Saturday, January 22, 2011

The Great Apple Experiment

My son's Scout troop has taken me up on my offer to help them get their science badges. To do this, we're going to run the Great Apple Experiment with the whole troop.  Basically, Nikki Owen made a claim that cutting an apple in half and talking nicely to one half and meanly to the other half makes the nice one rot more slowly than the bad one.  Rebecca Watson ran an experiment on this claim and invited everyone to write their results on a Facebook page.

We have 22 Scouts in the troop and I'm going to get them all to run the apple experiment.  We'll start by discussing bias, blinding and controls. We'll then cut up the apples, place them into marked containers, and have the scouts talk to them every day until the following week's meeting.  We'll then have all the Scouts assess all of the apple slices and collect the results.

I don't have much time to develop and get feedback on the protocol for the experiment, so I thought I'd post it here and get feedback.

Protocol (thanks to PZ Myers for his suggestions):
  • Discard any apples that are obviously bruised or nicked
  • Wash the apples and slicer before beginning
  • Slice apples into 8 pieces (Rebecca suggests 2 pieces but I don't have a budget for that many apples considering the other things I want to do)
  • Apple slices are placed into clear containers which are marked by unique numbers
  • Each Scout gets 6 apple slices (Love, Hate, Neutral, Untouched Control, Known Preservative, Open Air) chosen at random from the available containers
  • For Known Preservative, we'll coat the apple slices with lemon juice
  • For Open Air the slice will be kept in a container with no lid.  We will use paper towel on top held on by an elastic band to prevent any insects from entering.
  • Each container will have a window into which we'll slide a label saying "Love", "Hate" etc.  This is to help prevent mistakes while the Scouts have the apples home during the week.
  • The container numbers are recorded indicating which number goes to which Scout and what the label on that container reads (Love, Hate, etc).
  • Each container will be sealed with a lid that won't be removed for the remainder of the experiment
  • The Scouts take the containers home.
  • Each day, they will take the Love container to another room, say nice things to it and return it.
  • They then take the Hate container to another room, say bad things to it and return it
  • They then take the Neutral container to another room, say neutral things to it and return it.
  • All other containers remain untouched for the week
  • At the end of the week, the Scouts will bring the containers to the meeting
  • Each Scout will rate his own 6 slices (knowing which is which) on a scale from 0 (not rotted at all) to 10 (very rotten). We'll provide photos of each level for reference.
  • Each Scout will then remove the labels Love, Hate etc. leaving only the numbers on the containers and place them in a line on a table
  • A Scout leader will re-arrange all containers randomly
  • Each Scout will rank each apple (skipping their own which they've already ranked)
  • Scouts cannot show their rankings to other Scouts or discuss the experiment with other Scouts until the experiment is complete.
After the results are collected, we will analyze the results:
  • Each slice will be grouped by category - Love, Hate, Neutral, etc excluding the Scout's assessment of his/her own slices.
  • In each category, the ratings will be averaged and standard deviation calculated
  • Each Scout's assessment of his or her own slices will be compared to the averages to determine if the Scouts exhibited bias in assessing their own slices without blinding
  • All results will be published on the Internet with photos and videos
PZ Myers suggested that the Scouts may try to write up their results for an article in Skeptic Magazine which we'll look at for a follow-up meeting.

If you have any comments or suggestions on this protocol, please e-mail me at or post them as comments to this post.


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