Determining characteristics such as socioeconomic status from the way a person uses language.
One Stanford linguistics professor experienced this when he first moved to Palo Alto. When he phoned using his educated, professional voice, he would be told that the house was available but the landlords would change their minds when they saw him in person. He is African American.
He is now doing research on 'linguistic profiling' showing that landlords and others can usually make out a caller's race and class just by their accent, and discriminate accordingly.
Zuraidah Ibrahim, "Don't fence them in with real estate," The Straits Times (Singapore), July 7, 2002
Closely related to handwriting analysis is the developing field of textual analysis, or forensic linguistics, in which an expert analyzes similarities between documents based not on the handwriting, but on various stylistic markers. . . . This sort of linguistic profiling was instrumental in identifying Theodore Kaczynski as the Unabomber.
Robert G. Morvillo and Robert J. Anello, "New Approaches to Expert Evidence," New York Law Journal, April 3, 2001