Overview
Externally, Betazoids are nearly indistinguishable from humans, the only difference being that the iris of a Betazoid's eyes is somewhat larger than a human's, and completely black (although as yet it is unclear if it is or is not aniridia). The Betazoid brain contains the paracortex, which is a lobe devoted specifically to telepathy. Betazoids are empathic and telepathic (they can communicate telepathically with other Betazoids and some other aliens, and can sense the emotions of a wide variety of species). Betazoid/human hybrids (like Deanna Troi), however, are just empaths, not telepaths (although still able to communicate telepathically with full Betazoids, and with those very close to them i.e. Deanna Troi and her imzadi (first true love), William Riker and also her mother).
While most Betazoids develop their telepathic powers at the onset of adolescence, and they gradually develop after that, a small number are born fully telepathic, although no one knows exactly why. Betazoids born with their telepathic abilities fully developed almost never lead normal lives - they are constantly bombarded with the thoughts of others around them, and drive themselves to distraction attempting to block out the never-ending telepathic "attack". Tam Elbrun suffered from this condition. Though also rare, Betazoids can be born without any telepathic ability, leading to sociopathic behavior. Lon Suder is a Betazoid without telepathic ability.
The REM frequency of sleeping Betazoids is different from that of most humanoids.
Because they can sense the emotions and sometimes thoughts of others, their culture has evolved to be totally honest and nonprivate; for example, their wedding ceremonies are performed in the nude. Betazoids feel uncomfortable around species whose minds they cannot read, including the Ferengi (whose brain is different from most humanoids), Changelings, who don't have a distinct "brain" (i.e.- an organ constituting their mind and mental functions), and the Breen.
Betazoid society includes a complex hereditary nobility (which is not bound to any actual social privilege). For example, Betazoid ambassador Lwaxana Troi was formally titled Daughter of the Fifth House, Holder of the Sacred Chalice of Riix, and Heir to the Holy Rings of Betazed. Members of the nobility are usually betrothed at a very early age.
The gestation period for Betazoids is typically 10 months. At around age 40, Betazoid females enter a period of increased sexual desire called "the phase" . A Betazoid woman's sex drive will typically quadruple (or more) in intensity during the phase.
At one time, it was fashionable for Betazoid women to wear elaborate wigs that encaged small animals. The practice, which was cruel to the animals, was stopped when one woman stood up against it.
The Betazoid word imzadi means "beloved", although in the (non-canon, like all Star Trek books) novel "Imzadi", by Peter David, the meaning is expanded to mean "the first", as in the first to touch one's soul. This explains why Deanna Troi calls William Riker imzadi when they meet in the episode "Encounter at Farpoint", even though they had not been lovers for years.
For most of TNG's run, Troi speaks with a distinctive accent. In the Season 1 cast interviews, it is revealed that the accent was "created" by Marina Sirtis when she was asked to modify an Eastern European accent to make it a distinct Betazoid accent, and she combined it with a Hebrew accent. However, when Majel Barrett was cast to play Troi's mother Lwaxana Troi, since Majel had an American accent, the accent was attributed to come from Troi's father (a human) instead. However, over the years Troi's use of the accent has gradually diminished; also, when Ian Troi finally appeared onscreen (played by Amick Byram in the episode "Dark Page"), he spoke with an American accent.
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