Taste Illusion

Lesson Plan 21 Taste Illusion

Students taste and record the ﬂavour of two types of cordial, one pink and one green. The responses are tallied before the astonishing secret is revealed. Apart from green food colouring, the samples are identical and taste exactly the same. The surprising revelation about our preconceptions of ﬂavours may even help some students reassess their attitudes to a nemesis vegetable.

NOTE: Please check your students’ dietary restrictions prior to this activity

Duration: 45–60 minutes Year Level: Primary, secondary Topics: The senses, food and nutrition, health, percentages (maths) Preparation: 5 minutes

Overview

Whole class Introduce the lesson. Distribute cordial samples and response forms.

Individual Students taste their samples and record the ﬂavour.

Whole class Tally the ﬂavours each student recorded on the whiteboard.

Optional Students calculate the percentage of students that tasted each of the ﬂavours recorded.

Whole class Discuss the results.

Materials • Raspberry or strawberry cordial • Water • Green food colour • 60 small plastic cups • 1 two-litre (2L) jug • 1 one-litre (1L) jug • Response forms (page 4) • Serving trays

Preparation Photocopy sufﬁcient quantities of the response forms for the whole class. Prepare two litres of weak cordial (i.e., slightly less more diluted than the manufacturer’s recommended concentration) and stir thoroughly. Pour half the mixture into the second jug. Add a few drops of green food colour to one of the jugs until the mixture turns slightly green to give the appearance of lime ﬂavouring.

Lesson Plan 21 – Taste Illusion | Page 1

Science concepts The sense of taste is susceptible to illusions based on preconceptions about the colour and ﬂavour of foods.

Positive attitudes

Develop an appreciation of the interconnected nature of the human senses. Develop an appreciation of the impact of preconceived ideas about food on ﬂavour.

Procedure

Discuss the lesson Tell the class that you have two kinds of cordial (don’t use the word ﬂavours here) they will taste to compare and rate against their favourite beverages. Ask the students not to discuss their responses until all the forms have been returned to you. They do not need to record their names on the forms.

Conduct the taste test Distribute the response forms and cordial samples. Collect the response forms.

Tally and discuss the results Before discussing the results, you may need to prove that food colouring does not change the flavour of cordial. One method is to ask several students to taste plain water with a drop of food colour added and report the flavour. Alternatively, blindfold students and ask them to identify which of two glasses of water contains green food colouring. (You’ll need to repeat this several times for several students to incorrectly identify the plain.) Optional: calculate the percentage of students that thought the green sample was lime flavoured cordial. Were they surprised to learn that the green cordial was not lime flavoured but, in fact, identical to the pink cordial? Why did so many people taste lime when the cordial is actually strawberry or raspberry flavoured? Ask students to think about their nemesis vegetable (e.g., brussels sprouts and broccoli) and reconsider the possibility that their mind could be playing tricks on them. Perhaps they do not dislike this vegetable as much as the believe?

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1 Prepare two litres of cordial slightly weaker than the manufacturer’s recommended concentration. Pour half the cordial into a second jug and add a few drops green food colour to give the appearance of being lime ﬂavoured.

2 Pour approximately 15ml of cordial into small plastic sample cups. (One green and one normal sample for each student.)

3 Distribute the cups and response forms. Ask the students to taste each cup and record the ﬂavour.

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Write down the flavour of the two cordial Write down the flavour of the two cordial samples you were asked to taste. samples you were asked to taste.

Pink cordial = ______Pink cordial = ______

Green cordial = ______Green cordial = ______

Cordial Flavour Cordial Flavour

Write down the flavour of the two cordial Write down the flavour of the two cordial samples you were asked to taste. samples you were asked to taste.

Pink cordial = ______Pink cordial = ______

Green cordial = ______Green cordial = ______

Cordial Flavour Cordial Flavour

Write down the flavour of the two cordial Write down the flavour of the two cordial samples you were asked to taste. samples you were asked to taste.

Pink cordial = ______Pink cordial = ______

Green cordial = ______Green cordial = ______

Cordial Flavour Cordial Flavour

Write down the flavour of the two cordial Write down the flavour of the two cordial samples you were asked to taste. samples you were asked to taste.

Pink cordial = ______Pink cordial = ______

Green cordial = ______Green cordial = ______

Lesson Plan 21 – Taste Illusion | Page 4