Gregory Miller

New York investment banker Gregory R. Miller spends his workdays on the facts and figures of the media-merger world. At home, he surrounds himself with conceptual art, a style whose ground rules are still debated and whose pieces can be difficult to describe.

The beauty—and market value—of a piece of conceptual art tends to hinge on the intellectual heft of the idea, or concept, embedded within its creation. In 1953, when Robert Rauschenberg erased a drawing by Willem de Kooning, the blank page he left behind became its own work of art, an example of conceptualism.

The collection of Mr. Miller, president of the board of the alternative art space White Columns, includes museum mainstays like Adrian Piper, Glenn Ligon, Mark Bradford, Ghada Amer and Catherine Opie. This week, in an interview, which has been edited, Mr. Miller spoke about a few conceptual additions to his contemporary-art collection.

Gregory R. Miller recently bought works by Carroll Dunham ('[Hers] Night and Day #6')

"Carroll Dunham is constantly pushing the boundaries of what a painting can look like. My partner Michael Wiener and I bought some recent works like '(Hers) Night and Day #6,' where Dunham has painted the figure of a female nude within the traditional context of a landscape.

You can see he's included recognizable images like the woman, the sky and trees, but he's using their shapes like building blocks for something more. He's asking himself, 'Why are we still painting the human figure?'

"Last year we bought a Fred Sandback sculpture called 'Eight-Part Vertical Construction.' What we bought was eight long strings of yarn in four different colors like white, black, red and gray. The strings go straight up from the floor to the ceiling.

They're paired, but the space between some of the strings is narrow and the space between others is farther apart. When you stand back, the strings look like they're defining actual spaces as though you're looking through invisible walls. It's the same living room, but now I start to think about walking through or around it in a new way.

"And the nice thing about that yarn? Whenever it falls down, you can hire a person who's authorized by the Sandback estate to come string up another piece of yarn.

Sara Barker ('Abject Posture')

"I'm also always looking for younger artists, like Scottish sculptor Sara Barker. We own several of her bigger pieces like 'Abject Posture.' Imagine a cube, but take away its insides and all you're left with is its outlines, like the legs on a table without a solid top."