When I really put my mind to it, I can recall precisely eight telephone numbers in full, including that of Radio York, a station I haven't listened to in years, and not including those of several of my closest friends. This causes me very few problems. The numbers I need are stored in my phone, while similar technological crutches exist for almost every imaginable form of data.

Being able to recite the kings and queens of England means little, surely, compared with knowing where to find that information online in a matter of seconds, along with all the presidents of America, 30 recipes for spaghetti carbonara, the full text of Paradise Lost, and pretty much anything else. To invest precious time and energy enhancing my capacity for rote learning would seem eccentric. But such eccentrics do exist. The most talented (and, apparently, the most eccentric) spend their lives on the competitive memorisation circuit; the endearingly geeky world that Joshua Foer sets out to explore in this witty and revelatory book.

"Anyone could do it, really," Ben Pridmore, thrice winner of the World Memory Championships, observes in the opening pages, referring to his ability to memorise the order of a shuffled deck of cards in 32 seconds, and to recite pi to 50,000 decimal places. Foer decides to put that claim to the test, and to his own astonishment ends up winning the US National Memory Championships. (This is not a spoiler: the book's jacket reveals it.) Perhaps anyone can do it, then – or at least the sharp-brained, Yale-educated younger brother of the novelist Jonathan Safran Foer can. But the deeper question animating his adventure is why anyone would want to. Is this all just party tricks? Or in losing the ability to memorise, are we losing something essential to being human?

That worry dates back to the invention of one of the very first memory crutches: writing. "Socrates feared that writing would lead the culture down a treacherous path of intellectual and moral decay," Foer explains. "Because even while the quantity of knowledge available to people might increase, they themselves would come to resemble empty vessels." The key technique still used by today's memory champions, known as the "memory palace", is ancient, too. Credited to the Greek poet Simonides of Ceos, it involves remembering sequences of words by imagining objects placed around a physical setting you know well, such as your home.

"The thing to understand, Josh, is that humans are very, very good at learning spaces," says Ed Cooke, the ebullient British memory grand master who becomes Foer's coach, talking him through the exercise in order to remember a shopping list featuring such items as pickled garlic and cottage cheese. "For your first memory palace, I'd like you to use the house you grew up in . . . I want you to close your eyes and try to visualise in as much detail as possible a large bottle of pickled garlic standing right where the car should be parked." Then, proceeding to the front door: "I want you to imagine Claudia Schiffer swimming in [a] tub of cottage cheese . . ." Even the supermodel aspect dates back centuries: sexual images are more memorable. "If you wish to remember quickly, dispose the images of the most beautiful virgins into memory places," advised Peter of Ravenna, a 15th-century writer on the topic.

The secret to an amazing memory, then, is essentially a trick. (The book's title refers to another vivid image Foer concocted for a similar exercise.) Truly photographic memories – Lisbeth Salander from Stieg Larsson's Millennium series notwithstanding – are now largely considered to be a myth. The key is to link what we're poor at remembering (words, numbers) to what we're good at remembering (environments). To those of us who can't remember phone numbers but who can recall almost perfectly the floor plan of the infants school we attended, this makes eminent sense.

In itself, however, the act of memorising things does not provide limitless journalistic colour, and it is Foer's detours down other side-streets of memory that make for some of the book's most compelling moments. In California, he meets the retired lab technician known in the psychological literature as EP, a victim of such catastrophic amnesia that, like the British musician and documentary subject Clive Wearing, he forgets almost everything almost immediately – including, of course, the fact of his forgetting. At this extreme frontier of non-remembering, the centrality of memory becomes clear. EP (who died before the book was published) is as focused on the present as any Zen monk, and seems happy enough. But rich human relationships are fundamentally beyond his reach: they are built on shared memory and, as Foer puts it, cannot sustain themselves solely in the present tense.

Among those least charitably portrayed is Tony Buzan, the British memory impresario, who as one of the founders of the World Memory Championships hovers behind much of the action. "Everything about Buzan gives the strong impression of someone wanting to make a strong impression," Foer writes of the globe-trotting guru, who claims to have the highest "creativity quotient" in the world, and who annoys other memory specialists with his fondness for scientific-sounding but preposterous statements. (An example: "Very young children use 98% of all thinking tools . . . by the time they're teenagers, they're down to 50%.") After pleading busyness, he eventually grants Foer an interview, in his chauffeur-driven 1930s taxicab, en route to his Thames-side estate. "Buzan is – as he often found occasion to remind me – a modern Renaissance man . . . his latest collection [of poetry] consists entirely of poems written on and about his 38 transatlantic flights aboard the supersonic Concorde," the author notes dryly.

Studious practice of the memory palace technique and others, under Cooke's guidance, ultimately catapults Foer to his surprise victory in the US competition, during which he memorises a pack of cards in one minute and 40 seconds. "You are now the undisputed owner of the brains of America!" an ecstatic Cooke tells him, though he does so by phone, having by now decided to relocate to the University of Sydney to study the philosophy of cricket. ("He was also working on inventing a new colour," we learn.) Foer advances to the world championships, but performs poorly. Neither the victory nor the defeat seem to bother him much either way, and this sense that he's not especially committed to the competitive memorisation lark is his book's only significant fault. But it is a minor one; his broader journey certainly demonstrates how much memory matters, even if it's hard to make the case that memorising, say, 107 first and last names and their associated faces from photographs in 15 minutes – another feat Foer pulls off – matters quite as much.

Apart from anything else, filling up our mental storehouses in the right way can make life feel longer. "Creating new memories stretches out psychological time, and lengthens our perception of our lives," Foer explains. This is why it's important to travel to new locations and try new activities, and it makes intuitive sense that a well-exercised memory, practised at retaining information, might be able to maximise that lengthening effect.

He even ends up endorsing the wisdom that lies behind Buzan's bluster. Memorisation has a bad reputation in education today, dismissed as antithetical to creativity. But we don't need to choose between abandoning it entirely, on the one hand, or retreating into Michael Gove-ish calls for a return to the old days of chanting British monarchs by rote. The truth lies in the middle: a supple memory provides the basis for retaining the information from which creative new ideas can then be forged. Besides, Foer adds, "what I had really trained my brain to do, as much as to memorise, was to be more mindful, and to pay attention to the world around me. Remembering can only happen if you decide to take notice." It is a point that lingers in the memory, alongside the image of Claudia Schiffer in a tub of cottage cheese.

Oliver Burkeman's Help!: How to Become Slightly Happier and Get a Bit More Done is published by Canongate.