Betazoid The Betazoids were a telepathic humanoid civilization originating from the Federation planet Betazed . Physiology . Externally , Betazoids were physically indistinguishable from Human s in every aspect but one : the irises of their eye s were completely black . They could cross - breed with Humans , along with other humanoid races like Klingon s and Tavnian s . Betazoid iris coloration was present in half - Betazoid individuals such as Deanna Troi , but in those with less Betazoid blood such as Devinoni Ral and Walter Pierce ( who were only ¼ Betazoid ) , normal Human eye coloration was possible . ( ) Betazoids had a gestation period of ten months . ( ) Betazoids reached rapid eye movement ( REM ) sleep at a different frequency from other humanoids . ( ) In mid - life , Betazoid females underwent a physiological change known as " The Phase " during which their sex drive increased by a factor of four or more . ( ) Mature Betazoids could also suffer from Zanthi fever , which caused them to lose control over the projective aspect of their empathy . That could result in people around them acting as if they had experienced the same general emotional state as the affected Betazoid , though they were directed by their own subconscious desires , fears , and other emotions . ( ) Telepathic abilities . Betazoids were natural telepaths , an ability centered in their paracortex , with psilosynine being a main neurotransmitter . ( ) Most developed their telepathic skill in adolescence , but a few were born with their telepathic abilities already active , such as Tam Elbrun . ( ) These individuals were almost always extremely talented and powerful in telepathic terms , but also unable to screen out the noise of other people ' s minds , so they generally suffered mental problems of varying severity depending mostly on when the problem was diagnosed . On the other end of the scale were a few individuals who developed psionic abilities which were far below average for the species ( for example , Lon Suder ) . Those Betazoids were barely able to sense even strong emotions ( empath s ) of other people , much less thoughts . The common psionic abilities of Betazoids extended from sensing thoughts and / or emotions , over projecting thoughts and / or emotions , to manipulating the minds of others . ( ; ) How capable they were in performing any of those feats depended somewhat on their genetically - defined psionic strength , their psionic training , ( ) their familiarity with the scanned being , their general mental and physical condition , and the species of the subject race . Betazoids also felt the emotions of animals , and thus were wary of getting too involved in the " passion of the beast " in situations in which they had to rely on an animal , like when riding a horse . ( ) Betazoids also were able to read the emotions and thoughts of non - corporeal beings such as Nagilum , the energy vortex , or to gauge the mental prowess of beings such as Q . Other times they were totally unable to read corporeal creature ' s minds , such as Ferengi and Changeling s . Data theorized that the reason they may not have been able to read Ferengi was the structure of their brains . Data himself was able to be read by Deanna Troi when his brother Lore used the emotion chip to transfer powerful emotions to him . At one point , when Troi lost her empathy temporarily she commented that Will Riker was like a holodeck character to her , completely devoid of emotion , as if she had never experienced a lack of empathy from any sentient before . The Traveler was also not able to be read by Troi . Inter - species reproduction involving Betazoids often affected the psionic abilities of the offspring – most commonly the children of such a union developed empathic abilities as their primary psionic talent , while their telepathic abilities , though existing , were rather below average for Betazoids . Usually the telepathy of these half - breeds , without extensive training , was limited to communication with other empaths or telepaths and full telepathic contact with emotionally very close persons ( for example , an " imzadi " ) . All full Betazoids were unable to read the thoughts of Ferengi , Breen , Ullian s , and Dopterian s , but some half - Betazoids were occasionally successful in sensing the emotions of some of these species . Additionally , full Betazoids seemed to even be able to psionically influence some of these species . ( ; ) Culture and tradition . Due to their telepathy , Betazoid culture embraced honesty almost to a point considered rude by other cultures . Lwaxana Troi , on numerous occasions , commented on her befuddlement at the Human practice of fibbing to spare others ' feelings or for politeness ' sake . ( ) While eating , Betazoids expressed thanks for their food by ringing a gong at intervals . ( ) Betazoids were likely polytheistic , as evidenced by an exclamation used by Lwaxana Troi , " " Thank the four deities you ' re here " " . ( ) Betazoids had a complex hereditary nobility ; prominent Betazoid diplomat Lwaxana Troi , for example , was " Daughter of the Fifth House , Holder of the Sacred Chalice of Rixx , and Heir to the Holy Rings of Betazed . " Betazoid tradition had children genetically bonded to a future spouse . ( ) The Betazoid wedding ceremony was seen as a celebration of love , therefore all participants ( bridegroom and guests ) were traditionally nude . ( ; ) At one time , it was fashionable for Betazoid women to wear elaborate wig s that caged small animal s . The practice , which was cruel to the animals , was stopped when one ( unknown ) woman stood up against it . ( ) The Betazoid government had matriarchal elements , comparable to the Parliament of Angel I . ( ) " In the mirror universe , the Betazoids were subjugated by the Terran Empire at some time prior to 2257 . " Captain and emperor were involved in this action . ( ) Appendices . Background information . Originally , Gene Roddenberry conceived Betazoid females as having four breasts . He was persuaded not to use this idea by writer D . C . Fontana . ( " Star Trek - Where No One Has Gone Before " paperback ed . , p . 110 ) The black coloration of a Betazoid ' s eye was achieved by the relevant performer wearing a pair of black contact lenses . The makeup team responsible for devising this method was essentially " trapped in not doing too much , " in the words of Makeup Supervisor Michael Westmore . ( ) According to the novel " Engines of Destiny " , the Betazoids were known to the Borg as Species 1599 .