Hypnosis

Hypnosis was a psychological technique. It produced a trance-like state in which one was relaxed and more susceptible to suggestion. One who hypnotizes was called a hypnotist.

Specifics
Hypnosis relaxed a person's inhibitions and was a delicate process. (SS TOS (The Business, As Usual, During Altercations))

Alpha hypnosis would not force someone to break their own morals, but could alter their perception or understanding of an event. 

It is a popular method of restoring repressed memories. 

It could be used to verify the truth of reported statements. 

Injured Vulcans could initiate a type of self-hypnosis to focus their efforts on physical repair. 

Human self-hypnosis is possible. 

History
In the 20th century, hypnosis was used to examine people reporting to have been abducted by extraterrestrials. 

In 2266, the M-113 creature hypnotized its prey before striking. 

Spock and Leonard McCoy attempted unsuccessfully to hypnotize the crew of a Vinithi ship by modifying a sonic hypnosis-inducer to affect their physiology. 

In 2267, Kor thought that the Organian phenomena of weapons radiating at high temperatures was an affect of hypnosis. In 2269, Spock theorized that Organians were expert hypnotists, and what they'd perceived on Organia was a result of hypnotism rather than reality. 

In the 2260s, after being knocked out by small drones, James T. Kirk awoke apparently hypnotized. He walked into a cave and climbed into a stasis chamber as if he were in a trance. 

In 2267, an hypnotic song was heard by James T. Kirk. He lashed himself to the mast of a Homeric ship the way did thousands of years ago, in order to hear the song without obeying its hypnotic message to commit suicide. 

In 2270, Leonard McCoy performed hypnosis on Pavel Chekov as a means to help him imagine being Harry Mudd, to help track down Mudd's Superstella. McCoy was uneasy tampering with the officer's inhibitions, but Chekov said he trusted the doctor not to harm him. It worked – Chekov suggested the planet Sarai, and Mudd was located in that sector. (SS TOS (The Business, As Usual, During Altercations))

In February 2274, Captain Morgan Avery suspected that the armed mobilization of Husians on Hus-24 against Starfleet was a result of hypnotism by their spiritual leader, Edrem. 

In 2285, hypnosis by Dr. Krista Sivertsen was unable to reveal to James T. Kirk why he thought he was a participant in the events recounted in the novel . 

In the 2340s and 2350s, Starfleet Academy's Priam IV test was required for graduation. It involved hypnotizing cadets into believing a scenario was real. 

In 2364, Deanna Troi hypnotized Beverly Crusher and Worf to restore lost memories. 

In 2366, Geordi LaForge recreated three mythological s on the holodeck to hear their hypnotic song. 

In 2375, Beverly Crusher used hypnotism to treat Colin Blakeney's temporal shock. Hypnosis allowed Blakeney to accept Data, Deanna Troi and Crusher as participants in holodeck simulations of his past, in order to help him reintegrate his memories. 

In 2376, The Doctor was susceptible to hypnosis. 

Hypnotists

 * Beverly Crusher
 * Edrem (possibly)
 * Forbus
 * Lorelei
 * M-113 creature
 * Leonard McCoy
 * Rigelian hypnoid
 * Rycho (possibly)
 * s
 * Krista Sivertsen
 * Starfleet Academy (Priam IV test)
 * T'Pelak
 * Deanna Troi
 * Carl Wentworth

Hypnotic agents

 * alpha hypnotape
 * Andronican mind-control
 * hypnoscan
 * neopenothal
 * riatine
 * servo
 * sodium pentathol
 * sonic hypnosis-inducer
 * Venus drug