Gulf of Execution and Evaluation

Donald Norman described the gulf of execution as the degree to which an item corresponds with what a person expects it to do. Said another way, it is the difference between the intention of a user and what the item allows them to do or supports them in doing. A car that has the ability to parallel park itself would have a gulf of execution if the driver expected to push a button labeled “park” and have the car park itself, and the car did not park itself.

The gulf of evaluation is the degree to which an item supports the user in discovering how to interpret the item and interact with it effectively. The same parking example would show a gulf of evaluation if the controls were not designed in such a way that the driver could easily determine how to initiate the self-parking function.