▁point ▁both ▁eyes ▁accur ately ▁enough ▁that ▁the ▁object ▁of ▁regard ▁falls ▁on ▁corresponding ▁points ▁of ▁the ▁two ▁ret inas ▁to ▁avoid ▁the ▁per ception ▁of ▁double ▁vision . ▁In ▁most ▁verte br ates ▁( hum ans , ▁m amm als , ▁re pt iles , ▁birds ), ▁the ▁movement ▁of ▁different ▁body ▁parts ▁is ▁controlled ▁by ▁stri ated ▁mus cles ▁acting ▁around ▁joint s . ▁The ▁movement ▁of ▁the ▁eye ▁is ▁slightly ▁different ▁in ▁that ▁the ▁eyes ▁are ▁not ▁rig id ly ▁attached ▁to ▁anything , ▁but ▁are ▁held ▁in ▁the ▁orbit ▁by ▁six ▁extra oc ular ▁mus cles . ▁▁ ▁Her ing ' s ▁law ▁of ▁equal ▁inner v ation ▁ ▁Sh err ington ' s ▁law ▁of ▁reci pro cal ▁inner v ation ▁ ▁Reading ▁ ▁When ▁reading , ▁the ▁eye ▁moves ▁continu ously ▁along ▁a ▁line ▁of ▁text , ▁but ▁makes ▁short ▁rapid ▁movements ▁( s acc ades ) ▁inter ming led ▁with ▁short ▁stops ▁( fix ations ). ▁There ▁is ▁considerable ▁vari ability ▁in ▁fix ations ▁( the ▁point ▁at ▁which ▁a ▁sac cade ▁j umps ▁to ) ▁and ▁s acc ades ▁between ▁readers ▁and ▁even ▁for ▁the ▁same ▁person ▁reading ▁a ▁single ▁passage ▁of ▁text . ▁ ▁Music ▁reading ▁ ▁E ye ▁movement ▁in ▁music ▁reading ▁is ▁the ▁sc anning ▁of ▁a ▁musical ▁score ▁by ▁a ▁music ian ' s ▁eyes . ▁This ▁usually ▁occurs ▁as ▁the ▁music ▁is ▁read ▁during ▁performance , ▁although ▁mus icians ▁sometimes ▁scan ▁music ▁sil ently ▁to ▁study ▁it , ▁and ▁sometimes