While you might not want to think much about something disgusting, our brain’s disgust response may be more revealing than you know.

Previous blogs have emphasized both the existence of universal basic emotions and the evolutionary basis behind many of our expressions. A recent article in Science helps examine these same evolutionary roots with regard to the feeling of disgust. Here, Drs. Weinstein, Buck, and Young draw parallels between the evolution of disgust and fear based on perceptions of the outside world and exposure to parasites.

In this paper, they outline how our feeling of disgust is situated within a fear of parasites. The threat of parasitic infection carries dangerous and significant risks for any individual, but they are simultaneously very hard to detect. This helps result in a series of indirect, almost heuristic, approaches to detecting them, largely relying on the disgust response.

For example, many species will simply categorically avoid feces and carcasses, sidestepping the entire issue. Others can depend on subtle, implicit cues, to try to figure out if a given carcass is infected, drawing from the chemical changes that result in an infected animal’s sweat or feces.

While these observations may stand alone in interesting ways, the analysis gets more nuanced and informative when compared to the cognitive structures that can help prey detect and avoid predators. Dr. Weinstein and her team describe this as the “predator-induced landscape of fear.”

This phenomenon describes the general outlook that many animals can create, where they integrate cues that may reveal the threat of a predator or similar sorts of stimuli. This integrates olfactory cues, for example, into a holistic way of evaluating the world based on a fear response.

Dr. Weinstein’s paper presents the notion of disgust as being part of an overall “landscape of disgust,” where numerous cues and sensory inputs can all be synthesized into a more comprehensive way of evaluating the world according to the risk of parasites.

These landscapes of disgust and of fear are also not completely different phenomena. Detecting predator feces, for instance, helps integrate both fear and disgust into the same picture. We are definitely hoping for more research that shows how perhaps other emotions are integrated in similar ways. And of course, a greater understanding of these emotions in the human context would be invaluable.

This differs, perhaps, from the way humans see themselves as intellectually evaluating the world around them.

However, psychological research helps connect these ideas with how we, as humans, rely on a complex series of heuristics in order to evaluate the world around us. Over the last two weeks, for example, our blogs have examined heuristics related to deception detection and confirmation bias. These cognitive shortcuts are rooted in survival, where we developed innate abilities to evaluate emotions without cognitive effort.

While these are different than a worldview integrated with fear or disgust, they help demonstrate how humans are not completely different. We still rely on subtle heuristics, just like animals, especially for basic emotions like fear and disgust. And critical thinking requires that we acknowledge and evaluate those heuristics.

If you expect someone to be guilty, does that make them more likely to be?

As discussed last week, many implicit biases complicate the process of determining guilt or detecting deception during an interview process. In a comprehensive trio of 2008 studies, a team of psychologists from the University of Aberdeen, United Kingdom found that expectations of guilt have a profound predictive effect on whether or not the interviewer will conclude that their subject is guilty.

Certainly, this has troubling implications on our ability to trust judgment and confront our own cognitive biases. Last week’s blog reviewed the significant impact of other sorts of biases, and these findings further complicate the matter.

Their 2008 paper compiled the results of three studies. In the first, participants were asked to act as interviewers and randomly assigned to either a guilt-expectation or innocence-expectation, which involved priming them to believe that the interviewee was more or less likely to be lying. They were then tasked with rating how confident they were about the interviewee’s guilt or innocence following a brief interview.

From this first study, the results gave clear evidence that expectations of guilt made conclusions of guilt much more likely, as well as driving a more combative “guilt-presumptive” questioning style. The study authors attribute this to the well-known phenomenon of “confirmation bias” wherein our brains tend to emphasize evidence that conforms to our expectations.

The study authors emphasize the importance of their findings on actual law enforcement practices. Many crime-related interviews are conducted when a (often reasonable) suspicion of guilt already exists, and the goal is often more about obtaining a confession than assessing guilt.

The second study varied slightly by actually recruiting participants as interviewees and subjecting them to accusations of guilt, after either assigning them to an actually guilt condition or not. In this case, rates of confession were tracked. Interestingly, presumptions of guilt did not seem to increase the likelihood of securing a confession, though actual guilt did make confessions more likely.

Finally, the third study exposed participants to recordings of previous studies’ interrogations. However, they were not told if the given interview was primed as a guilt-expectation or an actual guilty situation. Instead, they were simply asked to evaluate whether the recorded interviewee was guilty based on their behavior and tone of voice.

Fascinatingly, they found that the chief predictor of evaluations in the third study was the interviewer’s style. Suspects who responded to guilt-presumptive styles were rated as more defensive, more nervous, and more likely to be guilty, regardless of their guilt.

In sum, the first study found that interviewers are more likely to conclude guilt, if they expect it, and this was expanded by the third study’s conclusions that interviewer style contributes to other witness’ perceptions of the interviewee’s guilt. Finally, the second study, while challenging the notion that aggressive interviewing would secure confessions, found that only guilty participants were particularly likely to confess.

There are many ways to deduce whether somebody is lying during an interview process, but it is important that we critically evaluate how we are trying to detect deception. Over the last two weeks, we have outlined some common biases, such as confirmation bias, and this is exactly why having an observational process based on scanning, identifying, interpreting, and evaluating can be beneficial in any interaction.

This is precisely what we teach in our detection deception workshops, as well as in our new Reading People program.

 Is deception detection easier when we have verbal cues? Could it even be harder?

A lot of sensory input goes into our ability to detect deception, but it is hard to tease out the role of verbal and nonverbal cues. We train you to look for both, but a new study seeks to break down the question and look at exactly what helps us determine whether somebody is lying.

This research combines expertise in communications and criminology by creating an experiment where participants are exposed to an interrogation record and tasked with evaluating whether the interviewee is lying. This is varied between multiple cases where participants get a full videotape, an audio clip, or just a transcript.

This builds on research finding that we rely on mental shortcuts in order to more effectively detect deception. The study authors broke down biases into truth, visual, demeanor, and expectancy violation biases.

Each of these is relevant. For instance, truth bias leads us to assume truthfulness in others, while expectancy violation bias general sees unusual behavior as constituting a lie. Perhaps more relevant to the question at hand, visual bias emphasizes visual stimuli in detecting deception, while demeanor bias sees certain communication styles as credible ones, regardless of the truth.

Unfortunately, none of these biases are necessarily accurate measures of deception detection. In fact, one of our past blogs has pointed out that the common belief that people fail to make eye contact when lying is a myth, showing how our expectancy violation biases create problems.

By exposing participants to different levels of verbal and visual cues, the study authors sought to explore each of these biases. While past research has explored similar topics, it tends to have focused on short, less than one minute clips. This prevents an understanding as to whether interviewers can use a longer exposure to better understand deceptive behavior.

Essentially, this experiment hypothesized that the more nonverbal cues available, the more likely the participants would assess the interviewer as truthful, with the full videotape exemplifying this tendency.

Interestingly, deceivers were generally believed the most when participants had access to the audio and visual components of the interview, but this was not the case for those telling the truth. Instead, perceptions of truthfulness peaked with access to audio but began to decline when visual components were involved.

The researchers saw this as broadly confirming the important role of cognitive bias. For instance, deceivers likely paid closer attention to their demeanor (in order to hide their lie), resulting in truth-tellers being likely to showcase more unusual behavior and thus introducing the demeanor bias.

The real lesson here is that our cognitive biases may mislead us, but that doesn’t mean that heuristics are all bad news. Instead, empirical science has developed a more valid framework to rely on.

And it is that sort of framework that Humintell regularly trains people in. One great way to learn empirically-validated lie detection is to get trained in our expert techniques.