Perception and the senses are two of my favorite subjects to
teach. There are so many experiments and
demonstrations that can be used to explore how we receive and process
information from the outside world.
I started the discussion with the nuns with an explanation of how we have receptors that are specialized to respond to different types of energy (e.g., light, chemicals, mechanical movement). To compare the reaction time to light, sound and touch, the nuns did the ruler drop experiment. First, they hypothesized which sense would have the fastest reaction time. Most of them thought that vision would be fastest. Then the nuns got into pairs to test their hypothesis.
One nun in each pair
was the experimenter and the other was the test subject. To test visual reaction time, the
experimenter would drop the ruler and the subject had to catch it with her
thumb and first finger. The number of
centimeters the ruler dropped was recorded.
To test auditory reaction time, the test subject closed her eyes and the
experiment would drop the ruler and say “drop” at the same time. Again, the distance the ruler fell was
recorded. For touch, the test subject
closed her eyes and this time the experimenter lightly tapped on the foot of
the test subject when the ruler was dropped.
Each sense was tested three times and the roles of
experimenter and test subject were reversed.
Everyone then averaged their data to get a value for each sense. The nuns then wrote their averaged reaction
time numbers on the whiteboard and a grand average for each sense was
calculated.
It turned out that vision did result in the fastest reaction
time. I asked the nuns how confident
they were of their data and how we could have made the experiment better. Ideas the nuns came up with included:
Better
experimental set up such as making sure that the ruler was in the same place
every time it was dropped.
More
trials:drop the ruler more times for
each sense.
More
people: test more than just the nuns in the class.
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