My deficiency is common manners. I think it's a lack of attention to the world outside of my own thoughts. I've been known to just wander away from a conversation that is clearly not over to the other participants. I notice a sneeze about 10 seconds too late to say "bless you!". I'm appropriately thankful, but assume that's clear without my actually saying or writing something to convey the feeling. Depending on the context, my preoccupation leads me to be perceived as everything from a lovable nerd to an arrogant jerk. It's something I'd like to change.