Tours like these are important for the future of museums, Mr. Vo said in an interview later. “It makes them relevant,” he said, “and people want to see themselves reflected in collections.”

Alistair Brown, policy officer at the Museums Association, an organization for museum, gallery and heritage professionals, agreed. “More and more museums are looking at radical ways of reappraising their collections,” he said in a telephone interview. “They’re either inviting critical and diverse voices into the museum, or at least welcoming their presence if uninvited.”

The trend benefits from many years of research by museums into the background of the items in their collections, as well as decades of campaigning by minority groups to be heard, Mr. Brown added.

One of the most prominent series showing museum collections through a new lens is led by Alice Procter, a 23-year-old art historian studying for a master’s degree at University College London. Her “Uncomfortable Art” tours look at how imperialism and colonialism underpin the collections of some of London’s major cultural institutions, including the British Museum and the National Portrait Gallery.

Ms. Procter discusses, for example, how items were acquired in colonial times and paintings were used to shape national identity in Britain, which portrayed itself as a superior and benevolent society. She hands out badges featuring the slogan “Display It Like You Stole It,” and sells “Dear Art Gallery...” postcards to let cultural institutions know when labels are inadvertently racist, sexist or “totally impenetrable,” among other options.

Not everyone is pleased. The British Museum began a monthly series last year to discuss the acquisition of items in its collection, partly in response to Ms. Procter. (The next is scheduled for Feb. 8.) In April, the British tabloid The Daily Mail wrote that Ms. Procter was “using sell-out tours to label Lord Nelson a ‘white supremacist’ and brand Queen Victoria a ‘thief.’ ” She immediately began receiving threats.