Table of Contents
Left or Right?
Passage
A. Creatures across the animal kingdom have a preference for one foot, eye or even antenna. The cause of this trait, called lateralisation, 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 it’s 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 lateralisation was a uniquely human trait, but this notion rapidly fell apart as researchers started uncovering evidence of lateralisation 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 same time, and since then, researchers have built up an impressive catalogue of animal lateralisation.
C. In some animals, lateralisation 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 lateralisation, but environmental factors have an impact too. Rogers found that a chick’s lateralisation 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 lateralisation, 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? In2009,MariaMagat and Culum Brown at Macquarie University in Australia wanted to see if there was general cognitive advantage in lateralisation. 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 coordinated 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 Vallortigora 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 lateralisation 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 portly 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
Questions 27-30
Complete each sentence with the correct ending. A-F, below.
A. lateralisation is more common in some species than in others.
B. it benefits a population if some members have a different lateralisation than the majority.
C. lateralisation helps animals do two things at the same time.
D. lateralisation is not confined to human beings.
E. the greater an animal’s lateralisation, the better it is at problem-solving.
F. strong lateralisation may sometimes put groups of animals in danger.
Questions 31-35
Complete the summary below. Choose ONE WORD ONLY from the passage.
Lesley Rogers’ 2004 Experiment
Lateralisation is determined by both genetic and 31_____________ influences. Rogers found that chicks whose eggs are given 32_________________ during the incubation period tend to have a stronger lateralisation. Her 2004 experiment set out to prove that these chicks were better at 33________________ than weakly lateralized chicks. As expected, the strongly lateralized birds in the experiment were more able to locate 34 ________________ using their right eye while using their left eye to monitor an imitation 35_______________ located above them.
Questions 36-40
Reading Passage 3 has eight paragraphs, A-H.
Which paragraph contains the following information?
36. description of a study which supports another scientist’s findings.
37. the suggestion that a person could gain from having an opposing lateralisation to most of the population.
38. reference to the large amount of knowledge of animal lateralisation that has accumulated.
39. research findings that were among the first to contradict a previous belief.
40. a suggestion that lateralisation would seem to disadvantage animals.
Answers
Below are the answers, key words and full explanations for the IELTS Reading passage Left or Right? (Passage 3, Questions 27–40). Note: in Questions 36–40 a paragraph letter may be used more than once.
Questions 27–30: Matching Sentence Endings (A–F)
27. In the 1970s, Lesley Rogers discovered that …
Answer: D — lateralisation is not confined to human beings.
Key words: 1970s, Lesley Rogers, discovered
Explanation: “For many years it was assumed that lateralisation was a uniquely human trait, but this notion rapidly fell apart … in the 1970s, Lesley Rogers … was studying memory and learning in chicks.” Finding lateralisation in chicks shows it is “not confined to human beings.”
uniquely human trait fell apart = not confined to human beings.
Answer: D
28. Angelo Bisazza’s experiments revealed that …
Answer: C — lateralisation helps animals do two things at the same time.
Key words: Bisazza, feeding, predator
Explanation: “strongly-lateralised individuals were able to feed twice as fast … when there was a threat of a predator looming above … process input from each side separately, with different tasks in mind.” Feeding while watching for a predator = doing two things at once.
different tasks in mind / feed while watching predator = do two things at the same time.
Answer: C
29. Magat and Brown’s studies show that …
Answer: E — the greater an animal’s lateralisation, the better it is at problem-solving.
Key words: Magat and Brown, parrots, puzzle
Explanation: “the parrots with the strongest foot preferences worked out the puzzle far more quickly than their ambidextrous peers.” Stronger lateralisation → faster puzzle-solving matches E.
strongest foot preferences worked out the puzzle quickly = greater lateralisation, better problem-solving.
Answer: E
30. Vallortigara and Ghirlanda’s research findings suggest that …
Answer: B — it benefits a population if some members have a different lateralisation than the majority.
Key words: Vallortigara, Ghirlanda, mathematical models
Explanation: “a group of fish is likely to survive a shark attack with the fewest casualties if the majority turn together … while a very small proportion of the group escape in the direction that the predator is not expecting.” A minority behaving differently benefits the whole group.
small proportion escape differently = some members have a different lateralisation; fewest casualties = benefits a population.
