Editing Depth perception (section)

=== Motion parallax ===
{{main|Parallax}}
When an observer moves, the apparent relative motion of several stationary objects against a background gives hints about their relative distance. If information about the direction and velocity of movement is known, motion parallax can provide absolute depth information.<ref>{{cite journal |author=Ferris SH |year=1972 |title=Motion parallax and absolute distance|journal= Journal of Experimental Psychology |volume=95 |issue=2 |pages=258–263|url=http://archive.rubicon-foundation.org/xmlui/bitstream/handle/123456789/8713/NSMRL_673.pdf?sequence=1|archive-url=https://web.archive.org/web/20190209232805/http://archive.rubicon-foundation.org/xmlui/bitstream/handle/123456789/8713/NSMRL_673.pdf?sequence=1|url-status=usurped|archive-date=February 9, 2019|doi=10.1037/h0033605 |pmid=5071906 }}</ref> This effect can be seen clearly when driving in a car. Nearby things pass quickly, while far-off objects appear stationary. Some animals that lack [[binocular vision]] due to their eyes having little common field-of-view employ motion parallax more explicitly than humans for depth cueing (for example, some types of birds, which bob their heads to achieve motion parallax, and squirrels, which move in lines [[orthogonal]] to an object of interest to do the same<ref>Kral K. (2003). [http://wexler.free.fr/library/files/kral%20(2003)%20behavioural-analytical%20studies%20of%20the%20role%20of%20head%20movements%20in%20depth%20perception%20in%20insects,%20birds%20and%20mammals.pdf "Behavioural-analytical studies of the role of head movements in depth perception in insects, birds and mammals"]. ''Behavioural Processes'' '''64''': 1–12.</ref>).<ref name="parallax" group="note"/>