Numerous scientific studies investigating whether torture is effective have yielded the same result: the science shows torture doesn’t work. Repeatedly, the research shows that the torture subjects will simply lie to make their torment end. (source)
Note: Torture is illegal under the Geneva Convention which establishes the standards of international law for humanitarian treatment in war.
Interestingly, one of the most powerful pieces of evidence showing the inefficacy of torture comes out of World War 2 Germany: Hanns Scharff, a German WWII pilot interrogator, who is widely considered to be the most successful interrogator of all time.
“He has been called the “Master Interrogator” of the Luftwaffe and possibly all of Nazi Germany; and he has also been praised for his contribution in shaping U.S. interrogation techniques after the war.” (source)
Scharff was opposed to physically abusing prisoners to obtain information. Instead he used a method that literally involved “going on strolls with pilots through the countryside, offering them some baked goods and striking up friendly conversations.” (source)
During the war, Scharff was charged with interrogating many V.I.P.s (Very Important Prisoners) like senior officers and world-famous fighter aces. He interviewed roughly 500 American and British pilots- all who were highly trained in keeping secrets from the enemy. Of the 500 pilots Scharff interviewed, he failed to get the information he desired out of just 20. (source)
The Scharff Technique was defined by four key components: 1) a friendly approach, 2) not pressing for information, 3) the illusion of knowing it all, and 4) the confirmation/disconfirmation tactic. (source)
The Number 4 strategy (confirmation/disconfirmation) is when an interrogator presents a claim acting like they already know it all, and then sees if the prisoner will confirm or deny it. And it works.
“When the interrogator [Scharff] erroneously suggested that a chemical shortage was responsible for American tracer bullets leaving white rather than red smoke, the pilot quickly corrected him with the information German commanders sought. No, there was no chemical shortage; the white smoke was supposed to signal to pilots that they would soon be out of ammunition.” (source)
After the war, Scharff eventually immigrated to the United States, married an American, and had a successful career as a mosaic artist. He was invited to lecture about prisoner interrogation techniques at the Pentagon and elsewhere. (source)
Link to the book “The Interrogator” by Raymond Toliver