This study considered the information presentation method to help the customers make a concept-articulation type of purchase. When customers follow the concept-articulation type of thinking, they only have vague requirements, and try to make a gradual clarification of what they want through the interaction with salesclerks and so forth. We constructed a system called S-Conart (Concept Articulator for Shoppers) to support the concept-articulation type of purchase based on the observations from an analysis of human behavior in actual purchase activities. The user study conducted using S-Conart suggests that changing the contents and/or the method of presenting information can bring an change to the human mental world, which is also observed when sales-clerk appropriately reacts to the customer in a real-life shopping situation, although in a different form. The result of this user study suggests the possibility of a chance discovery by the customers themselves, which is expected to be useful for building the support system for concept-articulation type of shoppers.