Truth-default theory
It was developed upon the discovery of the veracity effect - whereby the proportion of truths versus lies presented in a judgement study on deception will drive accuracy rates.
This idea suggests that people presume others to be honest because they either don't think of deception as a possibility during communicating or because there is insufficient evidence that they are being deceived.
[1] Emotions, arousal, strategic self-presentation, and cognitive effort are nonverbal behaviors that one might find in deception detection.
While experimenting with deception detection, Levine found that, even in high suspicion situations, truth-bias still occurred.
Studies have shown that people who are successful at detecting deception either receive a confession by the deceiver or has some preexisting knowledge of the situation.
[10] Parks and McCornack had observed the same pattern amongst dating partners, and so they shortened the name to "truth bias," and added it to their causal model.
In subsequent works, McCornack and fellow deception scholar Timothy Levine broadened its inclusiveness to enfold a general tendency toward judging the communication of others as truthful.
This concept is also referred to as The Projective Motive Model, or the idea that individuals are less vulnerable to deception when they are already suspicious of the communication.
[12] Nonverbal manipulation of one's truth bias depends on a person's physical presence and ability to "sell" untruthful communication.
Behaviors that go against the social norm of truth telling such as teeth grinding, averting eye contact, and abnormally stretching, create the perception of deception.
Other factors that may influence a person's accuracy of deception detection include the falsifiability and infrequency of reported events.
There are several reasons behind why we are incapable of detecting deception, one of the most significant being the fact that not all people show the same tell tale signs when they are lying.
"[17] It was found that the probing effect was held when the senders behavior was controlled and the explanation was resided in receiver cognition.
[8] If the probability of predicting deception was truly 50%, then with repeated trials, the influences of both truth bias and the veracity effect would be negated and eventually the accuracy of detection would become an even 50%.
The Adaptive Lie Detector account (ALIED)[18] argues that people do not default to believe information is true.
When individuating cues are highly diagnostic (e.g., Pinocchio's nose is a perfect predictor of his deception), ALIED claims that people rely on this information heavily to make their decision, but when these individuating cues are unreliable (e.g., the speaker avoids eye contact, which is not a reliable clue to deception[19]), information about statements in general weighs more heavily into forming the decision.
Because people tend to tell the truth more often than they lie (e.g., [20]) and because individuating cues are typically not diagnostic,[19] ALIED argues that this is why people are biased to believe others show the truth bias: it is not a default of honesty (as TDT would claim), but an adaptive and functional decision that reflects the best understanding one can obtain when the cues in the environment are not very diagnostic.
When considering the demeanor of an approachable or well liked person, socialization or character training comes to mind for people who are defined as well-demeaned.
While TDT implies that humans have a truth bias when sending information, IMT addresses in detail the perspective of the sender.
A humans mind is flexible enough to adapt in certain situations when needing to be deceptive, there are just certain variable and time restraints that arise from it.
People are most prone to lie after engaging in a depleting task, when they are sleep deprived, and later in the day compared to when they first wake up.
[25] Timothy R. Levine, a Communication studies scholar at the University of Alabama at Birmingham states that several effects, models, and mini-theories comprise the truth-default theory.
