► We study a Grey parrot that understands cardinality and ordinality of 1–6. ► We teach the parrot two novel number labels (7,8) and their ordinality (6<7<8). ► The bird infers cardinality of novel numbers from their ordinality without training.
Grey parrot number acquisition: The inference of cardinal value from ordinal position on the numeral list
Irene M. Pepperberg, Susan Carey
Volume 125, Issue 2, November 2012, Pages 219–232