When confronted with a long line of people outside a restaurant, do you join the back of the queue or choose to dine elsewhere? Whilst this may seem like a snap judgment, there is more to the decision-making process than meets the eye. In fascinating work, HKUST’s Ying-Ju Chen and colleagues looked at how patience, service quality information, and preconceived ideas about others guide our decision to join a queue. Their findings have surprising implications for service operations systems and contribute enormously to the field of social psychology.

Two factors seem to persuade customers to join the back of a queue—the information they have about service quality and how willing they are to spend time waiting. In the absence of service quality information, a longer queue can signal greater demand and thus superior service quality. However, long queues can also signal poor service, which is typical of blind “buying frenzies.” “If a long queue is such a good indicator of high-quality service,” ask the authors, “why do we often observe long queues for bad service?”

To answer this question, the researchers considered a scenario in which the speed of service does not affect queue length; instead, long queues for bad service are maintained when customers hold incorrect beliefs about the people already in that queue. The estimated number of impatient people in a queue can be skewed by either “projection bias,” individuals’ belief that people are similar to themselves, or “reverse-projection bias,” which is the belief that others are dissimilar to ourselves.

To scrutinise the decision-making processes involved in joining a queue, the researchers constructed an ambitious model. They considered the effects of various customer attributes, including their level of patience, whether they have information about service quality, and the presence of projection bias or reverse-projection bias in terms of others’ patience.

The results revealed that impatient customers who have no information about service quality will—in the hope of learning from informed customers’ behaviours—wait for others to join the queue. Ironically, however, those joining the queue may be uninformed customers who are more patient.

The authors also discovered that projection bias causes impatient customers to react more sensitively to a long queue. This, they say, “leads to overestimation of the service quality and waiting in a long queue.” Under reverse-projection bias, patient customers underestimate others’ patience, overestimate service quality, and also wait in the queue. According to the researchers, “these bounded rationalities impede effective learning by inducing decision errors, which could reduce social welfare.”

Service operations system such as restaurants, call centres, and hospitals can use these insights to spin things in their favour. A service provider wishing to exploit customers’ incorrect beliefs could, for example, create a marketing campaign that exaggerates a service’s popularity. Alternatively, offering information to the public about their incorrect biases could “restore effective learning and increase social welfare by reducing suboptimal queue-joining decisions,” conclude the researchers.