Difficulty like complexity is hard to define as well as it largely depends on the individual’s perspective. One way of judging difficulty is by seeing if the attempts at learning a certain aspect of a language sees a larger number of failures than successes. This example is just one way of measuring difficulty. Difficulty like cost, seen above, and many other terms in the agent related model is extremely subjective and Dahl has not given a concrete definition to these. Thus it appears as these must be define in relation to the individual.

From a more purely linguistic point of view, we could also judge a language as more difficult if its language structure and system differ greatly from any of the languages that a person is native to or proficient in.