When Dominique Leca wanted feedback on his Sparrow mail mobile app in 2010, he sought out Mr. Brichter.

WSJ: Loren Brichter, a High Priest of App Design

Mr. Brichter "has this ability to put himself in the shoes of a five-year-old who tells you in an elaborate language what he's having a hard time doing, " says Mr. Leca, who now works at Google.

WSJ: Loren Brichter, a High Priest of App Design