Physical prototypes use a range of fidelity, from low fidelity to high fidelity. Low-fidelity prototypes test general ideas quickly, while high-fidelity prototypes closely reproduce the intended product for realistic user and performance testing.
How fidelity changes
Fidelity is the degree of accuracy or realism with which a prototype represents the intended final product. In B2.2 Modelling and prototyping, fidelity can relate to scale, shape, space, aesthetics, materials, function and performance.
| Level | Characteristics and purpose | Example |
|---|---|---|
| Low fidelity | Simplified, inexpensive and quick to construct. It tests general principles such as overall size, form, layout or basic user interaction. It is easy to modify during early iterations. | A full-scale cardboard mock-up of a desk organizer used to test compartment positions. |
| High fidelity | Closely mimics the final product in dimensions, appearance, materials, function or performance. It supports detailed testing against several design specifications and produces more realistic end-user feedback. | A working desk organizer made from the proposed material, with finished surfaces and moving components. |
Fidelity is a continuum, not necessarily a set of rigid categories. A prototype may have high aesthetic fidelity but low functional fidelity. For example, a painted foam model may accurately represent a product's shape and colour while containing no working mechanism.
Designers increase fidelity through repeated model, test, refine cycles. Early low-fidelity models expose major problems without wasting resources; later high-fidelity models allow the selected design to be tested in its intended environment by the intended users.
A common misconception is that higher fidelity is always better. The appropriate level depends on the purpose of the test: using expensive final materials is unnecessary when only size or spatial arrangement is being evaluated.
Exam technique
For an IB response, define fidelity, contrast low and high fidelity, and connect each level to a specific testing purpose. If asked to explain or evaluate, show why fidelity should increase during iteration and mention the trade-off between realistic evidence and the greater time, cost and difficulty of modification.