HAI Cambridge Module 1 - Some Notes
Notes from class Human–Computer Interaction (HCI) for AI Systems Design by Prof Ola Kristennson - Cambridge University
Human–AI Interaction Module: Actionable Blog Entries
A ready-to-adapt blog series summarizing the foundations of designing human–AI systems.
Entry 1: Stop Treating HAI Like “Just Another UI”—It Has Its Own Rules
The core idea: Human–AI interaction is not human–computer interaction, and it is not AI engineering. It is its own cross-disciplinary problem that spans HCI, design, engineering design, human factors, and AI. As soon as you infuse AI into an interactive system, you introduce a complex “black box” with its own behavior.
What changes when you add AI:
- Control: AI is a dynamic system. Users struggle to link their actions to outcomes. Actionable tip: map every AI feature to a user-controllable input (e.g., pressure-sensitive typing to indicate certainty).
- Interpretation: AI hides its process. Users see input and output, but not the reasoning. Actionable tip: require an explainability layer for any recommendation your system makes.
- Agency: More automation = less ownership. Users may stop feeling responsible for outcomes (“complacency risk”). Actionable tip: vary the physical or digital surface of interaction to restore agency.
- Governance: Privacy, accountability, safety, security, transparency, fairness, human control, and professional responsibility all become first-class constraints.
Quick checklist before your next sprint:
- Can the user meaningfully control the AI output?
- Can the user interpret why the AI behaved that way?
- Will the user feel like the author of the outcome?
- Have we documented governance risks?
Entry 2: The Six Reasons You Can’t Skip Design
The core idea: Design is not a luxury phase; it is a survival mechanism. Avoiding it has measurable costs.
The six imperatives:
- It is humane: Better interfaces reduce harm. Even mundane AI (like spell check) quietly improves quality of life.
- Computers are hard to use: Office productivity gains are non-trivial. Support systems can fail if they interrupt without benefit (e.g., Clippy).
- Include everyone: Regulation and empathy demand accessibility. Consider adaptive interfaces that personalize themselves to the user over time.
- It is worth it: Poor usability kills morale, productivity, and money. One call-center GUI redesign predicted—and produced—a dramatic productivity drop.
- Invent the future: Capabilities we take for granted (mobile video, speech recognition) existed only because someone designed successive iterations of the future.
- You must, or you will be outcompeted: Product life cycles move through introduction, growth, maturity, and decline. Firms need portfolios of new cycles to survive.
Actionable exercise: Score your current product on a1–5 scale for each of the six imperatives. Any score below 3 is a proposal risk.
Entry 3: Fix the Problem Before You Fall in Love with the Solution
The core idea: Teams often “solve the wrong problem”—they build the thing right, but it is the wrong thing. This is the verification-validation trap: requirements are met, yet the system is unfit for purpose.
What causes it:
- Design fixation: the brief already names the solution (e.g., “use random forests”).
- Too little abstraction: the team never explored a wider design space.
Actionable method—Solution-neutral problem abstraction: Take your current brief and rewrite it at successive levels of abstraction.
| Level | Example |
|---|---|
| Level 1 (Specific) | Automate literature review using LLMs. |
| Level 2 (Streamlined) | Streamline research and publication using AI. |
| Level 3 (General) | Facilitate rapid access and analysis of scientific information through advanced computing. |
| Level 4 (Broad) | Enhance efficiency and effectiveness of information discovery, interpretation, and application in science. |
Do this now: Remove all solution keywords (technology names, interface types) from your problem statement. If the statement still makes sense, you have a properly abstracted problem.
Warning signs you are solving the wrong problem:
- You are copying a metaphor literally (e.g., Microsoft Bob’s “home desktop”).
- You are compromising between two paradigms and pleasing neither (e.g., Sega Saturn’s split focus on 2D and 3D).
Entry 4: Make Your Requirements Specification a Living Contract
The core idea: Requirements are not a one-time document; they are a communication tool, a change-management aid, and a verification backbone.
The four requirement types:
- User-elicited: Effectiveness, efficiency, safety.
- Technical: Size, power, latency, precision/recall.
- Business: Cost, time, IP, resources.
- Regulatory: Legislation, ethics, standards.
Non-negotiable qualities for every requirement:
- Solution independent: Do not prescribe “how,” only “what.”
- Complete: Cover installation, support, maintenance, decommissioning.
- Clear: Unambiguous to any team member.
- Concise: No fluff.
- Testable: Must link to a verification procedure and criteria.
- Traceable: Record the source so you can run traceability analysis when one requirement changes.
