In addition, star colour is simulated for noticeably red, blue and yellow stars, along with the changing brightness of three variable stars Algol, Mira and Delta Cephei.

ECONOMIST: The joys of indoor star-gazing

Alex (his name supposedly an acronym for Avian Learning Experiment) eventually learned the names of about 50 objects, knew the numerals from one to six, could perform simple addition and used categories such as similarity and difference, shape, colour and material.

ECONOMIST: Alex the African Grey