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That Time We Put Spiders in VR
That Time We Put Spiders in VR
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Субтитры (208)
0:00
Putting lab rats in a maze is a bit of a science cliche.
0:02
And for good reason! Scientists really do design
0:05
a lot of experiments that involve putting rats in mazes.
0:08
Watching how they handle being plopped in an obstacle course
0:10
reveals a lot about how they see, think, and navigate their surroundings.
0:14
It’s so illuminating that scientists
0:16
can’t seem to stop themselves from designing all sorts
0:19
of little escape rooms for their animal test subjects.
0:22
So here are five times scientists put animals in ridiculous situations
0:26
just to see what they would do.
0:28
[Intro music]
0:31
You’ve likely heard that bats use echolocation to help them navigate.
0:34
They can find food with ease and fly around with excellent obstacle avoidance.
0:38
All thanks to a fairly simple concept.
0:40
The bat makes a noise,
0:42
like a chirp or click,
0:43
and the sound waves bounce off the things in their environment,
0:46
such as any tasty insects hovering nearby.
0:48
The bat listens for the echo and uses that to locate the tasty insect.
0:53
And also any neighbors or predators that it doesn’t want to bump into.
0:56
It’s easy to imagine how this works
0:58
if there are only a few flying insects and one hungry bat.
1:02
But what about when there are tens of thousands of insects,
1:06
and hundreds of bats that are also all echolocating?
1:10
How do the bats keep all that sound information straight?
1:13
To figure it out, scientists added some infrastructure to a natural corridor
1:18
with a lot of bat traffic.
1:19
Between these bats’ roost and feeding grounds,
1:22
the researchers installed four panels
1:25
with artificial leaves that were attached to conveyor belts.
1:28
They tracked how these bats changed their flight speed
1:30
when the artificial leaves were either moved with the bats’ direction of flight or against it.
1:35
They discovered that the bats flew slower or faster
1:37
than they did in static surroundings,
1:40
and their speed change depended on the way the echo frequencies shifted.
1:44
This means that bats don’t just listen for the time delay
1:47
between their noise and an echo.
1:49
They also listen for Doppler shifts.
1:51
Doppler shift is a change in frequency
1:53
that occurs when a signal source and the observer are moving relative to each other.
1:57
When the thing that makes the sound moves towards you,
2:00
the sound is pitched higher as the sound waves get squeezed together.
2:04
Then as it moves away, the pitch is lower
2:07
because the sound waves stretch out as they travel to you.
2:11
Like how the siren of an ambulance changes pitch as it speeds past you.
2:14
So the idea is that if the leaves move in the same direction as the bats’ flight,
2:18
their echo would be pitched down.
2:20
That could make the bats think they’re flying slower than they thought they were,
2:24
and they might speed up to compensate for that.
2:26
And vice versa, if the leaves move against the bats’ flight direction,
2:29
their echo would pitch up, and the bats might think they’re flying too fast!
2:33
The researchers want a bigger data set before drawing too many conclusions.
2:37
But they believe this obstacle course could provide evidence
2:39
that bats gauge speed based on acoustic flow,
2:43
or how much the sound waves change as they move.
2:46
Acoustic flow is similar to optic flow,
2:48
where objects become visually distorted as you move.
2:51
Glancing out a car window gives your brain a pretty good sense of how fast
2:55
you’re moving based on how much the objects blur.
2:57
Many animals rely on optic flow to help navigate and gauge their speed,
3:01
so researchers are keen to understand how other senses contribute to these skills, as well.
3:06
Speaking of speed,
3:07
isn’t it impressive how fast cockroaches
3:09
can scurry without tripping over all those little feet?
3:12
Despite their smallness, they regularly clamber over relatively enormous obstacles,
3:17
often to the displeasure of any humans around.
3:19
Researchers wanted to learn more about their epic parkour skills,
3:23
so they built their cockroaches some treadmills.
3:25
The treadmills were spherical so that the researchers could track
3:28
the bugs as they traveled long distances in multiple directions.
3:33
It was additionally studded with various obstacles, in both sparse and dense arrangements.
