The first thing we should consider when examining lying is the differing cognitive aspects of the liar and truth teller. The truthful person knows they didn’t do the crime, while the liar knows they did and must hide that information from others. It is also likely the liar has mentally thought about ways to commit the incident, effectively mentally practicing before committing the crime.
In these practice rounds, the liar likely considered the possible results of their actions ranging from success to being caught. Thinking about the worst outcomes brought them to consider the ways they might successfully commit the act and engage their accusers if necessary. What excuses, alibis, or explanations might work if things go badly?
Omission
To protect themselves, the liar must give away as little information as possible since they can only guess at what facts the interviewer may possess. The truth is then a useful strategy, omitting the awkward facts linking them to the crime while including things that actually happened. For example, someone might say, “My wife came home for dinner and then headed back to work. I never heard from her after that.” They omitted that they killed her right after dinner, which is why they never heard from her again.
Omission is the most common and easiest lie to use since it relies on the truth that is easily remembered and filled with details that don’t have to be created. Fabrication on the other hand is problematic because it must stand up to investigation. For example, “My mother gave me a check for that amount.” An examination of Mom’s checking account reveals that there was no check written, and the deposit made by the fabricator into their account was not made by check, but the exact cash denominations missing from the safe.
It is much easier to take a previously experienced event and use that to cover a missing time span. “I was watching TV at the time. It was an on-demand episodes of [blank].” Since the person had seen the episodes at some point, they know the content, unlike a film never seen. One is safe to use, while the other is not.
Details
The prudent liar must at some point consider their story, construct an alibi, or create explanations for their actions and prepare them, at least in some form, in advance of being questioned. Depending on the events surrounding the incident, the liar may have some inkling of possible evidence or difficulties they may face. In our experience, liars most often develop a “table of contents” version of their story—an outline if you will—that forms the structure of what they will say. The easiest way to do this is in a chronological fashion starting at the beginning and working toward its conclusion. This table of contents view of the story lacks details, making it a stripped-down version but at least giving it a structure.
The problem for the liar is in details of their outline. The general chronological structure makes retelling the story in a consistent manner less difficult but requires the deceiver to invent details to probing questions they had not known they would need. This is where the story will require the liar to handle the increased cognitive load and resulting emotions as they create, evaluate, and discard possible answers. Each of these details must be evaluated against what has been said and what was going to be said. This requires time.
In general, the truthful person retrieves this information from their memory with little effort and appears spontaneous and engaged, while the liar often delays, seeming distant as they tell their story. If the information is contained in their table of contents, the liar may also appear spontaneous as well, but as the investigator drills down into the story, the difficulties start.
The truthful story will generally contain a wealth of details. Some of these details may not impact the story to any great degree but are simply part of their memory. “I got about halfway across the parking lot and dropped my keys in a puddle.” These details could also include unforeseen interruptions or complications that interrupt the actual narrative and are likely to be included in a liar’s story.
The truth teller may also talk about their feelings as the event was unfolding. These feelings are an integral part of the truth teller’s memory and are generally lacking in a liar’s narrative of the events.
The Surprise Interview
The table of contents script doesn’t usually exist for spontaneous interviews since the liar didn’t know they were going to need to lie. Field interview situations are a perfect example since the officer literally dropped out of the tree in front of the subject. This surprise interview likely triggered a massive physiological and psychological explosion internally that overwhelms the rational mind’s search for plausible answers while making any attempt to control their physical behavior more difficult. In addition, there may be evidence readily available that makes any explanation implausible, such as a gun sitting in the passenger seat.
The field interview is the highest stakes emotionally in part because of the surprise, but also because there is a lack of preparation for questioning. The liar is going along with no thought to being stopped and questioned when the unthinkable happens—they are going to be questioned. There may be drug or alcohol impairment, which further complicates things for the subject. Then add an increased fear of detection, having to think hard of something plausible with no time to prepare, and the body running at ten thousand RPM in a fight or flight response, all of which contribute to an untenable situation for the liar.
People often appear nervous when they are uncertain about the outcome of an encounter. The body language is likely to look unnatural, magnified by nervousness and the fight or flight response. Plus, there may be movements appearing to conceal contraband that don’t fit the actions of most people encountered, thus triggering the suspicion of the investigating officer.
Most people appear nervous at the outset of a field interview. Those who are hiding contraband, have warrants, or drugs stay nervous until the evidence is uncovered. For a simple traffic offender, they only want to avoid a ticket for speeding and once the officer says he is issuing a ticket, there is nothing left to hide and the nervousness ceases. However, with the hidden issue of contraband or warrant still outstanding, there is no relief for the offender since there is still something they must conceal.
Liars versus Truth Tellers
Truth tellers tend to seem more engaged in their stories while deceivers seems flat, distant, and removed from emotions in the telling. Liars also may appear more tense, less cooperative, and negative than those telling the truth. While it is the intent of both the liar and the truth teller to be believed, the truth teller seems more natural except when they fear that they may not be believed.
In general, individuals who are attempting to lie do much less talking than truth tellers when offering a narrative or general responses to questions being asked. There is likely to be a difference between the facts offered by a deceiver versus someone telling the truth. The facts are much more likely to be verifiable in a truthful statement than those offered by a deceiver. A liar might say, “I got it from some guy over on Fifth Street. I don’t know his name, but I think I heard someone call him Slim.” On the other hand, the truth tellers statement offers verifiable information. “I got it from my next-door neighbor, Fred. You can ask him; he’ll tell you.”
People telling the truth offer stories that are generally logical and plausible. In the first several tellings of the story, truthful people may jump around as they remember details they had omitted. It is only after a number of tellings that their story becomes chronological, including the details that they had been asked previously about in their proper order. This type of narrative is extremely difficult for the liar to tell since there is no real memory associations, and it would be unlikely that it would be found in a fabricated story.
The liar has often developed a prepared narrative that was constructed from beginning to end, so the linkage between details was prepared in only one direction, making it difficult should the interviewer break the narrative and ask the individual to go forward or backward from a particular point. In addition, the liar’s story may also sound illogical, making the listener reflect on the plausibility of the narrative.
People telling the truth tend to sound much more certain about the story than the deceiver who uses pauses and repeated words during its telling. The more people talk about the incident and expand the narrative, the more obvious the differences between the liar and truth teller will likely be.
People who are offering lies are reluctant to admit that they may have forgotten something or were incorrect in some statement that they made. On the other hand, truth tellers often correct themselves when they have made a mistake or when they realize something they said was not quite right. In the same way, truth tellers readily admit when they can’t remember the answer to something, while the liar is more reluctant to do so. It should be noted that sometimes the liar will have independent recollection of everything before and after the incident but not be able to answer questions about what went on during the event.
When describing conversations in their narrative, the truth teller will use a back-and-forth dialogue giving the conversation of both parties. These conversations will generally follow the words and vocabulary used by the parties. The liar will generally be vague about the dialogue simply saying, “He yelled at me, and we talked.”
The liar must deal with and control their emotions especially in high-stakes situations. This control of emotions may result in the liar’s body appearing stiff with a lack of movements, gestures, and smiles that appear forced and unnatural. Liars in a high-stake situation also generally make less eye contact than a truth teller, possibly as a result of their uncertainty and discomfort with the situation.