Go to about any public square, and you see pigeons pecking
at the ground, always in search of crumbs dropped by a passerby. While the
pigeons’ scavenging may seem random, new research by psychologists at the
University of Iowa suggest the birds are capable of making highly intelligent
choices, sometimes with problem-solving skills to match.
The study by Edward Wasserman and colleagues centered on the
"string task," a longstanding, standard test of intelligence that
involves attaching a treat to one of two strings and seeing if the participant
(human or animal) can reel in that treat by pulling the correct string.
Pigeons on computers
In this case, the UI researchers took the pigeons into the
digital age: The birds looked at a computer touch screen with square buttons
connected to either dishes that appeared to be full or empty. If the bird
pecked the correct button on the screen, the virtual full bowl would move
closer, ultimately to the point where the pigeon would be rewarded with real
“The pigeons proved that they could indeed learn this task
with a variety of different string configurations—even those that involved
crossed strings, the most difficult of all configurations to learn with real
strings,” says Wasserman, Stuit Professor of Experimental Psychology and the
corresponding author of the study published in the journal Animal Cognition.
In experiments, the authors found the pigeons chose
correctly between 74% and 90% of the time across three varieties of string
tests. The breadth of the string tests, coupled with the pigeons’ accuracy,
suggest that virtual string tests can be used in place of conventional string
experiments—and with other animal species as well, the researchers say.In videos that the researchers took, the pigeons in many
instances scan and bob their heads along the string “often looking toward and
pecking at the dish as its moves down the screen,” the authors write,
suggesting the birds noted the connection between the virtual strings and the
“We believe that our virtual string task represents a
promising innovation in comparative and developmental psychology,” says
Wasserman, whose department is in the College of Liberal Arts and Sciences.
“It may permit
expanded exploration of other species and variables which would otherwise be
unlikely because of inadequacies of conventional string task methodology or
sensorimotor limitations of the organisms."
“These results not only testify to the power and versatility
of our computerized string task, but they also demonstrate that pigeons can
concurrently contend with a broad range of demanding patterned-string problems,
thereby eliminating many alternative interpretations of their behaviour,” the
The paper is titled, “Pigeons learn virtual patterned-string
problems in a computerized touch screen environment” and was first published
online in March. Contributing authors include Leyre Castro Stephen Brzykcy,
from the UI and Yasuo Nagasaka from the Riken Brain Science Institute in Japan.
The UI psychology department funded the study.