Answer: B
Questions 31–35: Summary Completion (ONE WORD ONLY) — Rogers’ 2004 Experiment
31. Lateralisation is determined by both genetic and __ influences.
Answer: environmental
Key words: determined by, genetic and
Explanation: “Genetics plays a part in determining lateralisation, but environmental factors have an impact too.“
Answer: environmental
32. … chicks whose eggs are given __ during the incubation period tend to have a stronger lateralisation.
Answer: light
Key words: eggs, incubation period, stronger lateralisation
Explanation: “a chick’s lateralisation depends on whether it is exposed to light before hatching … if it is kept in the dark … neither hemisphere becomes dominant.” Light before hatching produces lateralisation.
exposed to light before hatching = eggs given light during incubation.
Answer: light
33. Her 2004 experiment set out to prove that these chicks were better at __ …
Answer: multitasking
Key words: 2004 experiment, better at
Explanation: “In 2004, Rogers used this observation to test the advantages of brain bias in chicks faced with the challenge of multitasking.“
Answer: multitasking
34. … the strongly lateralised birds … were more able to locate __ using their right eye …
Answer: food
Key words: locate, right eye
Explanation: “the birds incubated in the light looked for food mainly with their right eye, while using the other to check out the predator.“
looked for food with their right eye = locate food using their right eye.
Answer: food
35. … while using their left eye to monitor an imitation __ located above them.
Answer: predator
Key words: imitation, above them, left eye
Explanation: “the threatening shape of a fake predator flying overhead … using the other [eye] to check out the predator.” “Fake” = imitation; “flying overhead” = located above them.
fake predator flying overhead = imitation predator located above them.
Answer: predator
Questions 36–40: Matching Information (Paragraphs A–H; letters may repeat)
36. Description of a study which supports another scientist’s findings.
Answer: E
Key words: study, supports another scientist
Explanation: Paragraph E: “Similar results probably hold true for many other animals. In 2006, Angelo Bisazza … set out to observe … fish.” Bisazza’s fish study supports Rogers’ earlier chick findings.
similar results / Bisazza’s study = supports another scientist’s findings.
Answer: E
37. The suggestion that a person could gain from having an opposing lateralisation to most of the population.
Answer: H
Key words: person could gain, opposing lateralisation
Explanation: Paragraph H: “when it comes to hand-to-hand fighting, left-handers may have the advantage over the right-handed majority.” Left-handers gaining an advantage matches the statement.
left-handers may have the advantage = a person could gain from opposing lateralisation.
Answer: H
38. Reference to the large amount of knowledge of animal lateralisation that has accumulated.
Answer: B
Key words: large amount of knowledge, accumulated
Explanation: Paragraph B: “since then, researchers have built up an impressive catalogue of animal lateralisation.” “Impressive catalogue built up” = a large amount of accumulated knowledge.
built up an impressive catalogue = large amount of knowledge accumulated.
Answer: B
39. Research findings that were among the first to contradict a previous belief.
Answer: B
Key words: first, contradict a previous belief
Explanation: Paragraph B: “For many years it was assumed that lateralisation was a uniquely human trait, but this notion rapidly fell apart …” Rogers’ 1970s chick findings were among the first to overturn that belief.
notion rapidly fell apart = contradicted a previous belief.
Answer: B
40. A suggestion that lateralisation would seem to disadvantage animals.
Answer: A
Key words: disadvantage, seem to endanger
Explanation: Paragraph A: “a toad fails to escape from a snake … because its right eye is worse at spotting danger … So why would animals evolve a characteristic that seems to endanger them?” This presents lateralisation as an apparent disadvantage.
seems to endanger them = would seem to disadvantage animals.
Answer: A
| Answer Key (Quick Reference) | |||
|---|---|---|---|
| Q | Answer | Q | Answer |
| 27 | D | 34 | food |
| 28 | C | 35 | predator |
| 29 | E | 36 | E |
| 30 | B | 37 | H |
| 31 | environmental | 38 | B |
| 32 | light | 39 | B |
| 33 | multitasking | 40 | A |
Cambridge IELTS 1-21 Reading test solutions
Cambridge IELTS Reading KEYWORDS Table
