Illusive Design Pattern

Hidden Costs

The total at the top is different than the total at the bottom as extra fees have been added unexpectedly.


Making prices appear cheaper for transaction completion.


Companies like Airbnb,, Alamo and Aer Lingus excludes taxes and other fees until the last step of the purchasing process. Users spend a lot of cognitive load on analyzing the best deal with budget in mind and they don’t want to lose their investment even with the increased stress of a price change.

Post-AI Altruheuristics

  • Loss Aversion
  • Stress: Lots of time was invested to find the best deal and the user in put in a state of uncertainty.
  • Flow: Price changes at the last step.
  • Trust: Sudden changes, especially in relation to money is illusive as information is being withheld.
CBT Distortions
  • Jumping to Conclusions e.g. Did I do something wrong? Why didn’t I see this before?
  • Personalization e.g. Feel guilty for not seeing this.
  • Blaming - Wasted my time my fault now I have to do it again.
Circ's Principles
  • Calmness: Provide all information required upfront before the journey.
  • Transparency: Reduce anxiety by removing uncertainty and explaining algorithm updates.
Mental Health
  • Chronic Anxiety: Avoid the state of uncertainty and provide reassurance.

Pre-AI Heuristics

Dark Patterns
  • Hidden Costs: After investing time and effort, the user discovers unexpected fees and charges when they reach the checkout.
  • Continuation: The pricing change is a surprise as it’s always larger with the additional fees and the user expects the price to remain exact.
Graphic Design


Don Norman Principles
  • Visibility: The price text is usually small making it less prominent.
  • Feedback: No feedback about the price change is given before or after.
Jakob Nielson Principles
  • Visibility: The price text is usually small making it less prominent.
  • User Control: There is no control over the price change.
  • Match Real World: Asking for money at the end and not upfront breaks real world interaction as it’s considered illusive.