Every interface is a series of decisions. Click or scroll. Read or skip. Buy or bounce. Each micro-decision costs cognitive resources, and those resources are finite.
This isn't opinion. It's well-studied science.
The Research
Sheena Iyengar's classic jam study showed that consumers presented with 24 varieties were 10x less likely to purchase than those shown 6. The finding has been replicated across domains: retirement plans, medical decisions, software onboarding flows.
The mechanism is ego depletion: the same mental resource that powers self-control also powers decision-making. Drain one, and you drain the other.
What This Means for Product Design
Three principles I apply from this research:
- Reduce option count at every decision point — if you're showing more than 5 options, question whether all of them need to be visible
- Sequence decisions by effort — put simple, low-stakes choices first to build momentum
- Provide smart defaults — the best decision is the one the user doesn't have to make
My cognitive science minor at Rutgers gave me a framework for thinking about these patterns. The intersection of how people think and how products should work is where I want to live.
This is the beginning of a series connecting cog sci research to product decisions.