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Pavlovian conditioning in plantsFeatured science projectScience project video

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Complexity level:
8
Project cost ($):
20
Time required:
7 days to prepare, 2 hours for the science fair project experiment
Material availability:
Purchased at a plant nursery
Safety concerns:

Basic safety requirements

Abstract

This science fair project was performed to ascertain if Pavlovian conditioning works in plants. The The science project experiment involved the Mimosa Pudica plant.

Hypothesis

The Mimosa Pudica plant will not respond to Pavlovian conditioning.

Background

Mimosa Pudica

The Mimosa pudica is a plant which has leaves that will droop and close shut if they are stimulated by touch, wind or by shaking. The leaves will normally re-open a few minutes after the stimulation has ceased. This plant will also normally close its leaves at night or in the dark and open them in daytime.

The movements of the leaves are called seismonastic movements. When the Mimosa pudica plant is given stimulus by touch, the cells in certain parts of the leaves will lose their turgor pressure. This pressure is the force of the water within the plant cells, against the walls of the cell. The stimuli will trigger the release of chemicals that will force the water in the cells to escape. This will make some parts of the leaves to lose pressure and the leaf petiole will close.

Pavlovian conditioning

Pavlovian conditioning occurs when a significant stimulus (like feeding) which has an unconditional response (like salivating) is preceded by a conditional stimulus (like the ringing of a bell). When this is repeated over and over again, associated learning occurs and the two events become connected in the memory of the test subject. The next time the conditional stimulus (ringing the bell) occurs, the unconditional response (salivating) will happen even if there is no significant stimulus (feeding or food) present.

Scientific Terms

Mimosa pudica, stimulated, seismonastic movements, turgor pressure

Materials

The materials required for the science fair project:
- 20 Mimosa pudica plants growing in a plastic basin
- An air conditioned room with dimmer light
- A clock
- An assistant

Procedure

1. For this science fair project, the independent variable is the change in room temperature and dimming of lights. The dependent variable is how the Mimosa pudica plant reacts - whether it closes its leaves or not. The constants (control variables) are the number of plants used, the number of days the plants have been given the conditional stimulus of lowering the room temperature and the brightness of the room.

2. Twenty Mimosa pudica plants are grown in a plastic basin. They are kept and grown indoors in a room with windows so that the plants receive sufficient sunlight. The plants are watered daily and kept healthy.

3. Once the plants have grown to about 200mm in length, the testing begins. For the next 6 days, the plants are kept in a well lit room for 12 hours and kept in darkness for the next 12 hours. During the transformation from  the bright room to  the dark one, the temperature of the air conditioner is reduced from 25 °C to 16 °C. The lighting in the room is also gradually reduced from bright to dark in 15 minutes. The leaves of the Mimosa pudica plants will also close in the dark.

4. On the seventh day, the temperature of the room is reduced to 16°C after 12 hours of brightness, but the room is not dimmed. It is observed whether  the leaves of the Mimosa pudica plants will remain open or close. The observation is recorded in the table given below.

Observation

The results showed that all 20 Mimosa pudica plants did not shut their leaves when only the temperature of the room was reduced, without the light being dimmed.

Plant number

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

day 1

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

day 2

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

day 3

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

day 4

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

day 5

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

day 6

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

day 7 (light on)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O – leaves remain open, C- leaves closed

Conclusion

The Mimosa Pudica plant will not respond to  Pavlovian conditioning. has been  proven to be true.

Pavlovian conditioning will require the use of the brain’s memory to recall and associate the 2 events of unconditional stimulus and conditional stimulus. Plants do not have a brain nor memory. Therefore they are not unable to demonstrate a Pavlovian response.

Also consider

To improve the reliability and accuracy of our results, a larger sample of plants should be used.

This science fair project may be repeated, this time, by using animals like dogs or cats and food as the conditional stimulus.

Modify the science project experiment, exposing the plants to the conditional and unconditional stimulus for a longer period of time (eg. 3 months) in order to establish if the plants perhaps take a longer period to develop  Pavlovian conditioning.

References

Mimosa pudica- http://en.wikipedia.org/wiki/Mimosa_pudica

Classical conditioning - http://en.wikipedia.org/wiki/Classical_conditioning

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