3:38
Then the researchers turned cockroaches loose on the treadmill,
3:40
and settled in to see what they’d do.
3:42
Why does that kind of remind me of Maze Runner? This experimental design was really clever
3:44
because most maze-type experiments are limited by however big you can make your maze.
3:49
Even if you substitute a standard treadmill, it’s hard to add obstacles.
3:53
The spiky obstacle sphere solves both these problems!
3:57
And, it lets the researchers track the cockroaches
3:59
over long distances and for relatively long periods of time,
4:03
all within a pretty compact space.
4:05
For example, one of the bugs spent 25 minutes navigating a cluttered environment,
4:09
and traveled more than 67 meters, which is about 1,500 times its body length.
4:15
Extended data collection like this tells the researchers
4:17
about the ways cockroaches move during long distance journeys.
4:20
They found that the cockroaches adapt their movements to the environment.
4:24
Instead of just walking, they also climbed, rolled through gaps, and occasionally just... paused.
4:29
Presumably, they were in great shape afterward as well.
4:31
While the cockroaches were having fun on their treadmills,
4:34
some jumping spiders were playing video games.
4:37
Sort of. But for science!
4:38
The researchers leading this study wanted to understand
4:41
how well jumping spiders can see.
4:43
And the experiment they designed was pretty bonkers.
4:46
They glued little magnets to the jumping spiders’ heads,
4:50
then connected a little pin to the magnet,
4:53
like a tiny leash to keep them tethered to the experimental apparatus:
4:57
a small polystyrene ball.
4:59
Next they plopped the tethered spider into basically a spider-sized IMAX theatre,
5:04
with projections of a virtual reality world everywhere in sight.
5:08
Okay now this one reminds me of The Matrix.
5:11
To navigate the Matrix—I mean the virtual space—
5:14
the spider would move its feet and rotate the little ball,
5:17
which basically served as a tiny treadmill.
5:20
Or a computer mouse trackball.
5:21
As they rotated the ball, the projected image would shift,
5:24
in pretty much the same way VR headsets work for humans.
5:27
And, also pretty much like humans,
5:29
the spiders seemed to understand what the VR world
5:31
represented and were able to navigate it the same way they would the real world.
5:36
In other words, the researchers didn’t find many differences
5:38
between the way spiders behave in the real world and virtual worlds.
5:42
Things like how active they were and whether they sought out dark
5:45
hiding places were consistent from the real world to the virtual one.
5:49
Those experiments laid the groundwork
5:50
for follow up experiments to probe the details of jumping spiders’ vision.
5:55
For example, more recently a research team from the University of Cincinnati
5:59
projected dots of color onto a colorful background.
6:03
They were watching to see if the spiders attempted
6:06
to chase the colored dots through the VR landscape,
6:09
indicating the spiders’ ability to perceive different colors.
6:12
So far their preliminary results show that jumping spiders can distinguish
6:16
between ultraviolet and green, and some of them can also tell red and green apart!
6:21
The ability to learn their colors could be pretty important
6:23
for whenever the jumping spider Neo needs to choose between the red and the blue pill…
6:27
VR for spiders is a pretty high-tech piece of science,
6:30
but scientists are still trying to find good solutions
6:32
for much more low-tech problems,
6:34
like bottlenecks.
6:35
A “bottleneck” is a situation where a lot of objects,
6:38
animals, or people are trying to travel through a very small space
6:42
at around the same time,
6:44
frequently leading to jams.
6:45
Bottlenecks are a nuisance for concert-goers, coffee beans, and sheep, among others.
6:50
So for a lot of practical reasons, bottlenecks are a popular research topic.
6:54
Sheep are especially good bottleneck-ers because large groups of sheep
6:58
tend to get stuck when trying to go through small barn doors,
7:01
usually because they’re all in a hurry to get the food on the other side.
7:05
But unlike people, they aren’t influenced by customs of politeness.
7:08
Lest you be worried about the sheep-jams, they rarely hurt each other.
7:11
Must be all that cushy wool!
