absent, inattentive, abstracted, scatty, forgetful, scatterbrained, thoughtless, befuddled, klutzy, thickheaded, more...

mindful, attentive, observant

forgetful, scatterbrained, distracted, preoccupied, spacey, zoned out, more...

not thinking,   not looking,   blank mind,   being distracted,   not fully there,   being forgetful,   mind somewhere else,   very forgetful,   not entirely there,   mind is off