Counter Terror Gazette

The Screening of Passengers by Observation Techniques Programme: analysing the issues

14 Jun 2011

The ability to identify people whose aim is to threaten aviation security before they actually strike, by simply observing their behaviour, would offer a significant breakthrough in aviation security. Whilst this idea may sound like it has been borrowed from George Orwell’s novel 1984, it is in fact a real programme now in operation at 161 US airports.

The Transportation Security Administration (TSA) developed and implemented the Screening of Passengers by Observation Techniques (SPOT) programme following the 9/11 attacks as an airport-based counterterrorism strategy aimed at deterring and preventing terrorists from boarding commercial aircraft and causing harm (GAO, 2010). The SPOT programme is designed to identify potentially high security risk individuals by screening travellers for behaviours that may be indicative of stress, fear or deception (GAO, 2010; Karp, 2010). Behaviour Detection Officers (BDO), who are responsible for implementing SPOT, utilise non-intrusive behaviour observation, analysis and detection techniques to screen travellers for involuntary behavioural reactions exhibited in response to the fear of being discovered (TSA, 2006; TSA, 2010).

Does it Work?

Whilst in principle SPOT may offer a breakthrough in the way aviation security works, in practice there is little evidence of either its effectiveness or efficacy. Despite deploying approximately 3,000 BDOs at a cost of about $212 million annually, the Transportation Security Administration’s SPOT programme has failed to detect a single terrorist (GAO, 2010). Although it is possible that the SPOT programme has fulfilled its mandate extremely well by deterring would-be terrorists, a deterrence argument is weakened by the fact that 16 individuals with terrorist involvement have travelled through 8 SPOT airports on 23 different occasions undetected by the Behaviour Detection Officers (GAO, 2010). We suggest that this apparent lack of effectiveness is not surprising given that there is little scientific evidence that humans can detect intent to deceive on the basis of nonverbal behaviour observation and analysis techniques.

Detection Accuracy

Whilst parents often appear to know whether young children are lying or hiding something, humans in general are not particularly good at detecting deception by observing behaviour. For example, on average, both laypersons and professional lie catchers perform only slightly better than average when attempting to detect the deception/truth of people unknown to them (Vrij, 2008). In other words, the simple flip of a coin may be almost as useful in detecting deception.

Behavioural Cues and Microexpression Detection

One aspect of SPOT training involves teaching BDOs how to detect microfacial expressions of emotion based upon Paul Ekman’s research on deception detection (GAO, 2010). Microfacial expressions are split-second emotional expressions on a person’s face that may reveal concealed emotion indicative of true feelings (Ekman, 2006; GAO, 2010).

Although the idea of micro-expressions has attracted much attention – they were argued to have been observed when Bill Clinton referred to ‘having not had relations with that woman’ – many researchers are dubious about the science upon which they are based. For example, independent researchers have been unable to replicate Ekman’s results on facial coding, suggesting that there is little support for the use of microexpression analysis as a terrorist detection tool (Weinberger, 2010). Most peer-reviewed research on microexpressions was published in the 1970s and 1980s and very little of Ekman’s later research on microexpressions has been peer-reviewed by other experts in the field. Without peer-review, it is difficult to assess the validity and reliability of Ekman’s research findings because it is not known if the information reported is accurate or erroneous.

Another criticism is that the majority of research on microexpressions is not relevant to the SPOT context because most of Ekman’s work has focused on the facial expressions that accompany spoken lies and not the microexpressions of deceptive individuals waiting in line at an airport security checkpoint.

There are other issues associated with the use of microexpression analysis as a terrorist detection tool. For instance, terrorists may be able to effectively suppress microexpressions with training (in the same way that many people can be trained to beat a polygraph test), some individuals may naturally exhibit microexpressions whereas others may not, and the frequency of occurrence of microexpressions is unknown. Similarly, microexpressions last a fraction of a second and may be undetected by BDOs. In fact, BDOs who blink at the moment a microexpression occurs will miss it and even if BDOs can detect split-second microexpressions it is not known how many travellers are showing suspicious microexpressions and are not being noticed. It may even be possible to suppress microexpressions with the use of the cosmetic enhancer, Botox.

There is no evidence that terrorists will exhibit the same specific behavioural response across all situations, or across all individuals, which calls into doubt the reliability of any observed indicators. It is also possible that terrorists may not display any behavioural indicators of stress, nervousness, fear, apprehension or guilt, due to their beliefs or moral disengagement from their intended actions. Furthermore, many behavioural cues may occur for reasons unrelated to deceptive intent (e.g., fear of flying or fear of crowds), thus innocent travellers may therefore show the same nervous behaviour as terrorists.

Individual and Cultural Differences

The BDO’s task of detecting truth/deception through observation may be further complicated by individual and cultural differences. Some individuals may characteristically exhibit deceptive behaviours regardless of whether they are actually being truthful or deceptive and other individuals are exceptionally good at deceiving as a result of inherent acting skills.

Associated with personality traits, the non-verbal behaviour of expressive individuals conveys an impression of truthfulness whereas the natural behaviour of self-conscious, introverted and socially anxious individuals leaves an impression of deception. As BDOs are not exposed to each traveller’s normal baseline behaviour, BDOs will be prone to making judgment errors. The use of SPOT indicators allows particular nonverbal behaviours to be interpreted as suspicious without determining whether these behaviours are a natural part of a traveller’s ordinary behaviour. The result is that terrorists with naturally expressive behaviours may remain undetected and travellers with naturally suspicious behaviours may be at risk of being falsely identified as a potential security threat.

Similarly, cultural differences can influence behaviour and thus detection accuracy. BDOs may be more accurate in detecting behaviours of travellers from their own cultural group and less accurate in detecting behaviours of travellers from more disparate cultural groups due to an in-group advantage. Behavioural differences between Western cultures and other traveller cultures raise the potential for cross-cultural non-verbal communication errors where non-verbal behaviours that are typical for an ethnic group/culture may be misinterpreted by American BDOs as suspicious or deceptive in situations where BDOs and travellers are from culturally dissimilar groups.

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