The Swiss Cheese Model helps explain why accidents happen, often despite all our best intentions. It occurs when multiple small flaws line up perfectly to create a large failure. What appears to be a sudden disaster is usually the result of many small imperfections quietly lining up.
The Cobra Effect describes situations where the metric improves but the experience does not. Nascent product teams often craft incentives with the noblest of intentions: faster growth, happier users, quarterly bonuses; yet sometimes the universe responds not with improvement but with a sharp increase in the very problem they hoped to solve.
Hick’s Law describes how the time it takes a user to decide increases with the number (and complexity) of choices presented. In UX, it’s a reminder that cluttered interfaces and excessive options slow users down and create cognitive overload.
Recency bias is the tendency for people to weigh the most recent information or experience more heavily than earlier ones, sometimes even disproportionately. In UX, it means users’ judgments and memories of your product are often dominated by what happened last, not by the full journey.
Primacy bias describes how people tend to remember and be influenced more by the first items in a sequence than by those that come later. In UX, it shows up when users disproportionately notice, choose, or recall the first option presented to them, sometimes regardless of whether it’s the best.
Anchoring bias happens when people rely too heavily on the first piece of information they see, the “anchor”, when making decisions. In UX, it shows up when users’ perceptions, expectations, or actions are influenced by an initial number, label, or example, even if it’s arbitrary or irrelevant.
Confirmation bias is the tendency to favor information that confirms what we already believe, while ignoring or discounting evidence that challenges our assumptions. In UX, it shows up when teams interpret user feedback, analytics, or test results through the lens of their preconceived ideas, leading to poor decisions and missed opportunities.
Sunk cost fallacy is the tendency to keep investing time, effort, or money into something, just because you’ve already invested so much, even when it’s clear it’s not working. In UX, this shows up when teams cling to flawed designs, failed features, or outdated systems simply because they don’t want to “waste” what’s already been spent.
Broken Windows UX happens when small, visible flaws in an interface, like typos, misaligned elements, or inconsistent colors, create a perception that the entire product is neglected or unreliable. Even if the core functionality works, those little cracks erode user trust and make the product feel less cared for.
HiPPO stands for Highest Paid Person’s Opinion. It describes the all-too-common situation where decisions about design, product, or strategy are driven not by evidence or user needs, but by the gut feelings of the most senior (and often least informed) person in the room.