The Catastrophic Impact of Halo Error
Idealization of experts, saints, and geniuses is dangerous for everyone.
Posted April 6, 2020 | Reviewed by Lybi Ma
It is now widely recognized that the only way out of the pandemic is through science and expertise. It will be through the development of tests and vaccines that we control the spread and prevent a recurrence. Scientific expertise is also required to control the spread of Covid-19 before the vaccine has been developed. But while governments use experts for considering what to do now, they should be wary of the halo effect.
The halo effect is the tendency for a good impression of someone to spread to all his or her qualities. “I like someone,” suggests that, “What s/he says is true or sound or reasonable.” In this context, I am interested in a more specific form of the halo effect as it applies to experts. Someone, for example, a behavioral psychologist, provides useful pointers to influence people’s behavior without exerting force or passing legislation. An obvious example is evidence from the field of choice architecture, where small changes in the environment influence behaviour. Having people sign tax forms at the start was found to “nudge” them to be more honest. Such studies are difficult to replicate and when they are replicated, the effect size varies widely; however, the government decision to re-design tax forms was reasonable and based on evidence.
The halo effect can be seen when someone with proven expertise in, say, behavioral psychology, gives advice without having the same (or any) evidential basis. The people he or she is advising do not pick up on this, because, having conferred, legitimately, the label “expert” on that advisor, all advice is seen as expert. The position of expert acquires the halo effect – or, more accurately, the halo error.
This error is very different from problems both the American and British people have recently had as a result of their governments dismissing “experts.” The halo error does not disrespect evidence and expertise, but it wrongly assumes that all advice coming from someone who has expertise is expert advice. In all probability, the person giving advice believes that, too. “Expert” has become part of his or her identity. As this person speaks, there is a rhythm, a sense of knowledge, perhaps what Stephen Colbert called “truthiness,” a general evidence-free feeling of truth.
When the UK government delayed imposing self-isolation and claimed that their delay was based on expert evidence about “behavioral fatigue”. This was the theory that people would, at a well-defined point, tire of the constraints and defy them, possibly just at the point when mingling would be most dangerous.
On March 16, 500 behavioral psychologists have written an open letter demanding to see the evidence that self-isolation at the earliest possible date would lead to “behavioral fatigue” and noncompliance at any particularly dangerous point in the future.  Publication of advice to the Government refers to estimates of "initial compliance" thereby suggest that compliance levels fall after a time, but as far as I am aware, evidence of this has not been presented.
Without being privy to advisory discussions, it is difficult to know whether the government was duped either by their own halo error (“These people are expert behavioral psychologists, so what they say is scientifically sound”) or by the experts’ internalized halo error (“I am an expert and therefore what I say must somehow emerge from an evidence base”). Of course, it could be both.
It is also possible that what the experts said was misinterpreted, misconstrued, or distorted, which would suggest that the halo around "expert" is being used to "dress up" a view that was not actually given by experts. In this case, the hope presumably is that the public will succumb to the halo effect.
Tragic examples of the halo error come in many different guises. Some priests were able to rape children because parents and communities believed that someone with spiritual gifts would be holy in everything he did. The halo error protected the rapist and silenced the victims. Fabulous musicians and film producers and actors whose work gave joy to others were allowed privileged access to young people including children because the halo error obscured evidence that otherwise would have signaled danger.
A common response to a halo's disintegration is expulsion. We expel the person from our midst. In some cases, this is necessary. Some criminal behavior makes further use of his or her good qualities impossible. But the current practice of canceling out from society anyone whose misdeeds were protected by the halo error can lead to another error, the horns effect. This assumption that someone who has done bad things has nothing good to offer anyone, and whose good work cannot be appreciated, actually reinforces the halo error. The horns effect, like the halo error, works on the assumption that once a person has either halo or horns, we do not have to judge individual actions or beliefs or advice. If we are to overcome the halo error, we have to take on the hard work of assessing what's before our eyes.