A Misunderstanding is a user mistake where the user did not misunderstand the consequences of an action such that they caused an effect they did not intend. A misunderstanding is distinct from a Miscommunication in that a miscommunication requires that a user did not intend to perform the interaction at all, either because that accidentally triggered an element or mistyped some text. A misunderstanding is best resolved by having good Feedback and by making the interaction Reversible.
The need for feedback and reversibility is the same for misunderstandings and miscommunication, collectively referred to as User Mistakes. The form of feedback required, however, is different. Unlike miscommunications, misunderstandings require that the feedback properly convey the consequences of the action back to the user, rather than just what action was performed. How precise this feedback needs to be depends on the nature of the misunderstanding. Whatever aspect of the consequences the user did not intend is the aspect that needs to be conveyed, and so it changes depending on the user’s intention.
If the full consequences of a user action can be captured on the current screen, they should be. If, however, the consequences are too far-reaching to be represented immediately by feedback, then the application should convey whatever information is most obviously incompatible with mistaken user intentions. If, for instance, a user performs a search and replace on every file in a folder, you cannot tell the user about every replaced string of text in every file, but if the user only intended to replace the text in the current file, stating how many entries changed in how many different files will be enough for the user to catch the issue.
The importance of feedback also depends on the nature of reversibility. If a user action is only reversible by reversing a stack of prior actions, as with an undo button, then the effect of that action must be immediately apparent, and the feedback must be more thorough. If, however, the action can always be reversed no matter how many interim actions have occurred, as in the case of State Change as Filter, then the feedback need not be immediate. The need for immediate, thorough feedback is then dependent on when the reversibility becomes costly or impossible.