Fis phenomenon is a phenomenon during a child's language acquisition that demonstrates that perception of phonemes occurs earlier than a child's ability to produce the appropriate allophone. It is also illustrative of a larger theme in child language acquisition: that skills in linguistic comprehension generally precede corresponding skills in linguistic production. The name comes from an incident reported in 1960 by J. Berko and R. Brown, in which a child referred to his inflatable plastic fish as a fis.