Passenger behavior regarding discriminatory screening varies: study


Some airline passengers impacted by airport security policies have expressed serious concerns about equity and fairness in secondary screening. Nonetheless, many are willing to make only limited sacrifices in terms of convenience, cost, and safety to avoid what they perceive as being inequitable security-screening procedures, according to a new study conducted by the University of Southern California (USC).

Called ‘Valuing Equal Protection in Aviation Security Screening’ and published in the journal Risk Analysis, the study was based on the responses of 222 participants to an online survey. They were recruited through Amazon Mechanical Turk (AMT), because previous studies indicated AMT samples were generally more representative than other population samples.

In terms of gender, 106 or 47.7 percent of the participants were female and the rest were male. From an ethnicity standpoint, 81 percent of respondents were Caucasian, 7.7 percent were Asian, 6.3 percent were African-American, 4 percent were Hispanic and 1 percent were of other ethnicities.

The study did not explore whether a more diverse mix of ethnicities among the respondents – i.e., higher proportions of minorities compared to the actual respondent sample, which contained a higher proportion of Caucasian people than actually exists in the overall US population – would have provided different findings overall. However, the study’s authors pointed out in their paper that a previous study had found White respondents were willing to make smaller (or lower) trade-offs for equity. “This is probably because Whites perceive themselves as being at a lower risk of being selected for an additional screening,” the authors note.


 Study respondents were presented with a series of trade-off assessments in which they chose between two hypothetical airlines for a vacation flight. The two airlines were identical in all aspects except that they had different security-screening policies. The first airline required all passengers to undergo the same thorough screening check (one-stage screening). However, the second airline not only required all passengers to undergo quick one-stage screening, but also required some passengers to undergo secondary screening based on one of three selection procedures.

Respondents were then randomly assigned to one of three two-stage screening procedures: one which selected people at random for secondary screening; a second which evaluated passengers according to behavioral indicators such as perceived fear or stress; and a third that focused inequitably on demographic characteristics such as age, race, sex and/or national origin.

Each study participant watched a four-minute video that described the study and explained the “equity premium”. This is defined by the study’s three authors as including monetary costs – in other words, the security-screening fee passengers are willing to pay per flight; and wait time, defined as the length of time in minutes passengers wait to complete security screening. Additional components of the equity premium include convenience, defined as the proportion of passengers without contraband who are mistakenly singled out for further scrutiny; and safety, defined as the acceptable percentage of passengers who board with contraband not detected during screening.

These equity premiums were tied both to the relatively thorough, one-stage screening procedure used by one of the two airlines and also the two-stage screening the other airline required for some passengers. The first carrier’s one-stage screening was designed to be more equitable than the other airline’s two-stage screening – two of three types of which were inequitable – but also more expensive and more inconvenient for most people, or less safe in each trade-off assessment.

The results show that equity premiums varied greatly across respondents, with many indicating little willingness to sacrifice to avoid inequitable screening (which was discriminatory in that it did not offer equal protection to all passengers), and a smaller minority willing to sacrifice anything to avoid discriminatory screening.

However, the study also found there were no significant differences between Caucasian respondents and non-Caucasian respondents in terms of their willingness to sacrifice from the standpoint of the security fees they were willing to pay or their tolerance for screening wait-time.

“We did not conceptualize the concept ‘equity premium’ as an indication of individual belief about his or her personal risk,” the study’s authors noted. “Rather, the premium reflects the extent to which one is concerned about the general principle of equal protection. Thus, it is not surprising that we did not find a significant difference in the equity premiums between White and non-White respondents.”

For all selection procedures, respondents were willing to pay up to $15 and tolerate an increase of up to two additional passengers boarding with contraband, to avoid inequitable screenings. Respondents assigned to procedures that selected passengers at random or according to their behavior were only willing to wait an additional five minutes for first-stage screening to avoid secondary screening.

But when selection procedures focused secondary screening on demographic characteristics, the study found respondents’ behavior was clearly different. Respondents were willing to wait an additional 15 minutes for first-stage screening in order to avoid inequitable second-stage screening – a delay three times as long as they were willing to accept for the other two types of secondary screening.

The study also found women were willing to wait longer and pay more than men to avoid inequitable screening. Women were 2.8 times more likely than men to agree to wait longer than the minimum wait time and 1.7 times more likely to pay more than the minimum screening fee.

“We know that travelers value both safety and equity, but what we did not know is how they reconcile these conflicting priorities,” says Kenneth Nguyen, a quantitative-methods psychology graduate student at USC who is the lead author of the study. “The value of the current research is to shed light on how travelers make this trade-off and, perhaps more importantly, uncover factors that affect this trade-off, and suggest ways that stakeholders can incorporate these findings in the design of security policies.”

Asked for comment on the study’s findings, Robert Mann, principal of aviation consulting firm R.W. Mann & Company, says in an e-mail to RGN that he sees the equity premium described by the study as equating to “willingness and cost (time and money) to invest in ‘pre-externalizing’ (pre-paying-for, if you will) portions of the security screening process by sharing enough personal data with TSA to avoid repeated treatment [in being regarded] as ‘nominal risk’.”

“The same is true of Global Entry (and the Canadian equivalent NEXUS) for Customs and Border Protection pre-vetting, a far more costly process involving a personal interview,” says Mann. “Being regarded as “’High risk’ is something else entirely, based on intelligence/information outside the normal airline buying/traveling process, such as appearance on a terrorism watchlist, ‘chatter’, prior history of smuggling, etc.”

However, “Although my position remains that 100 percent of the traveling public deserves the less intrusive processes involved in traveling with Pre-Check, most infrequent customers do not see the value in becoming vetted via Pre-Check,” writes Mann. “In effect, the ‘equity premium’ is cumulative and integrates over a traveler’s frequency of use, including the knowledge that family members traveling with the Pre-Check passenger in most cases are offered Pre-Check services as well, without having to pre-qualify. So I see the ‘concern’ as having been raised and resolved by [the] offer of Pre-Check (and Clear), which mostly only frequent travelers see as having value … greater than the ‘equity premium’.”

That said, “The major concern is that selective security-screening procedures violate the constitutional principle of equal protection, since the chance of being selected for additional scrutiny is not uniformly distributed across passengers,” Mann points out. “This concern has never been resolved.”

Addressing the issue of discrimination in airport security screening, the study’s authors note, “To our awareness, there has been no study that compares how individuals react to different alternative screening procedures. Nonetheless, we expect that respondents would react most strongly against a selection procedure based on demographic information. This is because singling out travelers by individual characteristics (without telling them the reasons) is likely to be perceived as a discriminatory act. We expect a weaker reaction against randomized screening because the procedure by which every passenger has an equal chance of being selected for additional screening is probably perceived as being more equitable.”


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