A specialised tricorder able to produce a detailed record of everything a person has experienced over a recent period, brought to Argelius II to test Scott's lost memory.
The psychotricorder appears in the Original Series episode Wolf in the Fold. Montgomery Scott is found over the body of a murdered dancer on Argelius II with a knife in his hand and no memory of the event.
Kirk proposes a psychotricorder examination, which would give a full account of Scott's actions over the previous twenty-four hours. Lieutenant Karen Tracy beams down with the instrument and is left alone with the engineer to run it.
She is stabbed to death before the scan is complete, and Scott again remembers nothing. The inquiry moves to the Enterprise, where the ship's computer finally identifies the true killer as the entity Redjac, hiding in the administrator Hengist.