"cheerleader effect" meaning in English

{
  "etymology_text": "First used by the fictional character Barney Stinson (Neil Patrick Harris) in \"Not a Father's Day\", an episode of the TV series How I Met Your Mother, first broadcast in November 2008.",
  "head_templates": [
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      "args": {
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      "expansion": "cheerleader effect",
      "name": "en-noun"
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  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
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          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
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      "glosses": [
        "A form of cognitive bias that causes individuals to appear more attractive to an observer when they are in a group."
      ],
      "id": "en-cheerleader_effect-en-noun-5eK6tXgK",
      "links": [
        [
          "cognitive bias",
          "cognitive bias"
        ],
        [
          "individual",
          "individual"
        ],
        [
          "attractive",
          "attractive"
        ],
        [
          "group",
          "group"
        ]
      ],
      "wikipedia": [
        "How I Met Your Mother",
        "cheerleader effect"
      ]
    }
  ],
  "word": "cheerleader effect"
}

{
  "etymology_text": "First used by the fictional character Barney Stinson (Neil Patrick Harris) in \"Not a Father's Day\", an episode of the TV series How I Met Your Mother, first broadcast in November 2008.",
  "head_templates": [
    {
      "args": {
        "1": "?"
      },
      "expansion": "cheerleader effect",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
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        "English multiword terms",
        "English nouns",
        "English nouns with unknown or uncertain plurals",
        "Pages with 1 entry",
        "Pages with entries"
      ],
      "glosses": [
        "A form of cognitive bias that causes individuals to appear more attractive to an observer when they are in a group."
      ],
      "links": [
        [
          "cognitive bias",
          "cognitive bias"
        ],
        [
          "individual",
          "individual"
        ],
        [
          "attractive",
          "attractive"
        ],
        [
          "group",
          "group"
        ]
      ],
      "wikipedia": [
        "How I Met Your Mother",
        "cheerleader effect"
      ]
    }
  ],
  "word": "cheerleader effect"
}