"fis phenomenon" meaning in English

{
  "etymology_text": "From an incident reported in 1960 by J. Berko and R. Brown. A child referred to his inflatable plastic fish as a fis, but rejected adults' statements that used the same mispronunciation.",
  "head_templates": [
    {
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        "1": "en",
        "2": "noun",
        "head": "fis phenomenon"
      },
      "expansion": "fis phenomenon",
      "name": "head"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [],
          "source": "w"
        },
        {
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          "kind": "other",
          "langcode": "en",
          "name": "Linguistics",
          "orig": "en:Linguistics",
          "parents": [],
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        }
      ],
      "glosses": [
        "The observation that a child's perception of phonemes occurs earlier than the ability to produce them."
      ],
      "id": "en-fis_phenomenon-en-noun-Argb44S2",
      "links": [
        [
          "linguistics",
          "linguistics"
        ],
        [
          "perception",
          "perception"
        ],
        [
          "phoneme",
          "phoneme"
        ],
        [
          "produce",
          "produce"
        ]
      ],
      "raw_glosses": [
        "(linguistics) The observation that a child's perception of phonemes occurs earlier than the ability to produce them."
      ],
      "topics": [
        "human-sciences",
        "linguistics",
        "sciences"
      ]
    }
  ],
  "word": "fis phenomenon"
}

{
  "etymology_text": "From an incident reported in 1960 by J. Berko and R. Brown. A child referred to his inflatable plastic fish as a fis, but rejected adults' statements that used the same mispronunciation.",
  "head_templates": [
    {
      "args": {
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        "head": "fis phenomenon"
      },
      "expansion": "fis phenomenon",
      "name": "head"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "Pages with 1 entry",
        "Pages with entries",
        "en:Linguistics"
      ],
      "glosses": [
        "The observation that a child's perception of phonemes occurs earlier than the ability to produce them."
      ],
      "links": [
        [
          "linguistics",
          "linguistics"
        ],
        [
          "perception",
          "perception"
        ],
        [
          "phoneme",
          "phoneme"
        ],
        [
          "produce",
          "produce"
        ]
      ],
      "raw_glosses": [
        "(linguistics) The observation that a child's perception of phonemes occurs earlier than the ability to produce them."
      ],
      "topics": [
        "human-sciences",
        "linguistics",
        "sciences"
      ]
    }
  ],
  "word": "fis phenomenon"
}