In the following example code both functions get called once a second. Is this along the lines of what you're trying to do?
Code:
import viz
import vizact
viz.go()
def Blink_Detection():
print 'inside blink detection'
def Region_of_Interest():
print 'inside region of interest'
vizact.ontimer(1,Blink_Detection)
vizact.ontimer(1,Region_of_Interest)