They were introduced in the mid-1800s and were called “cabinet cards,” as people displayed them in cabinets in their home parlors. They were popular with performers and personalities, but also with regular citizens.

The Amon Carter Museum of American Art’s new exhibit, “Acting Out: Cabinet Cards and the Making of Modern Photography,” introduces us to the 19th-century phenomenon to show its relevance in the historic progression of photography. The subjects appear comfortable; unusual props are commonplace. Many remind us of the photos we take daily with our camera phones: pets, kids, kids with pets.

The Carter says of the exhibit, which opens Aug. 18: “Cabinet cards coaxed Americans into thinking about portraiture as an informal act, forging the way for the snapshot and social media with its contemporary ‘selfie’ culture.”

“Acting Out” consists of hundreds of photographs, many of which will be seen publicly for the first time. They’ve been sourced from not only the Carter’s own photography vault but from collections nationwide. The exhibit is divided into four parts, “Caught in the Act,” “The Trade,” “Sharing Life: Family and Friends” and “Acting Out,” which chronicles the birth and evolution of the cabinet card and traces Americans’ acceptance of the camera as a way to share moments in their lives.

“This exhibition reveals how 19th-century Americans approached photography far more playfully than ever before, a transformation that forever shifted our relation to the medium,” says John Rohrbach, the Carter’s senior curator of photographs.