What is Cognitive Friction?
Cognitive friction occurs when the user faces an interface or ability that appears intuitive but produces unexpected results. This mismatch between the result of an action and the expected outcome causes user frustration and will worsen if it does not endanger the user experience.
Cognitive friction is a user experience problem that occurs when an interface does not function as expected and requires too much cognitive load to complete a given task.
For example, when shopping online you add items to your cart or bag, just like you do when shopping in real life.
Imagine if you visited an e-commerce site that prompted you to "save" or "bookmark" an item - you would probably be confused or feel uncomfortable, and leave such a site.
To avoid such issues, UX designers try to make an interface mimic the real world as much as possible, making it more intuitive.