All Cues Combined
The perceptual system may 
infer the distance to the 
pyramid from convergence 
information about the 
cylinder’s distance and retinal 
disparity information about the 
depth between the cylinder and 
the pyramid.

Now that we have considered 
each possible cue to depth 
separately, we can ask the 
question of how the cues might 
work collectively in order to 
yield perception of the third 
dimension in daily life. We do 
not know the answer to this 
question. We can only surmise 
on the basis of logical 
considerations and general 
observations. For example, it is 
plausible to infer that the 
availability of several cues 
would lead to more reliable and 
accurate perception than just 
the availability of a single cue. 
Thus it is probable that the 
joint action of the oculomotor 
cues and stereopsis is quite 
effective at relatively near 
distances and more so than any 
one of these in isolation from 
the others. It is probable that 
when all known pictorial cues 
are present in a scene (or 
picture) the depth effect is 
stronger than when only one 
such cue is present. 
Stereograms based on 
photographs containing 
pictorial cues are more 
effective than those based only 
on geometrical line drawings. 
Moving pictures add depth to 
"frozen" static displays 
undoubtedly by virtue of the 
kinetic depth effect and 
motion-perspective effects they 
produce. Stereo movies 
approach the depth achieved 
under natural conditions in 
daily life.