Experience

The six senses of INVEST are sight, smell, hearing, taste, touch, and thought.

Experience is the processing of sensory inputs. 

The main point of this example is to show that there is a process occurring in every marketing campaign, though maybe unnoticed. The stimulation of one sense leads to the initiation of other senses, and this is crucial to converting a consumer into a customer. All successful marketing campaigns rely on this sensory conversion, whether they realize it or not.