Questions 1-11 are based on the following
This passage is excerpted from Leyra Castro and Ed Wasserman, “Crows Understand Analogies,” © 2015 by Scientific American.
A recent research collaboration has discovered that
crows exhibit strong behavioral signs of analogical
reasoning—the ability to solve puzzles like “bird is to air as
fish is to what?” Analogical reasoning is considered to be
5 the pinnacle of cognition and it only develops in humans
between the ages of three and four.
Why might crows be promising animals to study? Of
course, crows are reputed to be clever. Aesop’s famous
fable “The Crow and the Pitcher” tells of a crow solving a
10 challenging problem: the thirsty crow drops pebbles into a
pitcher with water near the bottom, thereby raising the
fluid level high enough to permit the bird to drink. Such
tales are charming and provocative, but science cannot rely
15 Recent scientific research sought to corroborate this
fable. It found that crows given a similar problem dropped
stones into a tube containing water, but not into a tube
containing sand. Crows also chose to drop solid rather than
hollow objects into the water tube. It thus seems that
20 crows do indeed understand basic cause-effect relations.
But, what happens when crows are given problems that
require more abstract thinking? Before setting our sights
on analogical reasoning, we might begin with a simpler
abstract task. For example, sameness and differentness are
25 key abstract ideas, because two or more items of any kind
—coins, cups, caps, or cars—can be the same as or different
from one another. Because sameness and differentness can
be detected visually, perhaps that may provide an elegant
way to study their apprehension by nonverbal animals.
30 To do so, we present visual stimuli on a touchscreen
monitor. We reward animals with food for contacting one
button when sets contain identical items and we reward
animals for contacting a second button when sets contain
non-identical items. Several species of birds and mammals
35 learn this task and also transfer their learning to new
stimuli, showing that they have learned an abstract
concept, which extends beyond the training items.
Devising a task to study analogical thinking in animals
is the next step. Here, the gist of analogy can be captured
40 by arranging a matching task in which the relevant logical
arguments are presented in the form of visual stimuli.
Using letters of the alphabet for explanatory purposes,
choosing test pair BB would be correct if the sample pair
were AA, whereas choosing test pair EF would be correct if
45 the sample pair were CD. Stated logically, A:A as B:B
(same = same) and C:D as E:F (different = different).
Critically, no items in the correct test pair physically
match any of the items in the sample pair; so, only the
analogical relation of sameness can be used to solve the
Now, we have found that crows too can exhibit
analogical thinking. Ed Wasserman, one of the authors of
this article, and his colleagues in Moscow, Anna Smirnova,
Zoya Zorina, and Tanya Obozova, first trained hooded
55 crows on several tasks in which they had to match items
that were the same as one another. The crows were
presented with a tray containing three cups. The middle
cup was covered by a card picturing a color, a shape, or a
number of items. The other two side cups were also covered
60 by cards—one the same as and one different from the
middle card. The cup under the matching card contained
food, but the cup under the nonmatching card was empty.
Crows quickly learned to choose the matching card and to
do so more quickly from one task to the next.
65 Then, the critical test was given. Each card now
pictured a pair of items. The middle card would display
pairs AA or CD, and the two side cards would display pair
BB and pair EF. The relation between one pair of items
must be appreciated and then applied to a new pair of
70 items to generate the correct answer: the BB card in the
case of AA or the EF card in the case of CD. For instance,
if the middle card displayed a circle and a cross, then the
correct choice would be the side card containing a square
and a triangle rather than the side card containing two
Not only could the crows correctly perform this task,
but they did so spontaneously, from the very first
presentations, without ever being trained to do so.
It seems that initial training to match identical items
80 enabled the crows to grasp a broadly applicable concept of
sameness that could apply to the novel two-item analogy
task. Such robust and uninstructed behavior represents the
most convincing evidence yet of analogical reasoning in a