SHE looks as innocuous as Miss Marple, Agatha Christie’s famous detective.

But also like Miss Marple, Julia Hirschberg, a professor of computer science at Columbia University, may spell trouble for a lot of liars.

That’s because Dr. Hirschberg is teaching computers how to spot deception — programming them to parse people’s speech for patterns that gauge whether they are being honest.

For this sort of lie detection, there’s no need to strap anyone into a machine. The person’s speech provides all the cues — loudness, changes in pitch, pauses between words, ums and ahs, nervous laughs and dozens of other tiny signs that can suggest a lie.

Dr. Hirschberg is not the only researcher using algorithms to trawl our utterances for evidence of our inner lives. A small band of linguists, engineers and computer scientists, among others, are busy training computers to recognize hallmarks of what they call emotional speech — talk that reflects deception, anger, friendliness and even flirtation.