L.L. Thurstone was an American psychologist born in 1887, known for his work in the field of psychometrics and intelligence testing. He developed the Thurstone's primary mental abilities theory, which proposed that intelligence is made up of several distinct factors rather than a single general ability. This approach challenged the prevailing views of intelligence at the time. Thurstone also contributed to the development of the Thurstone scale, a method for measuring attitudes and opinions. His research laid the groundwork for future studies in psychology and education, influencing how intelligence and abilities are assessed in various contexts.