Feeding pigeons serial chunks.

Feeding pigeons serial chunks

Pigeons usually leave their mark on public statues and parkbenches, but they have now left their mark on the study of a basic principle of human memory. Lists that can be organized into memorable units or "chunks" are easier for people to remember, and psychologist Herbert S. Terrace of Columbia University in New York City reports in the Jan. 8 NATURE that pigeons possess a similar, nonverbal capability. Since a bird does not need language to engage in memory chunking, Terrace says it "is a more primitive and biologically pervasive cognitive process than has been recognized previously."

In initial trials, he trained 25 pigeons to receive a reward offood by pecking five colors or shapes in the correct sequence. The task, says Terrace, is comparable to many instances in which humans use rote memory, such as punching in a seven-digit number on a pushbutton telephone. Lists in which colors and shapes were clustered into chunks were learned twice as rapidly as lists consisting only of colors or containing interspersed colors and shapes. After learning a sequence, the pigeons were much better at recognizing the correct order of an internal pair of symbols that bridged two chunks than the correct order of an internal pair from a single chunk.

Although pigeons appear to memorize experimentally presentedsymbols in chunks, Terrace says it is not known if an animal can chunk items that are not organized into patters by a researcher.