Strikingly, Alex, the 28-year-old parrot who lives in a Brandeis lab run by comparative psychologist and cognitive scientist Dr. Irene Pepperberg, spontaneously and correctly used the label "none" during a testing session of his counting skills to describe an absence of a numerical quantity on a tray. This discovery prompted a series of trials in which Alex consistently demonstrated the ability to identify zero quantity by saying the label "none."
Dr. Pepperberg's research findings, published in the current issue of The Journal of Comparative Psychology, add to a growing body of scientific evidence that the avian brain, though physically and organizationally somewhat different from the mammalian cortex, is capable of higher cognitive processing than previously thought. Chimpanzees and possibly squirrel monkeys show some understanding of the concept of zero, but Alex is the first bird to demonstrate an understanding of the absence of a numerical set, Dr. Pepperberg noted.
"It is doubtful that Alex's achievement, or those of some other animals such as chimps, can be completely trained; rather, it seems likely that these skills are based on simpler cognitive abilities they need for survival, such as recognition of more versus less," explained Dr. Pepperberg.
Alex had previously used the label "none" to describe an absence of similarity or difference between two objects, but he had never been taught the concept of zero quantity. "Alex has a zero-like concept; it's not identical to ours but he repeatedly showed us that he understands an absence of quantity," said Dr. Pepperberg.