Vending Machine Evaluation

To evaluate our new vending machine re-design, we prototyped a life-sized physical model on which to conduct our user testing. We tested the prototype with 3 users and came up with some initial results to help us make improvements on the next design iteration.

User Testing

In general, users liked the coin bucket for dropping change all at once and especially the idea of being able to pay for a drink with a combination of coins and Octopus card. Having a touch-based screen with clear icons made it easier to make selections and updating the screen view based on context made it easier to understand (for example, only showing pictures of the available drinks). Additionally, users enjoyed ease of collecting the drink without needing to bend down to pick it up.

However, our interface and screen flow still didn’t easily support the task of buying multiple drinks or different kinds of drinks in one transaction. Thus, we re-thought our interface as a single dynamic screen to provide clear feedback of user choices and actions through animations. For ease of use, the interface supports variations of actions, whether it be simple selection and/or drag & drop, allows mistake fixes, and provides prompts to help users when no input/action has been received for a while.

Results

Fast prototyping of a physical model allowed us to quickly test and validate our ideas while highlighting problems to solve in the next iteration. In the book The Art of Innovation, one IDEO designer talks about “build[ing] to learn.” And indeed, our prototype helped us shape an improved vending machine concept that was understood by everyone and created an enjoyable user interaction and experience.

{ Tags: concept, prototype, tangible }