The contrast effect is a cognitive bias where the perception or judgment of a stimulus is influenced by the presence of other, contrasting stimuli, often leading to an exaggeration of perceived differences. This pervasive phenomenon impacts various domains, influencing how experiences are interpreted and decisions are made.Key learnings from the sources include:• Sensory and Physiological: In newborns, a negative contrast effect meant sucking for water decreased after prior exposure to sweeter sucrose, indicating prior reinforcement's influence. Subjective drug effects were perceived as less potent when placebo/no-drug conditions followed strong drugs. Visually, a shape-contrast effect distorts perceived shapes to be more dissimilar to preceding primes, indicating higher-level neural processing.• Social and Cognitive: The effect causes individuals to exaggerate opposing attitudes, exacerbating intergroup conflict. In employment interviews, applicant evaluations are biased by prior candidates. Perceived criminal offence severity is modulated by previous cases, with more severe prior crimes leading to lighter penalties for subsequent ones. In consumer choice, the Background Contrast Effect emerges more under thoughtful conditions, as perceived applicability of prior trade-off values influences current decisions.• Behavioural and Economic: Frequent testing for grades led to lower attendance at optional class meetings. Marketers leverage this effect through pricing and product bundling to influence perceived value and drive sales