Final answer:
Convergence is the binocular cue involving eye muscle signals for perceiving depth when focusing on near objects.
Step-by-step explanation:
The binocular cue for depth perception based on signals from muscles that turn the eyes to focus on near or approaching objects is called convergence. When we look at nearby objects, our eyes rotate inward, and the greater the angle of convergence, the closer the object is perceived to be. This is different from retinal disparity, which refers to the slight differences in images between the two eyes due to their separation (interocular distance), another binocular cue that informs us about depth by comparing the images from the two retinae. Monocular cues, on the other hand, only require one eye and include factors like linear perspective, interposition, and relative size.