Unlike high fidelity prototypes which are very detailed and may look very much like the final interface, low fidelity or ``low-fi'' prototypes are a rough rendition of the interface that presents only the main features. Low-fi prototypes are especially useful in early stage interface design to quickly iterate, test and experiment with new designs.
We tested the low-fi prototype to get early feedback on interfaces for portfolio selection and authentication (we did not compare it to text-based authentication at this stage). The low-fi testing also helped us to determine which variations in the Random Art algorithm produces the most memorable and distinguishable images and served as a way to preselect the images that would be used for future testing.