In addition, the user is free to move his/her eyes around rolling centers 215 and 216 while continuing to see {HEAD ~ computer} generated {TAIL ~ imagery} 
generated
In addition , the user is free to move his / her eyes around rolling centers 215 and 216 while continuing to see { HEAD ~ computer } generated { TAIL ~ imagery }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL