🗣️ Broca's aphasia
Damage: Broca's area, frontal lobe
Speech: slow, effortful, broken
Understanding: mostly intact
Main problem: producing speech
Biological Explanation of Language Acquisition » Aphasia: Broca's and Wernicke's
What you'll learn this session
Study time: 30 minutes
Cambridge spec: 6.2.3, 6.2.4
- What aphasia is and what can cause it
- How Broca's aphasia and Wernicke's aphasia look and sound different
- How to spot each type from a short description of a patient
- Why these two patterns support the biological explanation of language
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Unlock This CourseWhat is aphasia?
Most of us speak and understand language without thinking about it. But what happens if the brain is damaged? Sometimes a person loses part of their language ability, even though their hearing and their mouth muscles still work. Psychologists can learn a lot about how the brain handles language from these cases.
Key terms:
- Aphasia: a language impairment caused by brain damage following a head injury, a stroke or an illness.
- Broca's aphasia: aphasia where speech is slow and broken, but understanding is mostly fine.
- Wernicke's aphasia: aphasia where speech is fluent but makes little sense, and understanding is poor.
What can cause aphasia?
The spec names three causes. A person gets aphasia when the brain is damaged, usually after they have already learned to speak.
🤕 Head injury
A hard blow to the head, for example in a car crash or a bad fall, can damage the language areas.
🧠 Stroke
A stroke cuts off the blood supply to part of the brain. The brain cells there are damaged.
🏥 Illness
Some illnesses can damage brain tissue too, such as an infection of the brain or a growth in it.
The biological explanation: a quick reminder
The biological explanation says language depends on specific parts of the brain. You already know the two main language areas. Broca's area is in the frontal lobe and is linked to producing speech. Wernicke's area is in the temporal lobe and is linked to understanding speech. Aphasia lets us test this idea. If damaging one small area changes one part of language, that area probably does that job.
Broca's aphasia
Broca's aphasia is caused by damage to Broca's area in the frontal lobe. The problem is with producing speech.
- Speech is slow, effortful and broken.
- The person usually gets the key words out but leaves out small words, so sentences are short and choppy.
- Understanding is mostly intact. The person knows what you said to them.
- The person often knows that their speech is wrong, which can be very frustrating.
Example patient
A man had a stroke. When his daughter asks how he is, he says slowly, with long pauses: "Walk... dog... park... yesterday." He then nods when she says, "So you took the dog out?" He understands her perfectly, but he cannot put his own sentences together. This points to Broca's aphasia.
Wernicke's aphasia
Wernicke's aphasia is caused by damage to Wernicke's area in the temporal lobe. The problem is with understanding language, and with choosing the right words.
- Speech is fluent. It comes out easily, at a normal speed, with normal rhythm.
- But it is meaningless. The person may use the wrong words or even made-up words, so it does not make sense.
- Understanding is poor. The person struggles to follow what other people say.
- The person often does not realise that their speech makes no sense.
Example patient
A woman was hurt in a head injury. Asked what she had for breakfast, she replies quickly and cheerfully: "Well, the table went over to the blender and I flipped the garden so it was fine." She does not seem to notice that this makes no sense, and she cannot follow a simple instruction like "Please lift your hand". This points to Wernicke's aphasia.
Comparing the two types
👂 Wernicke's aphasia
Damage: Wernicke's area, temporal lobe
Speech: fluent but meaningless
Understanding: poor
Main problem: understanding speech
Why does this support the biological explanation?
The two types of aphasia look very different. Damage to different places causes different language problems. This is the key point.
- If language were spread evenly across the whole brain, damage to any part would cause the same kind of problem.
- Instead, damage to the frontal lobe harms speech production, and damage to the temporal lobe harms understanding.
- So specific brain areas seem to do specific language jobs. This is evidence that language has a biological basis.
Common mistakes
Common mistakes
- Mixing the types up. A tip: Broca's means Broken speech.
- Saying Wernicke's patients cannot speak. They speak a lot. It is the meaning that is missing.
- Saying Broca's patients cannot understand. Their understanding is mostly fine.
- Forgetting to link the evidence to the explanation. Always say that different damage gives different problems, so different areas have different jobs.
Exam-style question
A man has a stroke. Afterwards he speaks slowly and with great effort, using only a few words at a time. He understands what other people say to him.
(a) Name the type of aphasia the man most likely has. [1 mark]
(b) Describe one difference between this type of aphasia and Wernicke's aphasia. [2 marks]
(c) Explain how aphasia supports the biological explanation of language. [3 marks]
Model answer
(a) Broca's aphasia (1).
(b) In Broca's aphasia speech is slow and broken, but in Wernicke's aphasia speech is fluent (1). Also, understanding is mostly fine in Broca's aphasia, but it is poor in Wernicke's aphasia (1).
(c) Damage to different brain areas leads to different language problems (1). Damage to Broca's area in the frontal lobe harms speech production, while damage to Wernicke's area in the temporal lobe harms understanding (1). This suggests that specific brain areas control specific parts of language, so language has a biological basis (1).
Exam tip
In part (b), name both types and write about the same feature for each, such as speech. A one-sided answer will not get both marks.