they say never let a bird be higher then Eye level of the shortest member of your household because of dominance
I have noticed this on my tiels not all of them,though, when we were at our old house we moved the play gym to the living room and put it ontop of the tiels cage, this inturn made me unable to reach the very top of the play gym, so when ever a tiel was up there they refused to step up and Would run back and forth the length of the top perch of the play gym
Now when those same birds were on the cage, or the cage door, or on the couch or any where else where i was taller they steped up perfectly fine no issues at all
With my quaker if he's up higher then my b/f (which is his best friend only person who he goes to w/out biting) he will bite my b.f he will be stubborn and not want to step up
any where else where my b/f is taller he does everything fine