Surgery requires concrete thinking because, among other reasons, there’s no room for fudging in the OR. In order to do anything – literally, to do anything at all – in surgery, you have to ask for a precise instrument from the scrub tech. You have to know what you intend to do, and exactly which instrument you need to do it with. For reasons of both protocol and expediency, you can’t just fish through the instruments on the scrub tech’s table (can’t take your eyes off the field for so long; the table is out of arm’s reach; there’s such a huge collection of metal instruments in trays there that only the scrub tech knows where anything is; it’s very impolite to take one of the scrub tech’s instruments without asking for it; most scrubs will be eternally furious at you if you so much as touch the mayo stand instead of asking).
At the very beginning of internship, if you’re actually expected to do anything other than not get in the way during the surgery, the attending will be the one asking for the instrument and telling you what to do with it. But early on, they transition to expecting you to make at least a few simple decisions about what to do next, and what to do it with. Even the most mild-mannered attendings can go to town on the resident who doesn’t know which instrument he wants to use: “What are you going to do next, doctor? Are you going to stand there all day? Do you want to mobilize in this direction, or not? You sure you want to cut across that artery without ligating it first? Come on, doctor, your patient is bleeding; what are you going to do about it?”
So it becomes an ingrained habit of thinking: you plan ahead to accomplish a particular thing (peel the hernia sac down; get the gallbladder off the liver bed; separate the strap muscles), and you choose how you’re going to do it, and then you give instructions to the scrub tech to help it happen. No ifs, ands, or buts.
(Although there is a certain amount of leeway for not being able to name the instrument, as opposed to not knowing the shape or type of instrument you want. Choosing metzenbaum scissors vs bovie is important. Forgetting the exact name of the clamp, or not being able to pronounce it, may not be fatal, as long as you can quickly describe it enough for the tech – who probably knew what it was before you thought of it – to hand it to you. This exception does only apply for about the first two, maybe three times, that you’re in a procedure. After that, if you’re using it, you should know the name.)
(And yes, there is also a certain amount of puzzling your way through distorted anatomy. But even then, you have to at least decide which area you’re going to tackle first, and how you’re going to do that.)