There are three main contributors to impulse buying behavior: 1. Highly stimulating store environments and perceived crowding increases impulse buys, especially for repeat vs. first time shoppers. Large stores influence through displays while small stores use pricing. 2. Certain psychological traits like general impulsivity contribute, but only if the person finds impulse buys morally acceptable. Getting good deals releases mood-boosting endorphins. 3. The longer a shopper spends in a store before finding their intended purchase, the more likely they are to make an unplanned buy. Distracted shoppers are also more susceptible to implicit marketing primes.