Ivory Towers: Chunks, not pieces, of eight

ALEX has been the subject of numerous studies, writes William Hartston. His communicating, conceptual, cognitive and problem-solving abilities have all been the subject of academic papers. Alex is a parrot and his current interest, as reported in 'Numerical Competence in an African Gray Parrot (Psittacus erithacus)' by Irene M Pepperberg (Comparative Psychology, 1994, No 1), is counting.

Research on humans and animals has identified two processes of enumeration: 'Subitizing' is fast and effortless, applies to collections of no more than eight objects and consists of an immediate perception of how many items are present. 'Counting' is the tedious 1,2,3 process.

What looks like counting, however, may be achieved by 'chunking', whereby a group of six is subitized as two chunks of three.

To prevent Alex's adoption of such non-counting strategies, he was tested with groups of items varying in form and colour. From a batch of blue and red keys and trucks, he was asked: 'How many blue keys?'

Under such conditions, it has been shown that humans count rather than subitize. Alex's score of 83.3 per cent accuracy suggests that he may be able to count too, but the researcher concludes: 'Determining whether Alex can count in the human sense, however, may not be especially useful.'