Subjective science: Kenneth Spence's human learning research program.

This article examines Kenneth Spence's human learning research from 1949 to 1967. His works show the conditioning field to be in turmoil over basic issues during this time. These issues included whether determinism should be accepted, how to interpret a psychological test score, what psychometric properties a test should have, and how to use theoretical constructs. Turmoil occurred because behaviors and events had different meanings and degrees of importance to different investigators. Thus, what appeared as "objective" scientific change in the conditioning field was really the adaptation of personal preferences in word meanings, research goals, and research methods. These issues also indicate disputes about definitions and purposes of scientific activity during Spence's era.