Distractions in Meditation Upon asking questions previously, I wondered some things about my meditation. In meditation, I often experienced greatly reduced thoughts, almost no thoughts; but, the sensations at the tip of the nose are almost always lacking. 

Is it possible that, despite the absence of thoughts, something other than arising cognitions pulls my attention away from the meditation object?

Just to be clear: I am asking what specifically are the type of possible distractions which may arise in meditation. I'm also wondering what is the relative strength of these distractions, for example: does a single thought break concentration? Does paying attention to some external object merely once break concentration?
Welcome to the in-betweens!  When someone starts meditating, there are generally a few phase that they will pass through.  These are all well documented, though I personally think they find the best expression in the 10 Ox herding pictures from Zen.  The first is quieting the mind.  In the series of Ox herding pictures, this is the state of seeing and taming the ox where the mind's unruly nature is first seen for what it is it's thrashings are subdued: 

 

Once the mind settles, however, there is a very lengthy process of riding the ox to the mountain:

    

This seems to be where you are at now.  Take special note of that second painting.  I selected this artist's rendition specifically because I think it beautifully characterizes this phase of training.  The adept is riding the ox backwards.  He literally has no idea where he's going.  Indeed, this stage of training is very much categorized by a feeling of bumping around in the dark.  And it can go on for years.  Or it can be over in a matter of days.  There is literally no way of knowing how long it will take.  The adept doesn't even know if there is a mountain awaiting him!  He has no idea what's ahead!

The only thing you can actively do at this stage is practice with sincerity. Sit daily for at least an hour.  Apply your mind to your object of meditation.  Don't worry about what is a distraction and what isn't. The mind is entirely too complicated to sort those things out at this stage.  Moreover, much of what drives us into distraction is completely unconscious!  As you go forward, you might even find your mind filled with thoughts again as deep, forgotten memories or unseen, habitual obstacles begin to rise to the surface.  Lastly, I would strongly suggest that you go on retreats of three days or more.  This will go a long way to loosening the hold those subtle, unseen, and unconscious distractions have on your mind.  As they begin to fall away, your concentration will strengthen almost seemingly without effort.  

If your practice has sincerity, eventually you will arrive at the foot of the mountain.  You just have to persist.