What details stand out as particularly true to life in Updike's A & P? What does this close attention to detail contribute to the story?

Updike really is a master of sensual description, allowing readers to see, hear, feel, taste and smell the surroundings created in his writing. He studied to be a visual artist which may partly explain his deft style in describing how things look. In this story, one of his most famous, the physical descriptions of the girls and the store are very naturalistic and authentic. The first-person narration is also reliable because it is not hard to imagine this teenage grocery store employee who has memorized the inventory and layout of the store, but who is also bored with his job and becomes excited when something out of the ordinary happens, especially if it involves teenage girls.

One line that describes an aisle the girls walk down says: "they all three of them went up the cat-and-dog-food-breakfast-cereal-macaroni-rice-raisins-seasonings-spreads-spaghetti-soft drinks-crackers-and-cookies aisle." The ease with which he names the items found in this aisle says he is intelligent, observant and has also made an effort to learn his job. But the description also hints at the dull sameness and regimented atmosphere of his job, in which he is expected to memorize the location of items. Anyone who has worked a retail job of this kind can relate to this idea. The store is an oppressive environment and so when he quits impulsively we know he has perhaps been waiting to find the courage to do so.

The narrator also describes what he calls the usual thoughts and behavior of shoppers in a very evocative way: 

I bet you could set off dynamite in an A & P and the people would by and large keep reaching and checking oatmeal off their lists and muttering "Let me see, there was a third thing, began with A, asparagus, no, ah, yes, applesauce!" or whatever it is they do mutter.

His perception of shoppers' thoughts, as well as the way he notices the girls and the way they shake up "business as usual" at the A & P, shows a narrator who is profoundly sensitive and observant. These descriptions ultimately are a very revealing look at the narrator who may well be based upon Updike himself.