Unlike your pet dog or cat, zoo animals are exposed to many unfamiliar humans every day. Because visitors may affect primate behavior or welfare, it is important to understand the zoo animal-visitor relationship for these species. 

Ms Rachel Bloomfield and Professor Paul Hemsworth from the University of Melbourne used a preference test to investigate how visitors affect Melbourne Zoo's five Orang-utans.   They found that the Orang-utans spent more time on the uncovered side of the window than the covered side. Furthermore, when on the uncovered side, the animals spent more time directly looking at the viewing area than looking away.

Interestingly, both orangutans and humans appeared to prefer the right side of the window being uncovered (as opposed to the left).

The findings of this study support previous research that shows primates do not
avoid close visitor contact. In fact, visitors may be preferred stimuli and have an enriching effect on Orang-utan behaviour.

The method of testing animal preferences by manipulating enclosure variables has not been used previously and is a promising development in zoo studies.