A humanoid species with no experience of many emotions, who sent ambassadors to the Enterprise to study concepts such as pleasure, antagonism and love.
The Iyaarans are humanoids who took part in a cultural exchange with the Federation in Liaisons. Their own society lacked familiarity with several basic emotional experiences, so their ambassadors set out to study them directly. Loquel explored pleasure with Deanna Troi, sampling food with great enthusiasm, while Byleth tested Worf's patience to learn about antagonism.
The third ambassador, Voval, crashed a shuttle with Jean-Luc Picard on a planet and took the form of a stranded woman named Anna, keeping Picard captive to study romantic love. When the deception was revealed, the Iyaarans explained the experiment and parted from the Federation on peaceful terms.