Posted 4/9/07
This is a fantastic experiment for the classroom. In the video clip, the ears hear one sound and the eyes see (or rather, lip read) another. The result is the perception of a third sound. This is known as the McGurk Effect and you can use it to freak out your students (most teachers I know like to do that every now and then). Dr John Medina, author of Brain Rules explains all in this video.
  • Language level: Intermediate (B1) +
  • Learner type: Teens; Adults; CLIL
  • Time: 50 minutes
  • Activity: Reading; Listening; Speaking
  • Topic: Psychology & behaviour; Linguistics
  • Language:  Minimal pairs; Nouns that end in -ion
  • Materials: Video; Worksheet
An auditory illusion pdf [downloaded 2343 times]

Lesson plan outline

  1. Write the following on the board:
  2. Ba-ba
  3. Drill the three sounds and make sure your students can distinguish between them.
  4. Tell students that in phonetics, the three sounds are represented with the following symbols shown on the right. Ask students to consider how the sounds are produced and ask them to consider what they have in common and how they differ.
  5. Copy the gapped text below onto the board. Ask students to copy it into their notebooks and fill in the missing words – they are all parts of the body. Allow students to work together for this if they desire.
  6. /b/, /d/ and /g/ are examples of plosives. That means that they are produced by stopping airflow in the (i) ________________, building up pressure and then releasing.

    /b/ is produced when the (ii) ________________ meet and stop airflow.

    /d/ is produced when the tip of the (iii) ________________ meets the part of the mouth just behind the upper (iv) ________________ (the alveolar).

    /g/ is produced when the back of the (v) ________________ meets the soft part at the back of the (vi) ________________ (the soft palate).

    All three sounds are voiced. That means that the vocal chords vibrate while the shapes are made in the (vii) ________________.

  7. Go over the answers:
  8. i. Mouth
    ii. Lips
    iii. Tongue
    iv. Teeth
    v. Tongue
    vi. Throat
    vii. Mouth

  9. Tell students that you are going to play a short video clip in which a man produces a sound. Label all students as either A or B.
    • Tell A students that you want them to close their eyes and listen only.
    • Tell B students that you want them to watch and listen to the clip.
  10. Tell students that their task is to write down the spoken sound that they hear in the clip. Make it clear that they should ignore all background noise.

    * Students who listen only will usually hear ba-ba.
    * Students who listen and watch will usually hear da-da.
  11. Play the clip and then let students compare what they heard.
  12. Let students change roles: those who listened with their eyes closed should now listen and watch at the same time. Those who listened and watched should close their eyes.
  13. Again, allow students to compare what they heard.
  14. Put students into pairs or small groups and ask them to consider how the discrepancy can be explained. If anyone thinks they have the answer, invite them to share it with the rest of the class.
  15. Ask students if they know what an optical illusion is. Ask for some examples. Tell them that this is an example of an auditory illusion called the McGurk effect.
  16. Ask students if they can tell you what the McGurk effect demonstrates (the answer will be in the text in the worksheet).
  17. Give out the McGurk Effect worksheet (included in the PDF download) and ask students to complete it (answer also included in PDF).

Posted 4/9/07

4 Responses to An auditory illusion

  1. James Wylie says:

    When I did this myself, I ‘perceived’ exactly the differences mentioned above. Did it for five minutes in an FCE class yesterday, and, whilst it was interesting, and some perceived differences, there were several puzzled faces, with students saying they got any combination of the sounds, including /p/. Does perceiving something that’s not the norm above imply anything about the perceiver?

  2. Jamie Keddie says:

    Hi James

    I really don’t know the answer to this. I know that not everyone will perceive the sounds as the illusion intends but not much more.

    One thing that I found is that when you show the clip, you have to make sure that the image is clear. I played the clip once and it was a bit too dark to see the mouth movements clearly. As a result, less people ‘got’ the illusion.


  3. Hi Jamie!

    As I had mentioned to you, I prepared an activity / lesson based on this video lesson. And I shared the activity on my blog – as you’ve seen. Here’s the link:

    Thanks for the inspiration!!!!


  4. Jamie Keddie says:

    Thank you Cecilia
    I love what you did. Thank you for sharing the power point.
    I hope the activity went well
    Ba ba!
    Jamie :)