2024年4月1日发(作者：)

雅思ogtest8阅读答案passage3原文题目及答案解析内容

本文为大家带来雅思OGtest8阅读passage3原文题目及答案解析内容。

Left or right?

An overview of some research into liberalization: the dominance of one side of the body over the other

A

Creatures across the animal kingdom have a preference for one foot, eye or even antenna. The cause of this

trait, called liberalization, is fairly simple: one side of the brain, which generally controls the opposite side of the

body, is more dominant than the other when processing certain tasks. This does, on some occasions, let the animal

down: such as when a toad fails to escape from a snake approaching from the right, just because its right eye is

worse at spotting danger than its left. So why would animals evolve a characteristic that seems to endanger them?

B

For many years it was assumed that liberalization was a uniquely human trait, but this notion rapidly fell apart

as researchers started uncovering evidence of liberalization in all sorts of animals. For example, in the 1970s,

Lesley Rogers, now at the University of New England in Australia, was studying memory and learning in chicks.

She had been injecting a chemical into chicks brains to stop them learning how to spot grains of food among

distracting pebbles, and was surprised to observe that the chemical only worked when applied to the left

hemisphere of the brain. That strongly suggested that the right side of the chicks brain played little or no role in the

learning of such behaviours. Similar evidence appeared in songbirds and rats around the same time, and since then,

researchers have built up an impressive catalogue of animal liberalization.

C

In some animals, liberalization is simply a preference for a single paw or foot, while in others it appears in

more general patterns of behaviour. The left side of most vertebrate brains, for example, seems to process and

control feeding. Since the left hemisphere processes input from the right side of the body, that means animals as

diverse as fish, toads and birds are more likely to attack prey or food items viewed with their right eye. Even

humpback whales prefer to use the right side of their jaws to scrape sand eels from the ocean floor.

D

Genetics plays a part in determining liberalization, but environmental factors have an impact too. Rogers

found that a chick's liberalization depends on whether it is exposed to light before hatching from its egg - if it is

kept in the dark during this period, neither hemisphere becomes dominant. In 2004, Rogers used this observation

to test the advantages of brain bias in chicks faced with the challenge of multitasking. She hatched chicks with

either strong or weak liberalization, then presented the two groups with food hidden among small pebbles and the

threatening shape of a fake predator flying overhead. As predicted, the birds incubated in the light looked for food

mainly with their right eye, while using the other to check out the predator. The weakly-lateralized chicks,

meanwhile, had difficulty performing these two activities simultaneously.

E

Similar results probably hold true for many other animals. In 2006, Angelo Bisazza at the University of Padua

set out to observe the differences in feeding behaviour between strongly-lateralized and weakly-lateralized fish. He

found that strongly-lateralized individuals were able to feed twice as fast as weakly-lateralized ones when there

was a threat of a predator looming above them. Assigning different jobs to different brain halves may be especially

advantageous for animals such as birds or fish, whose eyes are placed on the sides of their heads. This enables

them to process input from each side separately, with different tasks in mind.

F

And what of those animals who favour a specific side for almost all tasks? In 2009, Maria Magat and Culum

Brown at Macquarie University in Australia wanted to see if there was general cognitive advantage in

liberalization. To investigate, they turned to parrots, which can be either strongly right- or left-footed, or

ambidextrous (without dominance). The parrots were given the intellectually demanding task of pulling a snack on

a string up to their beaks, using a co-ordinated combination of claws and beak. The results showed that the parrots

with the strongest foot preferences worked out the puzzle far more quickly than their ambidextrous peers.

G

A further puzzle is why are there always a few exceptions, like left-handed humans, who are wired differently

from the majority of the population? Giorgio Vallortigara and Stefano Ghirlanda of Stockholm University seem to

have found the answer via mathematical models. These have shown that a group of fish is likely to survive a shark

attack with the fewest casualties if the majority turn together in one direction while a very small proportion of the

group escape in the direction that the predator is not expecting.

H

This imbalance of liberalization within populations may also have advantages for individuals. Whereas most

co-operative interactions require participants to react similarly, there are some situations - such as aggressive

interactions - where it can benefit an individual to launch an attack from an unexpected quarter. Perhaps this can

partly explain the existence of left-handers in human societies. It has been suggested that when it comes to

hand-to-hand fighting, left-handers may have the advantage over the right-handed majority. Where survival

depends on the element of surprise, it may indeed pay to be different.

Questions 27-30

Complete each sentence with the correct ending, A-F, below.

Write the correct letter, A-F, in boxes 27-30 on your answer sheet.

27 In the 1970s, Lesley Rogers discovered that

28 Angelo Bisazza’s experiments revealed that