Twitter says it will investigate after users find its preview of a photo, with a Black person and a white person, more frequently displayed the white person (Rachel Kraus/Mashable)

Rachel Kraus / Mashable:
Twitter says it will investigate after users find its preview of a photo, with a Black person and a white person, more frequently displayed the white person  —  The first look a Twitter user gets at a tweet might be an unintentionally racially biased one.  —  Twitter said Sunday …