Instead of coming up with some abstract computerised lab task, the researchers tested their drink ordering skills and then swapped places to test how they were remembering all the orders.
Eight customers sat at a table, and ordered drinks. When the waiter brought the beverages, the scientists tallied up how many were served to the people who had ordered them, and how many delivered to someone else. All the waiters performed admirably.
The customers later ordered more drinks, then switched seats before the waiter returned. This produced dreary results. The scientists tried this on nine waiters, only one of whom consistently delivered drinks to the right people.
Interviewed afterwards, waiters said they generally paid attention to customers’ locations, faces and clothing. They also disclosed a tiny trick of the trade. They “did not pay attention to any customer after taking a table’s order, as if they were protecting the memory formation in the path from the table to the bartender or kitchen.”