Table 2. Object Permanence Tasks Following Pollok et al. (2000).

Task	Correct
1. A plastic object dangled from a transparent synthetic fiber, moving  in 180° or 360° angles around the bird several times in  counterbalanced clockwise and anticlockwise fashion.	The bird continuously followed the object in 180° arc or more.
2. As in task 1, but moving horizontally from one side behind a screen  and reappeared on the others side. Moving directions (right-left,  left-right), were counterbalanced. In addition, the fiber long enough  to keep the hand out of the birds’ eye sight.	The individual was looking at the point of disappearance or at the starting point of reappearance before the object actually reappeared.
3. An object was partly hidden under a single cover.	The bird retrieving the object by pulling it out or removing the cover.
4. An object was completely hidden under one of two different covers.	The individual removed the appropriate cover and retrieved the object.

Note. Task: Description of the experimenters demonstration. Correct: Criterion to pass a given task successfully.