The following are true:
a. a horopter is a straight line on which an object will stimulate corresponding retinal points
b. objects further or nearer than the horopter to the eyes are always perceived as double
c. objects in the Panum's area are perceived singly
d. objects outside the Panum's are are perceived as double
a. a horopter is a straight line on which an object will stimulate corresponding retinal points
b. objects further or nearer than the horopter to the eyes are always perceived as double
c. objects in the Panum's area are perceived singly
d. objects outside the Panum's are are perceived as double