7:13
One common sheep-versus-doorway experimental setup
7:16
involves placing an object near the front of the doorway.
7:19
The sheep have to navigate around the object,
7:22
so it slows them down and helps them get through the door without getting stuck.
7:26
In one of these experiments,
7:27
the researchers placed a cylindrical concrete drainpipe
7:30
with a diameter of 114 cm in front of a 96 cm doorway.
7:34
Their test subjects were groups of 80 to 90 sheep, all of them about the same size.
7:39
They placed the barrier at distances of 60, 80, and 100 cm from the door.
7:44
When the barrier was only 60 cm away,
7:47
the group was slower than it was when there was no barrier.
7:50
But, compared to no barrier at all, the group got through faster
7:54
when there was a barrier at 80 or 100 cm.
7:57
So when put in the right spot, adding an obstacle in front of the door improved sheep traffic flow!
8:04
The strategy works for sheep
8:05
because they have to slow down to navigate around the barrier.
8:08
That prevents pile-ups from occurring at the door, and keeps traffic moving along.
8:13
Excellent results! Now let’s do this at concerts and sporting events, too please!
8:17
Unfortunately it’s not quite that simple for people.
8:19
Because while sheep are universally pretty rude to each other,
8:23
humans exist on a spectrum from very polite to incredibly impolite.
8:28
And that competitive aspect, or any element of panic,
8:31
might affect bottleneck behavior more than a well-placed barrier would.
8:35
So we’ll just have to keep researching other methods
8:37
to keep human traffic flowing smoothly.
8:39
Ants, on the other hand, are great in evacuation scenarios,
8:42
because they’re so good at cooperating!
8:44
To put those cooperation skills to the test,
8:47
scientists built an obstacle course containing three chambers connected
8:51
by two narrow doors and gave their tiny test subjects a T-shaped puzzle piece
8:56
to maneuver through it.
8:57
What is this... an obstacle course for ants?
9:00
If you’ve ever tried to move a sofa into a new apartment,
9:02
you probably know how those ants felt.
9:04
If you’re wondering how the researchers convinced the ants to take up the challenge,
9:08
the puzzle piece was basically marinated in stinky cat food and canned tuna.
9:12
This inspired the ants to get their puzzle piece back to the colony at all costs,
9:17
because who doesn’t enjoy catfood stink?
9:20
But here’s the punchline:
9:21
The researchers gave the same task to a crew of humans.
9:24
And the ants were way better at solving the puzzle.
9:27
The humans’ puzzle piece, by the way, was unmarinated.
9:31
Because if you don’t mind some very unscientific speculation,
9:34
the results would have been very different for humans
9:37
forced to maneuver a giant T-shaped piece of catfood stink.
9:41
Taken together, the results of the research
9:43
suggests that the ants were using a kind of short-term collective memory.
9:47
Okay now this is reminding me of the Borg!
9:49
On the other hand, the humans have to talk it out, reason with each other,
9:53
and align on a strategy in order to solve the puzzle.
9:56
While ants just do what everyone else is doing.
9:59
This works for the ants because as they collectively pull an object in a single direction,
10:03
the group continues to move in that direction,
10:06
even when they hit a corner.
10:08
This persistence lets them gradually work the puzzle piece through the opening.
10:12
Interestingly, this kind of wordless teamwork doesn’t seem to help humans.
10:16
When humans are given a similar task and told not to talk to each other,
10:20
they tend to pick the most direct-looking way out of the puzzle,
10:23
even if the indirect way is more efficient.
10:26
To be fair, evolution has let ants excel at cooperation
10:30
and problem solving through large group mobilization.
10:32
Even though they can’t really comprehend a problem in its entirety, they don't need to!
10:37
They just use short-term memories of collective group motion to solve the puzzle.
10:42
All of these examples revealed insights
10:44
about animal sensing, behavior, and navigation.
10:47
That just goes to show the huge potential
10:49
that mazes and obstacle courses have for helping scientists understand the ways animals think!
10:54
There’s no telling what kind of animal escape rooms scientists might concoct next.
That Time We Put Spiders in VR - Video học tiếng Anh
