In Interrogations, Video Calling Could Help Interpret Nonverbal Cues Without Influencing Them

video calling in interrogations

Lies are such an innate part of human existence that the ability to deceive is woven into our central nervous system. Our bodies don’t even treat the act as an unnatural one, and the processes that go on inside our brains are all but indistinguishable between truth and lie.

So complex and subtle is the act of lying that even the most advanced, voice-based truth detection systems are best used in combination with a visual assessment of a person’s entire body.

As such, video conferencing could become the next big weapon detectives use to assess suspects and witnesses during their search for truth.

A Trial by Ordeal

The search for truth revealed in the human body dates back centuries to an ancient Chinese discovery that lying was somehow linked to stress. The science of detection, however, remained a rather blunt and often violent process until the late 19th century when actual scientists posited that the key emotion was fear, and begun watching for changes in blood pressure, pulse, breathing, and galvanic activity on the skin.

All of this led to the arrival of the famed polygraph test, which is still in use today by law enforcement, the FBI, and the CIA, although few states allow its use in court, at least not without consent from both defense and prosecution.

The problem with the polygraph–aside from the whole debate about whether it actually works–is that it is considered something of a trial by ordeal. Interviews can take three hours, and the tools used to measure the body’s responses are intrusive. It’s also very difficult to administer, even in expert hands.

That makes its use problematic for police departments trying to use it regularly during their investigations.

But there is a simpler way.

Our Voices, Not Our Words, Betray Us

The current primary source of inquiry in truth detection is the voice. Researchers have discovered that the truth often leaks out in the way we speak under examination, far more than it does in the words we say. Tell-tale signs of stress manifest in our speech when we’re under stress, and these can be used to appraise the honesty of what we’re saying.

NITV, the makers of one such truth verification device, claim that their innovation has an accuracy greater than 95%. It captures changes in the voice regardless of speech pattern or language, and picks up cues far too subtle for the human ear to detect.

The device is usually deployed via a microphone attached to a subject, but it is sensitive enough to work over the phone, and even on audio recordings.

However, such is our human ingenuity for lying that even the makers of this cutting edge technology mention that an assessment of facial expression, posture, and other nonverbal cues is still useful in truth assessment.

This is where video conferencing comes in.

Body Language Interpretation

What detectives are looking for, even when deploying technology like voice-stress analysis, is a cluster of behaviors.

Movements like touching the face, shrugging the shoulders, or shifting in a chair are not significant on their own, but when they occur in quick succession they can be signs of stress and unease.

And when a detective is in the midst of an interview that may hold life and death consequences for a victim or a suspect, their own physical interaction with a subject can interfere with the body language of the interviewee–the detective’s status counts, even in the middle of interrogation. It’s also known that, to gain the trust of whomever they’re talking to, humans will naturally mimic the posture, speaking speed, and speech inflections of the other person in the conversation, and it seems likely that good liars are better at this than most people.

So let’s remove the detective from the room altogether.

Interrogation by Video Call

Instead, let’s place the person of interest in the presence of a computer screen and conduct the interview by video conference. The voice-stress analysis equipment can still be used, but now the detective is a step removed from the suspect and better able to interpret their words and actions without influencing them.

Such a setup would allow other detectives, police body language experts, and your voice-stress analyst to watch on in real-time, perhaps even with cameras set up at different angles to capture the entire scene.

One detective might want to watch with the sound muted, specifically focusing on nonverbal cues, while voice-analysts focused entirely on the vocal, and interviewing detective zeroed in on the actual verbal content of the call.

The process could also be repeated across distance so that investigators could speak with the family, employers, and associates of a suspect, keeping the key detectives at the helm of the investigation without sending them flying across the country.

Deployed with the speed of a phone call, detectives could have a web of inquiry spread across the country quicker than you can say “I’m telling the truth”.

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