The 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. However, when adults asked him, "Is this your fis?" he rejected the statement. When he was asked, "Is this your fish?" he responded, "Yes, my fis." This shows that although the child could not produce the phoneme /ʃ/, he could perceive it as being different from the phoneme /s/. In some cases, the sounds produced by the child are actually acoustically different, but not significantly enough for others to distinguish since the language in question does not make such contrasts.