Case study, part 2 of 2

From research to interface

Part 1 covered the problem and the evidence. This part covers what was built from it: the structure, the flow, the screens, the rules that keep the interface consistent, how it will be tested, and how it could earn money. Read part 1 first if you have not.

01 Information architecture

An app that holds your data and an extension that meets you where you shop.

The first IA put a Shop tab inside the app. Part 1 showed why that fails: most regretted purchases start in a feed, not a store the user opens on purpose. The product split into two surfaces that share one backend.

The app Home base. Owns your data. Home Patterns Progress Account, privacy, quiet mode Browser extension Lives where shopping happens. Detect add to cart Overlay check in Works on any Shopify or web checkout Shared backend Insights, score, triggers Merchant dashboard (return rate analytics)
Honest limit: a browser extension cannot reach native in-app purchases inside mobile social apps. v1 covers desktop and mobile web checkout.
02 Core flow

The spending moment, step by step.

Everything the product does converges on one interaction. It triggers when an item is added to the cart, takes about twenty seconds, and every outcome is logged as a win. Dashed steps are optional.

01
Add to cartExtension detects the event and opens the check in.
02
Quiet scanCamera mirror, on device only. Skippable.
03
Three questionsFeeling, planned or not, could it wait 20 minutes. Order varies.
04
Grounding pauseTen seconds, only if the answer was "I need it now".
05
Own wordsOne line on why this, why now. Skippable.
06
InsightOne sentence from Nudge. Never a score, never a verdict.
07
Your callSave for 20 minutes, remove, or buy anyway.
08
LoggedConfidence score rises for every outcome. History updates.
A skip link to checkout is visible on the very first screen. The product never traps the user. A tool that feels inescapable behaves like the pressure it is meant to counter.
03 Wireframes

Low fidelity, built to argue about structure.

These are the revised wireframes. They are deliberately grey: the question at this stage is hierarchy and flow, not polish. The interactive demo shows the same screens at high fidelity.

Clothes and fashion
Tech and gadgets
Food and drinks
Home and living
Continue
Fingerprint question
Let's go
Skip to checkout
Cart check in
Good
Stressed
Tired
Bored
Continue
Question
Save for 20 min
Remove
Buy anyway
Insight and choice
Patterns
04 Design system

Rules that make "no judgement" visible.

Principles

Witness, never judge

No warning colours or verdicts on past purchases.

Every outcome is a win

Buying, pausing, and removing all raise the score.

Quiet by default

Private notifications. Nothing visible to a bystander.

On device first

Anything involving the camera is processed locally.

Colour

Red and amber are banned from the spending experience. They read as danger and would teach the user to associate buying with wrongdoing. They are reserved for system errors such as a failed payment.

Purple 50
Purple 400
Purple 600
Teal 50
Teal 600
Gray 50

Voice

AvoidYou are about to make an impulse purchase.
UseQuick check before this one. How are you feeling?
AvoidYour impulsivity score this week: 75%
UseYou tend to shop when you are tired. Worth knowing.
AvoidAre you sure? This looks like a bad decision.
UseNo wrong answer here. What feels right?

Nudge is the named coach. It asks more than it tells, opens with something specific and observed, and never uses clinical or moralising language.

05 Psychology in the interface

Each mechanic has a reason, and a risk.

MechanicPrincipleRisk to watch
Question order variesFresh prompts resist habituation (Fogg)Harder to build consistent pattern data
10 second pause on "I need it now"Friction scales with urgencyUsers abandon the flow instead of waiting
"Buy anyway" is the quietest optionChoice architecture, defaults steerSteering is still influence. Must be disclosed
Optional line in the user's own wordsCommitment and consistency (Cialdini)May read as friction. Untested
Short delay before the score appearsAnticipation, variable reinforcementBorrows the mechanic it aims to counter
The central tension: the product uses persuasive design to fight persuasive design. The defence is that engagement mechanics aimed at reflection serve the user. The counter is that a person cannot consent to mechanics they are not shown. The response is to name them, as this table does, and to treat user reported discomfort as a stop condition in testing.
06 Testing plan

Most of this is a hypothesis until it is tested.

1

Concept validation, about 15 people

Click through the prototype while thinking aloud, using a product they were genuinely considering. Anything that fails is cut or redesigned.

2

Closed beta, 150 to 300 users

A working build over at least four weeks, with weekly check in surveys and screen level analytics. Retention needs eight to twelve weeks before any decision rests on it.

3

Merchant pilot, 3 to 5 stores

Eight weeks against a held out control period. This is the only stage that can test the return rate claim with real transactions.

