What sleep research can and can't tell us about animal dreams. Rats seem to replay a maze, pigeons may dream about flying, dolphins sleep with half a brain, and two octopuses behave as if they're dreaming. The catch is that we can never actually see inside another creature's dream.
The table (1-5) comes from paragraphs B to D in order. The TRUE / FALSE / NOT GIVEN block (6-13) carries on from E to the end, one or two statements per paragraph.
Table completion (ONE WORD ONLY)
Questions 1-5
How to attack this block: The table works animal by animal, so find each animal's paragraph and take one word from it. Question 3 is a fraction written as a word, and question 5 is a describing word, not a noun. Check the word class the table cell needs before you copy anything.
Question 1
Answer: ratsParagraph B
Which animal showed the same brain patterns awake and asleep?
researchers compared the brain patterns of rats running through a maze when awake with their brain patterns during REM sleep. They found the patterns were very similar
Question says → Passage says
similar brain patternsthe patterns were very similar
when active and sleepingrunning through a maze when awake… during REM sleep
indicative of dreamingconcluded that the sleeping rats were dreaming
Why: The table's first column names the animal studied, and paragraph B's study is on rats. Keep the plural, since the passage talks about rats in general, and check your spelling.
The trap: 'Mammals' appears in the sentence before, but that's the group, not the animal the researchers tested. The table rows each name a specific animal: pigeons, whales and dolphins, so this one is 'rats'.
Question 2
Answer: visualParagraph C, last sentence
What kind of input do the active parts of a sleeping pigeon's brain deal with?
REM sleep activity was high in brain regions involved in processing visual information, especially images related to physical activities such as flying
Question says → Passage says
parts of the brain that deal withbrain regions involved in processing
___ inputvisual information
Why: 'Deal with' matches 'involved in processing', and 'input' replaces 'information'. The gap sits before a noun, so it needs an adjective: 'visual'.
The trap: 'Images' or 'flying' are nearby, but neither fits 'deal with ___ input' grammatically, and 'flying' is already used in the Comment column.
Question 3
Answer: halfParagraph D, fourth sentence
How much of their brain do whales and dolphins keep awake while sleeping?
which do not shut down their entire brain when they sleep, but only half of it, keeping the rest awake
Question says → Passage says
still have ___ their brain awakeonly half of it, keeping the rest awake
Why: They shut down half and keep 'the rest' awake, and the rest of a half is the other half. The gap needs a word that works before 'their brain', and 'half their brain' is natural English. Write it as a word, not '1/2'.
The trap: 'Entire' is in the same sentence, but it's what they do NOT shut down. Read the 'not… but only' structure carefully.
Question 4
Answer: temperatureParagraph D, last sentence
What would REM sleep make whales and dolphins more sensitive to?
It's thought that they don't experience REM sleep because during REM sleep animals are more vulnerable to extremes of temperature.
Question says → Passage says
do not experience REM sleepthey don't experience REM sleep
affect their sensitivity tomore vulnerable to
Why: 'More vulnerable to' is the passage's way of saying 'more sensitive to'. What they'd be vulnerable to is 'extremes of temperature', and one word means 'temperature'.
The trap: 'Extremes' is the first word after 'vulnerable to', but extremes of what? On its own it makes no sense in the table. The meaningful noun is 'temperature'.
Question 5
Answer: vividParagraph D, fifth sentence
What are whale and dolphin dreams probably not?
They also show no sign of REM sleep, suggesting that they may only experience non-REM dreams, which are less vivid.
Question says → Passage says
probablysuggesting that they may
not veryless
Why: Non-REM dreams are 'less vivid', so their dreams are 'not very vivid'. The gap follows 'not very', so it needs an adjective.
The trap: 'Complex' appears in the next sentence ('complex inner lives'), but that's what we imagine about their lives, not a description of their dreams.
TRUE / FALSE / NOT GIVEN
Questions 6-13
How to attack this block: Eight statements and three NOT GIVENs. The FALSE answers all hinge on swapping details: which octopus did what, 'never' against 'soon', 'we know' against 'we don't know'. Read each statement's subject carefully before hunting for evidence.
Question 6
Answer: TRUEParagraph E, second and third sentences
Does dreaming about past events help us turn them into long-lasting memories?
It is believed that when events are replayed in dreams, this helps to integrate memories into longer-term storage.
Question says → Passage says
dreaming about past experiencesevents are replayed in dreams
create lasting memoriesintegrate memories into longer-term storage
Why: Replaying events in dreams is dreaming about past experiences, and putting memories into 'longer-term storage' is making them last. The statement says exactly what this sentence says, so TRUE.
The trap: Some people hesitate because the passage says 'it is believed'. The statement doesn't claim certainty either, and the passage presents this as the growing evidence, so it's still TRUE.
Question 7
Answer: FALSEParagraph F, last sentence
Can we now tell what a dog is dreaming about?
We are quick to interpret the twitching limbs and quiet barks of sleeping dogs, but the truth is that we don't know if there is an internal experience of chasing rabbits
Question says → Passage says
it is now possible to tellthe truth is that we don't know
what type of dream a dog is havingan internal experience of chasing rabbits
Why: The passage says the opposite of the statement: we guess at dogs' dreams but 'we don't know' what they experience. 'Possible to tell' contradicts 'don't know', so FALSE.
The trap: 'We are quick to interpret' sounds like we can read their dreams. The sentence goes on to say those interpretations are guesses, and that 'but' is what makes it FALSE rather than TRUE.
