Telepathic memory retrieval is a process practiced by Ullian researchers. It involves using their telepathic abilities to retrieve and expand lost or faded memory engrams of an individual. The memory is then available to both the Ullian and the individual being probed.
By 2368 a group of Ullians including Tarmin, Jev, and Inad were using the procedure to gather memories from several cultures and many planets, including the Gentons, Melina II, Nel III, and Hurada III, for the construction of a memory library, which was hoped to be not unlike a collection of oral histories. The Ullians did not want to force or coerce a subject into participating; to do so would constitute telepathic memory invasion.
The group visited the USS Enterprise-D in that year, while en route to Kaldra IV. Keiko O'Brien participated in a retrieval conducted by Tarmin, during which she recovered lost memories of her grandmother. Jev later used a memory retrieval on Counselor Deanna Troi in order to implicate his father in several cases of memory invasion, when in fact Jev was guilty of the crimes. (TNG: "Violations")