Subaddivity Effect

The subaddivity effect is the tendency to judge a project negatively based on looking at the project as a whole rather than as a combination of its parts.

For instance, think of cleaning a dirty house and each room has to be cleaned separately for the task to be complete. Would it be fair for someone else to come in and look at one unfinished room and judging the whole project by that one room? By judging the entire unfinished cleaning job by only viewing one cleaned room would be an example of the subaddivity effect.