Spock performing a Vulcan mind meld.
The Vulcan mind meld (or mind touch) was a telepathic technique employed exclusively by Vulcans in which the minds of two individuals become a single entity. In the Vulcan language, it was known as Taroon-Ifla. (LUG: The Way of Kolinahr: The Vulcans)
Typically, physical contact was required for a meld, however particularly powerful melders, such as Slovaak, are capable of performing melds remotely. (ST video game: Away Team, TOS episode: "A Taste of Armageddon", TOS episode: "By Any Other Name", TOS episode: "The Omega Glory"). As they were touch telepaths, they normally conducted a mind meld by touching the bioelectrical focal points on the face which in the Vulcan language was known as the "qui'lari". (ENT novel: The Romulan War: Beneath the Raptor's Wing) Melding was a deeply personal experience, as the two minds of the meldees are entirely open to each other. However, melding can be used as an interrogation technique in which case the melder can block the meldee's access to their own mind. Those that learnt this discipline on Vulcan were required to take an oath that they would rather die before violating the privacy of another's consciousness against their will. (TOS novel: Mindshadow)
Melding can be dangerous, particularly so when conducted with a non-Vulcan but it can also be a useful tool; some neurological conditions can be cured by a mind meld. Further, melds often result in part of each of the participant’s knowledge and mental state being transferred to each other and are also the manner in which someone can deposit or obtain a katra. (TOS movie: Star Trek II: The Wrath of Khan, VOY episode: "Meld") Furthermore, it meant that memories from generations of Vulcans were capable of being passed down to their descendants and was partly responsible for the retention of ancient Vulcan traditions. (TOS novel: Captain's Glory)
Tolaris and T'Pol in a mind meld (Fusion)
Despite the practice of melding dating back to the time of Surak, by the mid-22nd century, something of a stigma had developed around melding. Those who were capable of or practiced melding were seen as an undesirable minority. As a consequence Pa'nar Syndrome, a condition contracted by melding also became taboo subject. Ironically, Pa'nar Syndrome can easily be cured by a meld with an experienced melder. Fortunately following reforms on Vulcan in 2154, melding once again became socially acceptable. (ENT episodes: "Fusion," "Stigma" and "Kir'Shara")
External Link
Mind meld article at Memory Alpha, the wiki for canon Star Trek.
