. warner schaie developed the first study of adult intelligence.

K. warner Schaie developed the first longitudinal study of adult intelligence.

He is a psychologist and a gerontologist who developed the Seattle longitudinal study (SLS) in 1956. The study focuses on understanding cognition and ageing and it was conducted by testing the mental and physical abilities of the subject study.

Some of the findings from his study are listed below:

answer; they both highlight the power of the situation in determining behavior;