In psychology, effortfulness is the subjective experience of exertion when performing an activity, especially the mental concentration and energy required. In many applications, effortfulness is simply reported by a patient, client, or experimental subject. There has been some work establishing an association among reported effortfulness and objective measures, such as in brain imaging. Effortfulness is used as a diagnostic indicator in medical and psychological diagnosis and assessment. It is also used as an indicator in psychological experimentation, especially in the field of memory.