Goal-Gradient Effect

The behavioral pattern in which motivation, effort, and purchase frequency increase as an agent approaches a goal. Originally documented by Clark Hull (1934) in animal maze experiments, the effect was brought into marketing by Kivetz, Urminsky, and Zheng (2006), who showed that loyalty-card holders accelerate their purchase rate as they approach a reward threshold.

In retail and e-commerce, the effect explains why shoppers near a free-shipping minimum add low-value items to their cart, and why uniform-price section shoppers accelerate spending as their implicit budget nears zero.