Buenos Aires boasts impressive waiters, whose minds are worth studying, according to the paper Strategies of Buenos Aires Waiters to Enhance Memory Capacity in a Real-Life Setting, published in the journal Behavioural Neurology.

"Typical Buenos Aires senior waiters memorise all orders from clients and take the orders, without written support, of as many as 10 persons per table. They also deliver the order to each and every one of the customers who ordered it without asking or checking."

And most of the time, they get it right.

How do they do it? Researchers Tristan Bekinschtein, Julian Cardozo and Facundo Manes ran an experiment to find out. The three are based variously at the Institute of Cognitive Neurology and at Favaloro University, both in Buenos Aires, and at the MRC Cognition and Brain Sciences Unit in Cambridge.

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."

In preparing their study, Bekinschtein, Cardozo and Manes discovered a published account of a remarkable waiter who had trained himself to "recall as many as 20 dinner orders, categorise the food (meat or starch) and link it to the location in the table. He also used acronyms and words to encode salad dressing, and visualised cooking temperature for each customer's meat and linked it to the position on the table."

The Buenos Aires waiters, in contrast, "reported systematically that they have not thought of any particular strategy and that their great ability comes only with time and practice".

The best waiter – the one who delivered drinks correctly even when customers had swapped seats – claimed that, unlike his colleagues, he ignored where customers sat, and paid attention only to their looks. His professional experience, he said, "had been mostly in cocktail parties for 10 years, where people tend to change their position in the room; only in the last three years had he been working in the restaurant".

(Thanks to Diego Golombek for bringing this to my attention.)

• Marc Abrahams is editor of the bimonthly Annals of Improbable Research and organiser of the Ig Nobel prize