8/23/16 Show feat. Matt Grobis on the emergent properties of groups

Schools of fish, like these and the minnows Matt Grobis studies, display behaviors as a group that they cannot replicate as individuals. Image from: Octavio Aburto at Scripps School of Oceanography, UCSD.

Matt Grobis

This week on These Vibes, Stevie interviewed Matt Grobis,  graduate researcher in the department of Ecology and Evolutionary Biology here at Princeton. Matt is also director and co-founder of Princeton Open Labs which organizes science outreach talks and activities for local schools, and writes for a couple blogs: Highwire Earth, an interdisciplinary blog on sustainable development in our changing and growing society where he’s managing editor and co-founder (Matt and Julio Herrera Estrada, the fellow founder of Highwire, came on TVR2C previously for a short segment where they discussed the site) and The Headbanging Behaviorist, which mixes science, activism, and music (so he fits right in here at These Vibes Are Too Cosmic).

We began our discussion with some of the things animals can do together that they cannot especially do alone. Examples of these are migration and predator evasion. For example, the fish shiners prefer to stay in shadows because that will protect them from predators lurking above, but – as Matt discusses in the show – they can’t see the gradients in light well, and thus have difficulty find the shadows unless they’re in a group. Individuals could measure the light level where they were and would change their speed to match it, but they couldn’t actively move to darker areas, so they’re much more likely to be snapped up by a predator. (Here’s the study that found this.)
 Grobis conducts his research both in a lab with actual schools of minnows in a tank and cameras recording their movement (he even has some fake predator concoction to scare the fish), as well as “theoretically” – read: with computer models (like this interesting

School of minnows, from wikicommons.

agent-based model he mentions in the show). Matt’s lab research measures what’s called the “startle.” This is the wave that passes through a school of minnows, for example, when they are, well, startled. In the show Matt also calls this a “cascade.” (Here’s the original paper on startles , also featured in Cell, that Matt’s research is building on.) Matt is seeing if the mechanisms by which the cascade spreads hold up when there’s elevated perception of risk in the environment. Preliminary results indicate that under increased perception of risk, startles might spread a bit differently!

As an example of interesting group behavior, Matt later discussed a specific study (“Uninformed individuals promote democratic consensus in animal groups”, Couzin et al. 2011) that was done with schools of fish. In this experiment the group cannot break apart, but part of the group wants to go towards a blue stimulus and another part really wants to go towards yellow – the behavior that emerges is interesting and seems very relevant to human situations we get in to all the time. (Choosing a dinner place in a big group, anyone?) You can take a look at the study here, and read a blog entry in Headbanging Behaviorist where Matt discusses what happened behind the scenes (a kind of “making of” of the study – this will  be much more accessible than reading the paper itself).
After the interview, Matt noted that “one of the reasons Couzin et al. 2011 is so cool is that they started with the models and found the results in that theoretical universe on their computers. Then, they really hammered it home by showing it’s true in the real world too. So it’s more a good example of the power of combining theoretical models with experiments.” How cool!
In the show we received some excellent listener questions. One listener asked whether Matt’s research on the behaviors of groups could be used to control humans. From this we determined that maybe “control” was a bit strong, but that perhaps this group research could help us better guide traffic, be it in a street or a busy transit hub like an airport. Remember, “ants don’t have traffic jams.”
(In this part Matt mentioned research on autonomous robots that his adviser Iain Couzin is working on. It’s sponsored by the Office of Naval Research and is shared with Mechanical and Aerospace Engineering Professor Naomi Leonard.)
If you live in the Princeton area, and especially if you have school-aged children, please check out Matt Grobis’s side project Open Labs!
The great minnow.

playlist 082316

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