Actionable template for your next requirement:
REQ-ID: 001
Source: User interview, June 2026
Statement: The supervisor shall receive a replacement-machine suggestion within 10 seconds of a failure alert.
Test criteria: Simulated failure test; 95% of alerts delivered in <10s under normal load.
Dependencies: REQ-004 (failure-detection latency), REQ-012 (worker-skill database accuracy).
Entry 5: Log Your Trade-offs Explicitly—Because Implicit Ones Kill
The core idea: Every design is an operating point in a multidimensional space. Dimensions conflict. If you do not make trade-offs explicitly, they become implicit design decisions that can lead to unexpected, sometimes fatal, failures.
Example of implicit trade-offs: A patient-controlled analgesia pump cleared inputs after a timeout without making that reset obvious. The result: incorrect doses and patient deaths.
Actionable workshop—The Trade-off Log: Create a table with at least these columns:
| Design Dimension | Option A | Option B | Explicit Decision | Risk if Ignored |
|---|---|---|---|---|
| Battery life vs. Wearable size | 48h / 12mm thick | 24h / 8mm thick | Selected 24h / 8mm for user comfort. | If ignored, users may abandon device due to bulk. |
Rule: If you cannot articulate the trade-off in one sentence, it is still implicit.
Entry 6: Build Personas from a Sampling Frame, Not from Gut Feel
The core idea: You cannot elicit the right requirements if you misunderstand who the user is. Target audience definition prevents sampling frame error and sampling error.
The three sampling criteria:
- Behavioural: Desire or need to interact with the system.
- Technological: Prior familiarity with relevant tech.
- Demographical: Age, income, education, location.
Bias check:
- Detected bias: You know your sample is unrepresentative; you can adjust for it.
- Undetected bias: You do not know it exists. It poisons the design process, leading to systems that pass tests but fail in the real world.
Actionable steps:
- Write an initial profile using all three criteria.
- Refine it by asking: “Which segments provide the most informative feedback?”
- Remove factors unlikely to affect usage.
- Convert the refined profile into 2–3 personas—fictional characters that let the team ask, “Would this decision help or harm Maya?”
Entry 7: Choose the Right User Research Method for the Information You Need
The core idea: Different methods produce different data at different costs. Match the method to the design risk, not just the budget.
| Method | Best for | Key risk / cost |
|---|---|---|
| Non-directed interviews | Deep qualitative insight into reasons, values, and motivations. | Expensive; requires expertise to avoid leading questions and interviewer bias. |
| Focus groups | Prioritizing features, competitive analysis, early idea generation. | Findings do not generalize; people are poor at predicting future behavior. |
| Field visits | Observing actual workflows and tasks in context. | Time-consuming; results are scoped to the observed environment. |
| Diary studies | Tracking infrequent events and daily frustrations over time. | Relies on participant diligence; participants may forget or under-report. |
| Experience Sampling Method (ESM) | Capturing in-the-moment behavior with minimal recall bias. | Data captured per sample is shallow; not suitable for deep exploration. |
| Surveys | Statistical generalization, profiling, satisfaction, value assessment. | Easy to mislead with bad questions; hard to verify respondent honesty or expertise. |
Actionable decision tree:
- Need deep “why”? → Non-directed interviews.
- Need to prioritize features? → Focus groups + follow-up validation.
- Need real workflow truth? → Field visits.
- Need longitudinal habits? → Diary studies or ESM.
- Need numbers to justify a change? → Surveys (but validate with another method).
Entry 8: Sometimes the UI Isn’t Broken—the Task Clarification Is
The core idea: Before redesigning an interface, ask whether the right AI is being applied to the right task. In human–AI interaction, the solution is not always to redraw the UI.
Case study: Smartwatch keyboards. Early proposals redesigned the keyboard entirely (zoomable keys, chording, special gestures). Instead, researchers made the keyboard tiny and let a statistical decoder correct the input. Users typed “as usual.” The breakthrough was not a new UI; it was better task clarification and better AI.
Actionable framework—Task clarification first:
- What is the joint human–computer system supposed to do?
- What is the user’s goal, and what is the machine’s goal?
- Can the user achieve the goal with minimal interface redesign if the AI is improved?
- Only after answering (1)–(3) should you specify UI requirements.
Takeaway: Redesign the intelligence before you redesign the interface.
Use & Remix Guide
- Length: Each entry is designed to stand alone or be merged into a long-form guide.
- Tone: Professional but direct; retains academic rigor while being scannable.
- Next step: Pick the entry that matches your current design phase and run the attached exercise with your team.