Is Time Moving Forward Or Backward? Computers Learn To Spot the Difference

sciencehabit (1205606) writes For the first time, scientists have taught computers to figure out the direction of time in videos, a result that could help researchers better understand our own perception of time. Regardless of any possible applications, "we just thought it was a great problem," says one of the study's authors. Teaching computers to see the arrow of time combines computer science, physics, and human perception to get at the heart of the question, "How do we understand the visual world?" The researchers "broke down 180 YouTube videos into square patches of a few hundred pixels, which they further divided into four-by-four grids. Combining standard techniques for discovering objects in still photographs with motion detection algorithms, the researchers identified 4000 typical patterns of motion, or 'flow words,' across a grid’s 16 cells. ... When they tested their program on the remaining 60 videos, the trained computers could correctly determine whether a video ran forward or backward 80% of the time."

Comments

Easy

[ZombieBraintrust]

Beginning

hey guys..

End

Click Like To Subscribe. Follow Hashtag blah on twitter, blah blah reddit. Hand waves to bottom of screen.

Re:Easy

[ZahrGnosis]

Actually, if you guessed that a randomly selected set of youtube videos were being played, you know... FORWARD, you'd probably be correct more than 80% of the time without having to actually think at all. I assume their 80% result was based on something more difficult, but it's still kind of a silly sounding number without context.

Re:Easy

[Dcnjoe60]

But the point is not to tell if sound is moving forward or backwards.

The point is to detect if a video (possibly even without sound) is moving forward or backwards.

But you could easily mess up this program by showing it a video of Michael Jackson doing the Moonwalk.

However, whether detecting if sound or video is moving backwards or not has nothing to do with detecting if time is moving backwards or not. Playing a file backwards still occurs with time moving forwards.

How'd it do on Top Secret?

[Overzeetop]

https://www.youtube.com/watch?...

(and..."Europe on 5 Quaaludes a Day," forward version: https://www.youtube.com/watch?...

I know

[nitehawk214]

I will call you yesterday and let you know.

Re:I know

[geekoid]

I was in yesterday, and you never called.

time or not

[buswolley]

This means nothing. It is not detecting time per se. It is detecting things violations like objects don't fall up, or other such experienced pattern that is the result of time.

Re:time or not

[rogoshen1]

Hi gnick, this is your boss. Step into my office please.

ok

[hurfy]

If I close my eyes and say "forward" what percentage do I get right?

Re:ok

[Carnildo]

More significantly, if you see left-to-right motion and say "forward", what percentage do you get right? I suspect there's a bias in videos towards left-to-right motion of subjects (or conversely, right-to-left motion of backgrounds), and I don't see anything in the paper about controlling for it.

Sounds like bad methology

[imsabbel]

You tube videos? And analysation on block level?

Won't the fact that the video codec has a direct timeline (with predictive frames, etc) override the rsults?

Re:Sounds like bad methology

[Minwee]

Be quiet! You'll jeopardize our funding.

Re:Sounds like bad methology

[mrbobjoe]

Good question about the codec, they took that into account somewhat by including a dataset that used a codec with only intra-frames (I imagine this was MJPEG).

From section 3.3:

We also filmed a small number of video clips using a camera which could record in a video codec which used only intra-frame, rather than inter-frame coding, meaning that there was no possibility of compression artefacts holding any time-direction information. This dataset comprises 13 HD videos of tennis balls being rolled along a floor and colliding with other rolling or static balls.

The algorithms tested did well on this dataset as well, 12/13 classified correctly.

Re:Sooo....

[clam666]

Is that the only measure of success?

...and this is why the terrorists are winning. If you're in 'murica, get some Jesus. If you aren't, stop takin' meh jobs!

Re:Time isn't moving at all

[sjames]

If you prefer, now moves through time. At the quantum level there is no directional preference yet at the macro level, there is a distinct preference. Why that is so is an open question.

Oh really?

[ArcadeMan]

Have they tried their software on the music video Amish Paradise by "Weird Al" Yankovic?

Re:Sooo....

[Dishevel]

This saves us from the terrorists how?

Is that the only measure of success?

Not. It is not the only measure. We also measure success by thinking of the children. Any other questions?

Re:Time isn't moving at all

[kruach aum]

For space to be able to travel there needs to be some frame of reference against which it can be judged to have travelled. As the frame of reference for travel is space itself, if space could travel we wouldn't be able to tell.

Abrupt transitions in optical flow?

[RandCraw]

Dr Freeman spoke about this work at CVPR this week. In the videos I saw he identified small markers of temporal transition as indicative of moving forward or backward. Those they labeled as backward appeared to recognize asymmetric movement -- as in gradual acceleration followed by sudden deceleration as uniquely forward flow (as when a hand swings down and strickes a table top) -- an asymmetry that cannot occur in reverse (as in sudden acceleration followed by gradual deceleration).

Dr Freeman did not propose this as the causal phenomenon in question, but that made the most sense to me in light of the motions he identified as evidence for backward motion.