▁as ▁brain w aves , ▁heart ▁function , ▁breath ing , ▁mus cle ▁activity , ▁and ▁skin ▁temperature . ▁▁ ▁Direct ▁Visual ▁Fe ed back ' s ▁method ▁applies ▁more ▁directly ▁to ▁impro ving ▁exterior ▁physical ▁health ▁and ▁performance . ▁Instead ▁of ▁using ▁techn ically ▁advanced ▁meas uring ▁instruments ▁for ▁feedback , ▁D VF ▁re lies ▁on ▁the ▁human ▁eye . ▁One ▁method ▁that ▁has ▁been ▁used ▁to ▁test ▁D VF ▁is ▁by ▁placing ▁a ▁las er ▁beam ▁on ▁the ▁hand ▁and ▁connecting ▁it ▁to ▁a ▁monitor , ▁when ▁the ▁tra ine e ▁ra ises ▁his ▁arm ▁from ▁wa ist ▁height ▁to ▁shoulder ▁height ▁he ▁is ▁focused ▁on ▁the ▁external ▁reference ▁showing ▁exactly ▁what ▁path ▁the ▁arm ▁took ▁from ▁point ▁A ( wa ist ▁height ) ▁to ▁point ▁B ( should er ▁height ). ▁Studies ▁have ▁shown ▁that ▁not ▁only ▁is ▁a ▁higher ▁level ▁of ▁performance ▁often ▁achieved ▁faster ▁with ▁an ▁external ▁rather ▁than ▁an ▁internal ▁attention ▁focus , ▁but ▁the ▁skill ▁is ▁retained ▁better . ▁ ▁References ▁ ▁Medical ▁image ▁computing ▁and ▁computer - ass isted ▁inter vention : ▁M IC CA I ▁ 2 0 0 4 , ▁ 7 th ▁international ▁conference , ▁Saint - M alo , ▁France , ▁September ▁ 2 6 – 2 9 , ▁ 2 0 0 4 ▁H utch inson ▁S ., ▁G . ▁D . ▁H ager ▁and ▁P . ▁I . ▁Cor ke , ▁A ▁T utorial ▁on ▁Visual ▁Ser vo ▁Control . ▁IE EE ▁Trans . ▁on ▁Rob ot ics ▁and