"café wall illusion" meaning in English

{
  "etymology_text": "Described under its current name in 1973 by Richard Gregory, according to whom this effect was observed by a member of his laboratory, Steve Simpson, in the tiles of the wall of a café at the bottom of St Michael’s Hill, Bristol.",
  "forms": [
    {
      "form": "café wall illusions",
      "tags": [
        "plural"
      ]
    },
    {
      "form": "café-wall illusion",
      "tags": [
        "alternative"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "café wall illusion (plural café wall illusions)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Optical illusions",
          "orig": "en:Optical illusions",
          "parents": [
            "Vision",
            "Senses",
            "Perception",
            "Body",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "An optical illusion in which the parallel straight dividing lines between staggered rows with alternating dark and light bricks appear to be sloped rather than parallel."
      ],
      "id": "en-café_wall_illusion-en-noun-NcuOsaiH",
      "links": [
        [
          "optical illusion",
          "optical illusion"
        ],
        [
          "parallel",
          "parallel"
        ],
        [
          "straight",
          "straight"
        ],
        [
          "dividing line",
          "dividing line"
        ],
        [
          "staggered",
          "staggered"
        ],
        [
          "row",
          "row"
        ],
        [
          "alternating",
          "alternating"
        ],
        [
          "sloped",
          "sloped"
        ]
      ],
      "wikipedia": [
        "Richard Gregory"
      ]
    }
  ],
  "word": "café wall illusion"
}

{
  "etymology_text": "Described under its current name in 1973 by Richard Gregory, according to whom this effect was observed by a member of his laboratory, Steve Simpson, in the tiles of the wall of a café at the bottom of St Michael’s Hill, Bristol.",
  "forms": [
    {
      "form": "café wall illusions",
      "tags": [
        "plural"
      ]
    },
    {
      "form": "café-wall illusion",
      "tags": [
        "alternative"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "café wall illusion (plural café wall illusions)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English terms spelled with É",
        "English terms spelled with ◌́",
        "Pages with 1 entry",
        "Pages with entries",
        "en:Optical illusions"
      ],
      "glosses": [
        "An optical illusion in which the parallel straight dividing lines between staggered rows with alternating dark and light bricks appear to be sloped rather than parallel."
      ],
      "links": [
        [
          "optical illusion",
          "optical illusion"
        ],
        [
          "parallel",
          "parallel"
        ],
        [
          "straight",
          "straight"
        ],
        [
          "dividing line",
          "dividing line"
        ],
        [
          "staggered",
          "staggered"
        ],
        [
          "row",
          "row"
        ],
        [
          "alternating",
          "alternating"
        ],
        [
          "sloped",
          "sloped"
        ]
      ],
      "wikipedia": [
        "Richard Gregory"
      ]
    }
  ],
  "word": "café wall illusion"
}