Strange to be introducing a new project on my conclusion post, but it’s a cool one!
While waiting for pea plant project parts to arrive, I revisited another project that Monica Gagliano had done with the Mimosa pudica: https://youtu.be/Xm5i53eiMkU?t=2m45s. For those of you too impatient to watch a video (like me!) the Mimosa pudica is a plant that is
“known for its leaf-folding behaviour in response to physical disturbance.” Basically, its leaves fold up and/or its stem falls when it receives a strong enough stimulus:
(For excellent background reading on the Mimosa pudica, go here.) Basically, the new kid on the block is shy, sensitive, bashful. But with some training, could they become less so? Can they habituate to a certain stimulus?
“Habitu-they can!” is what Monica Gagliano et al. said in their paper, “Experience teaches plants to learn faster and forget slower in environments where it matters.” She dropped some 56 mimosas 60x in a row, 7x a day, to see if they’d stop closing their leaves after a while, when they ‘learned’ the stimulus wasn’t harmful. She measured leaves before and after as the measurement of response.
Sofie, a high school intern with us, built this plant dropping machine and ran some pilot tests:
Unfortunately, we got banned from the closet to drop the plants. Last weekend, I dropped 12 plants in my apartment, 9 in the experimental group and 3 in the control group. 60 times, 7 times a day. 3,783 is the number of times I would take a plant and drop it.
- Drop control plants once, 8 hours apart.
- Drop experimental plants 60x at time 0, after 10 minutes, after 1 hour, after 2 hours, after 4 hours, and after 6 hours.
- Then give them a new stimulus: in our case …
Yes. We shake the plant. The idea behind this is that the leaves will close right up again because it’s a new stimulus.
- Finally, drop it 60 more times after 10 minutes (once the leaves have opened up). Since it’s a familiar stimulus that they have hopefully learned is not dangerous, we’d expect plants to open up again.
But as always, we need to compare it to a control. Putting all the data together, here is what we find:
Want to see Monica Gagliano’s results to compare? Of course you do.
There are several important differences between my data and Monica Gagliano’s data.
- Her control plants closed a lot more in that first drop.
- She noticed learning during the first 60 drops, meaning the leaves started opening up in the middle of the 5-10 minute period when they were being dropped. My plant students, not so smart. They peaked learning at 2 hours and then seemed to forget most of it quite quickly. Hmm… not so much different from my human students…
- Her plants showed a strong response to the dis-habituation stimulus. They really didn’t like Swift’s suggestion to Shake It Off. My plants seemed to treat being shaken the same as being dropped. (Monica Gagliano’s protocol was to put them on a 250rpm shaker for 5 seconds. 250 rpm:
Her data is statistically significant. Mine? To be determined….
Qualitatively, what I noticed was that the plants seemed to exhibit maximum learning at 2 hours. They seemed to habituate to the force of stimulus rather than what the stimulus was (explanation for similar response to dishabituation). Also, notice how high plants 1-3 are in my graph post dis-habituation (upper right corner of my graph)? That’s because I only dropped them once, instead of 60 times, much like the control. I should probably take that out for my poster, but I wanted to show you all.
Anyway, if the plant’s brain is in its roots, as Darwin proposed, who knew that dropping plants on their heads would help them learn?
I’ll leave it here, but I’d like to thanks some people for helping me carry out my projects. Couldn’t have done without them:
And of course, all the people at the BYB office: Zorica, who would take extra care for the plants and go out of her way to help us; Katie, who would always make space for me crowding her space at the 3D printer; John, for lending out his beloved tools; Caitlin, for being patient with my late blog posts; Will, for his awesome mustache; Sanja, for help with getting me reimbursed; Greg, for being captain of this fellowship experience!
So much more to share, and I’m still waiting on one more data result, but goodbye for now!