• Behaviorism consolidated as a methodological paradigm privileging observable behavior, laboratory control, and cross-species generalization, displacing introspective methods in both general and social psychology [4], [6], [9], [10], [12], [13].

• A sustained re-framing of instinct moved from fixed innate faculties to analyzable, learned, and context-shaped tendencies, challenging instinct talk in individual and social domains and proposing appetitive/aversive components or acquisition mechanisms [1], [2], [5], [15], [16].

• Learning and performance were modeled through conditioning, habit formation, and interference, using controlled tasks with animals and humans to reveal acquisition, extinction, and competition among response tendencies [4], [7], [17], [20].

• Emotion research integrated physiological indices, conditioned responses, and perceptual judgments, linking bodily states with fear, hunger, and rage while standardizing facial-expression assessment in experimental settings [3], [17], [18], [19].

• Comparative experimental psychology treated animal models as vehicles for discovering general behavioral principles—using invertebrates, rodents, and birds to study motivation, learning, and sexuality under standardized laboratory conditions [4], [12], [13], [16], [20].