Blue for addition and red for subtraction: the effect of color congruence on arithmetic operations

Purpose This study aims to investigate whether the color blue facilitates better performance in forward calculations (addition and multiplication) and if the color red enhances performance in recessive calculations (subtraction and division). Design/methodology/approach Four experiments were conducted in Korea. Studies 1A and 1B explored whether a blue background enhanced performance in addition and multiplication, while a red background enhanced performance in subtraction and division, and focused on the mechanisms underlying the effect of arithmetic operation and color. Studies 2A and 2B assessed whether the effects of arithmetic operation and color on computational performance remained consistent when numbers were presented alongside units in a purchase context. Findings Results demonstrate that the increment and/or upward concept associated with blue improves performance in tasks related to numerical increments, such as addition and multiplication. In contrast, the decrement and/or downward concept associated with red enhances performance in tasks related to numerical decrements, such as subtraction and division. Practical implications Results can be applied in the digital shopping interfaces to promote better decision-making. Online shopping sites or mobile platforms can incorporate blue backgrounds for adding benefits or cumulative rewards and red backgrounds for emphasizing subtracting quantities. Originality/value The study identifies perceived processing fluency and computational complexity as underlying mechanisms influencing the effects of color congruence on arithmetic performance.