Tweet
"Can I go back?"
"No, you can't go back yet"
И это не "фотошоп", это была действительно умная птица ...
http://en.wikipedia.org/wiki/Alex_(parrot)
Alex (1976 – September 6, 2007)[1] was an African Grey Parrot and the subject of a thirty-year (1977–2007) experiment by animal psychologist Irene Pepperberg, initially at the University of Arizona and later at Harvard University and Brandeis University.
In July 2005, Pepperberg reported that Alex understood the concept of zero.[18] If asked the difference between two objects, he also answered that; but if there was no difference between the objects, he said “none", which meant that he understood the concept of nothing or zero.[19] In July 2006, Pepperberg discovered that Alex's perception of optical illusions was similar to human perception.[20]