Question 8
Answer: NOT GIVENParagraph G
Did Scheel's documentary shape other research on octopus sleep?
In 2019, while making a documentary, David Scheel of Alaska Pacific University in the USA housed an octopus named Heidi in a tank in his living room.
Question says → Passage says
David Scheel's documentarywhile making a documentary
Why: The documentary is only mentioned as the reason Heidi was in Scheel's living room. Nothing is said about whether it influenced anyone else's research, so NOT GIVEN.
The trap: Paragraph H mentions a second octopus report straight after, which can look like a follow-up study. The passage never links it to the documentary.
Question 9
Answer: FALSEParagraph H, second sentence
Did Costello act as if he was hunting in his sleep?
squirted ink as though he were being attacked by a predator
Question says → Passage says
reacted as if it was huntingas though he were being attacked by a predator
Why: Costello behaved like prey, not a hunter: he made himself look bigger and squirted ink as though a predator was attacking him. Being attacked is the opposite of hunting, so FALSE.
The trap: Heidi, the other octopus in paragraph G, looked as if she was chasing a crab. Mix up the two names and you'll say TRUE.
Question 10
Answer: TRUEParagraph H, last two sentences
Does Scheel think octopus dreams need more study?
The nightmare study is intriguing, says Scheel, but is only based on one animal. He argues that as well as outward behaviour, brain imaging is needed
Question says → Passage says
Scheel believessays Scheel / He argues
more research should be carried outonly based on one animal… brain imaging is needed
Why: Scheel says one animal isn't enough and that brain imaging 'is needed' to show octopuses really replay their day in dreams. Saying more evidence is needed is saying more research should be done, so TRUE.
The trap: The passage never uses the words 'more research', so NOT GIVEN can feel safe. But 'only based on one animal' plus 'is needed' is a clear call for further study.
Question 11
Answer: FALSEParagraph I, first two sentences
Will we soon be able to share other people's dreams?
The trouble is that we will never be able to experience any animal's dreams. That goes for other humans' dreams too.
Question says → Passage says
may soon be able to sharewill never be able to experience
the dreams of other human beingsother humans' dreams
Why: 'Never' directly contradicts 'soon', and 'that goes for other humans' dreams too' brings humans into it. FALSE.
The trap: NOT GIVEN is the usual wrong answer because the main topic is animals. The second sentence extends the 'never' to humans, so the passage does answer this.
Question 12
Answer: NOT GIVENParagraph I, last two sentences
Could hearing matter in some animals' dreams?
vision is the dominant sense for many humans, and so our dreams are heavily visual too. Dogs primarily navigate the world using smell while spiders rely much more on vibrations.
Question says → Passage says
important part of the dreamsour dreams are heavily visual
Why: The passage links senses to dreams and names three: vision for humans, smell for dogs, vibrations for spiders. Hearing is never mentioned for any animal, so NOT GIVEN.
The trap: Vibrations feel close to sound, and dogs' 'quiet barks' appear in paragraph F. But neither is hearing as a dream sense, and the passage only links vision directly to dreams.
Question 13
Answer: NOT GIVENParagraph J
Has interest in why humans dream grown a lot recently?
it is possible that better understanding of these purposes might shed light on the true purpose of our own dreams
Question says → Passage says
the reasons why humans dreamthe true purpose of our own dreams
Why: The last paragraph says animal research might help explain the purpose of human dreams. It says nothing about how much interest there is in that question, now or before, so NOT GIVEN.
The trap: The topic matches perfectly, which makes TRUE tempting. Look for the idea of 'increased greatly in recent times': there's no comparison over time anywhere.
There are two octopuses. Heidi (G) looked as if she was chasing a crab. Costello (H) acted as if he was being attacked. The statement gives Costello the hunter's role, so FALSE.
Paragraph I says we will never experience another animal's dreams, and that the same goes for other humans. 'Soon' contradicts 'never', so FALSE, not NOT GIVEN.
The passage names vision for humans, smell for dogs and vibrations for spiders. Hearing is never mentioned, so NOT GIVEN.
Words from this passage worth keeping
alternate(A)
happen one after the other, again and again
vivid(A)
very clear and detailed, almost like real life
intriguingly(C)
in a way that is interesting because it is unexpected
universal(D)
true of or found in every member of a group
vulnerable to(D)
easily harmed or affected by something
integrate(E)
combine one thing into another so they work together
on their own terms(I)
in the way that suits them, not the way that suits us
shed light on(J)
help to explain something
Sit this test on Langujet, then come back
The full Cambridge 21 Test 2 reading paper: all three passages, 60 minutes, marked the second you finish with a review of every answer. Already done it? Take it again and see if the same traps still get you.
Cambridge IELTS 21, Test 2, Reading Passage 1. The passage and questions belong to Cambridge University Press and are not reproduced here. We quote short extracts only as evidence for our own commentary, and the answers are published for self-marking. Get the book for the full text, or sit the test on Langujet.
FAQ
Do animals dream?: quick answers
"Do animals dream?" is Reading Passage 1 of Cambridge IELTS 21, Test 2. It covers questions 1-13 (13 marks).
Questions 1-5: Table completion and questions 6-13: TRUE / FALSE / NOT GIVEN.
2 TRUE, 3 FALSE and 3 NOT GIVEN.
Our review highlights questions 9, 11 and 12. Each one is explained in "Questions worth a second look" above.
