Glossary of Technical Terms 827
personality trait domains In the dimensional taxonomy of Section III “Alternative DSM-
5 Model for Personality Disorders,” personalit y traits are organized into five broad do-
mains: N EGATIVE  AFFECTIVITY , DETACHMENT , ANTAGONISM , DISINHIBITION , and P SY-
CHOTICISM . Within these five broad trait domains are 25 specific personality trait facets
(e.g., IMPULSIVITY , RIGID  PERFECTIONISM ).
phobia A persistent fear of a specific object, ac tivity, or situation (i.e., the phobic stimu-
lus) out of proportion to the actual danger posed by the specific object or situation that
results in a compelling desire to avoid it. If  it cannot be avoided, the phobic stimulus is
endured with marked distress.
pica Persistent eating of nonnutritive nonfood substances over a period of at least 1 month.
The eating of nonnutritive nonfood substances is inapprop riate to the developmental
level of the individual (a minimum age of 2 years is suggested fo r diagnosis). The eat-
ing behavior is not part of a culturally supported or socially  normative practice.
polysomnography Polysomnography (PSG), also known as a sleep study, is a multipa-
rametric test used in the study of sleep and as a diagnostic tool in sleep medicine. The
test result is called a polysomnogram,  also abbreviated PSG. PSG monitors many body
functions, including brain (electroencepha lography), eye movements (electro-oculog-
raphy), muscle activity or skeletal muscle  activation (electromyography), and heart
rhythm (electrocardiography).