Interaction design, user-centred design and the Double Diamond

Interaction design is a process, not a deliverable

Intuition

You cannot guess what a stranger needs from an expense app. You find out, sketch something, watch them use it, and fix what breaks. Interaction design is that loop, written down as a method.

Lecture 3 gives two definitions. Preece (2019): designing interactive products to support the way people communicate and interact in their everyday and working lives. Saffer (2010): the art of facilitating interactions between humans through products and services. It is a goal-directed, creative, problem-solving activity informed by intended use, target domain, materials, cost and feasibility. It is a process focused on discovering requirements, designing to fulfil them, producing prototypes and evaluating them, focused on users and their goals, and it involves trade-offs to balance conflicting requirements. IDEO’s approach (understand, observe, visualise) and the UK Design Council are named as other ways of designing.

User-centred design rests on three principles and on user involvement

John Gould and Clayton Lewis (1985) give the key principles of user-centred design (UCD).

Mechanism

1. Early focus on users and tasks: who is the user, how do they do normal tasks, get the user involved in design.
2. Empirical measurement: the reactions and performance of intended users are observed and measured, for example with simulations and prototypes.
3. Iterative design: when problems are found in testing, fix them and do more tests.

Why involve users? It is the best way to ensure the product is usable and will be used, it creates a sense of ownership, and it supports expectation management. If users feel cheated by promises that were not fulfilled, they resist and reject the product. The lecture cites several studies, and not all point the same way.

Compare

Positive findings

• User involvement raises satisfaction and system use (Abelein et al., 2013).
• For new products, developer satisfaction rose as user satisfaction rose (Subrayaman et al., 2010).
• Involving users earlier led to more creative ideas, later led to service improvement in transport design (Richard et al., 2014).

Cautions

• User satisfaction was higher when participation was low, lower when it was high (Subrayaman et al., 2010).
• High participation can generate conflicts and increase reworking.

Exam detail

Sample exam questions 15 and 16 test UCD. Empirical measurement means design decisions rest on user performance data, feedback comes from simulations and prototypes, and user reactions validate assumptions. It does not mean relying on the designers’ mental models and it is not limited to after launch. Iteration means prototype, refine with real feedback, use qualitative and quantitative feedback, and prioritise high-impact issues. Testing only the final product contradicts iteration.

Pitfall

Sample question 16 includes “make design changes based on cognitive walkthrough” as a wrong option, and the sample’s stated key is the exam-prep answer, so treat that option as wrong there. The lecture grounds iteration in fixing and retesting with real users, but inspections such as walkthroughs can also inform revisions (Lecture 7 folds them into evaluation). Look for “real user”, “prototype” and “feedback” in correct options.

The Double Diamond turns the basic activities into four phases

The lecture links four basic activities of interaction design (discovering requirements, designing alternatives, prototyping, evaluating) to the Double Diamond.

Phase	What happens
Discover	Designers try to gather insights about the problem
Define	Designers develop a clear brief that frames the design challenge
Develop	Solutions or concepts are created, prototyped, tested and iterated
Deliver	The resulting project is finalised, produced and launched

The in-class activity asked pairs to design an expense-tracking mobile app using the first three phases, producing a sketch or two of the main functionality and look and feel. The reflection asked what you did first and which artefacts or experiences your design drew on.

Optional aside

The lecture diagram of the process (a UX design.cc figure) did not extract, so the diverge and converge shape is described from the standard model, not read from the slide. The four phase descriptions above are the slide text.

Recall

Name Gould and Lewis three principles and the Double Diamond phase where a clear problem statement is written.

Early focus on users and tasks, empirical measurement, iterative design. The problem statement is written in Define.