4

Staged rollout

10, 25, 50, then 100 percent, with rollback per cohort. The A/B infrastructure stays on permanently.

A/B hypotheses

Question order

Varying order keeps the check from becoming autopilot.

A Fixed order
B Varying order

Metric: completion rate by week four, plus tap speed over time as an autopilot signal.

Reason field

Writing a reason may raise follow through. It may also just add friction.

A No field
B Optional field

Metric: does writing a reason predict waiting out the pause. If over 80 percent skip it, cut it.

Grounding pause

A pause on high urgency should raise pause and remove rates without raising abandonment.

A No pause
B 10 second pause

Metric: outcome mix among "I need it now" users. Watch for abandonment spikes.

Score reveal

A short delay may feel rewarding or manipulative.

A Instant
B Delayed

Metric: next day open rate. In the survey, reported discomfort overrides a positive number.

Success measures (targets, not results)

MeasureTarget
Check in completionover 60% by week 4
Pause then removeover 35%
30 day retentionover 25%
Score trending up70% of active users by week 6
Merchant return ratesignificant drop against control

Known risks: novelty inflating beta engagement, merchants who volunteer already having healthier return rates, and users performing "pause" to watch the score climb. The third is the likeliest and the hardest to see in analytics.

07 Business model

Merchants fund it. Shoppers keep it free.

All figures here are planning assumptions, not measured results. The pilot exists to find out whether they hold.
Launch first

Fashion, beauty, lifestyle

Emotional, identity driven purchases with high regret returns. This is where the mechanism has something to act on.

Deprioritise

Hardware and staples

Functional, pre planned purchases. A pause prompt has little to change.

StreamModel (hypothesis)
ShoppersCore experience free. A premium tier later for deeper trigger analysis and bank connection.
Merchants, installFree
Merchants, analyticsFlat monthly fee, to be tested against willingness to pay
Merchants, performanceSmall share of verified return savings, charged only after a baseline comparison

Monetisation rules

  • No sign up wall before the user has felt value.
  • No countdown timer discounts. A product built to resist urgency cannot sell with it.
  • One paywall screen, never a cascade.
  • Merchant fees tied to proof, so the risk of an unproven claim sits with SpendWise.

Unresolved

  • Native in-app mobile purchases are out of reach for a browser extension.
  • Operating systems or payment platforms could ship a native pause. The merchant relationship and longitudinal data are the defensible parts, which is why the model leans toward B2B.
  • Procurement teams often prefer predictable flat fees over revenue share.
08 Research kit

The instruments for real fieldwork.

These are the questionnaire and interview guide to run with real people. Aim for 20 to 30 survey responses and 5 interviews. Questions ask about a specific recent event instead of general habits, because recall of a real moment is more accurate than self description.

Survey (about 4 minutes)

  1. How old are you?Multiple choice: 18 to 24, 25 to 34, 35 to 44, 45 and over
  2. In the last 30 days, how many online purchases did you later regret or return?0, 1 to 2, 3 to 5, more than 5
  3. Think of your most recent regretted purchase. What were you doing just before?Select all: scrolling social media, stressed, bored, late at night, seeing a friend's purchase, celebrating, other
  4. At that moment, how aware were you that your mood might be affecting the decision?Not at all, slightly, aware but bought anyway, fully aware
  5. What did you do with it afterwards?Kept and used, kept unused, returned, resold
  6. Have you used a budgeting app? If you stopped, why?Never tried, felt judgemental, too much manual work, did not help, still use one
  7. Would a single question before checkout be helpful?Helpful, depends on the question, I would ignore it, annoying
  8. How would you feel about camera based mood detection if all processing stayed on your device?Comfortable, depends on the app, uncomfortable, never
  9. What would make you trust an app like this?Open text
  10. Optional: would you take part in a 20 minute follow up interview?Yes with email, no

Interview guide (20 to 30 minutes)

  1. Tell me about the last thing you bought online that you were not sure about.
  2. Walk me through the hour before you bought it. Where were you, what were you doing?
  3. How were you feeling? When did you first want it?
  4. What happened after the order was placed?
  5. Have you ever tried to stop yourself from buying something? What did you try? Did it work?
  6. Show the prototype. Think aloud as you go through it with a real item you are considering.Observe where they hesitate, skip, or smile. Do not explain.
  7. Which part felt useful? Which part felt annoying or intrusive?
  8. What would make you delete an app like this?
Ethics for a student project: get informed consent, collect no names or payment details, and keep responses anonymous. Be clear to participants that this is a design study and not a financial product.