Primary and secondary gain
In medicine, the reporting of symptoms by a patient may have significant psychological motivators. Psychologists sometimes categorize these motivators into primary or secondary gain.
Primary gain is internally good; motivationally. For example, a patient might feel guilty about being unable to perform some task. If he has a medical condition justifying his inability, he might not feel so bad. Primary gain can be a component of any disease, but is most dramatically demonstrated in Conversion Disorder (a psychiatric disorder in which stressors manifest themselves as physical symptoms without organic causes - such as a person who becomes blindly inactive after seeing a murder). The "gain" may not be particularly evident to an outside observer.
Secondary gain can also be a component of any disease, but is an external motivator. If a patient's disease allows him/her to miss work, gains him/her sympathy, or avoids a jail sentence, these would be examples of secondary gain. These may, but need not be, recognized by the patient. If he/she is deliberately exaggerating symptoms for personal gain, then he/she is malingering. However, secondary gain may simply be an unconscious psychological component of symptoms and other personalities.
A less well studied process is tertiary gain: the extent to which the patient's symptoms may become more pronounced to subconsciously please health care providers.
Source: DSM-IV-TR