The SPOT program is based in large part on the work of Dr. Paul Ekman, a retired psychology professor at the University of California, who devised a system that identifies facial "micro-expressions" and body movements that are out of the ordinary.
"Micro-expressions, the wonderful thing about them, is they're universal," Dr. Ekman told ABC News in January. "There are seven different emotions and it doesn't matter your language or your culture, if you have one of those emotions it is going to appear in your face and if you're trying to conceal it, it may well leak out in a micro-expression."
Other behavioral science experts said they were skeptical.
"The scientific research shows that it's very hard to detect whether somebody's up to no good just by looking at their behavior," Dr. Maria Hartwig, an assistant professor at John Jay College of Criminal Justice in New York and an expert in the psychology of deception and its detection, said in January.
In its conclusion, the GAO reported suggested the DHS study the viability of the SPOT program further.