I noticed this, over the few years I've been playing guitar, when I see someone else shred, they hold the pick as such that their middle, ring, and little fingers are extended, whilst when I'm playing they're curled up. Is there something behind that or just preference?

Takamine Gs330S
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Ibanez TS9DX
Line 6 Tonecore Uber Metal
just preferance i play with my fist closed aswell and aslong as its comfortable to you and it dosnt effect your playing then its no problem at all
Are they resting those extended finger on the guitar body? If they are, thats anchoring, which is bad, if they are just extended in the air not touching anything, thats simply preference. I both extend my fingers and curl them in depending on what strings im playing and what I feel like doing.
no its just preference
i play with my fingers outsretched, but 2 of my friends play with their fingers curled up
so go with whichever way u prefer
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Line 6 Uber Metal
I always play with my hand open. I have very long fingers and when I try to play with my hand closed like a fist the knuckles of my ringfinger and pinky tend to hit the strings.
"Don’t be a guitarist. Be a musician."

Steve Howe
I play with my hand open and rest my pinky on the body. I know alot of people say it's bad, but it's preference. Alot of players do it.

When I try to play with a closed fist I just can't play, I hit the strings with my knuckles and it feels ****.