your dog forgot that you were even there. Hello, everyone. Thank you for watching DNews today. I am Trace.

But, before we get into animal memory, make sure you stay to the end of this video for a HUGE announcement…

So, an elephant NEVER forgets Flipper! No one you see, is smarter than he!

My dogs and cats miss me when I'm not there... We are constantly personifying the smarts of our animal friends,

but how would you actually TEST this?

In a 2014 issue of Behavioural Processes, a researcher from Stockholm University tried to do just that.

Using delayed matching-to-sample training, researchers tested the memory retention of 25 species including chimpanzees,

dolphins, seals, crows, dogs, rats, macaques.

They trained each animal to look at a colored light and then

presented them with a choice of two colored lights later. If the animal "remembered" the correct light they were rewarded!

In this way, they could test over and over again and

see how long an animal could remember which one they've seen first. Rats performed the best

when there was no delay between the first light and the second two lights, but dogs were the best as the delay increased!

But don't get too excited. It turns out, dogs have an arbitrary short-term memory of a little over two minutes and

our genetic cousin the chimpanzee was completely average at around a minute. Just kind of impressive, which shows that at some points,

six million years ago when we branch off from chimpanzees, we developed an arbitrary memory. And, they didn’t. That's kind of cool.

Humans, for comparison can easily complete this task 48 hours later. The thing is, memory is really… uh… what's the word? DIFFICULT to test.

The researchers acknowledge this only testing the arbitrary short term memory. Dolphins, who scored second highest,

have been documented to recall the whistles of their friends even 20 years later because of this different kind of memory.

Elephants can remember trauma, family members or friends over long periods of time as well.

So does my dog REALLY forget me when I leave the house? No. Not REALLY.

This research shows that humans have a VERY adept arbitrary memory. Stuff that doesn’t matter that much.

Matching a colored light to another one doesn't really affect your survival, and yet for some reason, our brain chooses

to store the information. Animals likely don't do that. Where humans use episodic memory -- as in we understand what happened,

what's happening now and what WILL happen in the future-- animals learn behaviorally. A dog knows it's time to eat,

not because they know it is five o'clock at night. They can sense how hungry they are, and on average, they have been trained that

they will receive food before work and after. Based on this and other research, people believe animals have an inferred memory;

they remember things that are relevant to their survival.

For example, a cat remembers where its food is when you go away for the weekend, but it probably

doesn't really know exactly how long you've been gone. A cheetah may remember, it had a kill this morning because

he's still full of food, or myabe which female or male cheetah mated with because its brain imprinted her scent

so he spreads his genes better, but that cheetah WON'T likely remember if it rained last week.

In the 1950s Psychologist George Miller determined humans can store seven "chunks" of information in our short term memory; give or take.

But the problem is, the more we really dig into how memory works the more nebulous the whole thing becomes.

Testing covert behavior -- or behavior we can't really see externally, is very problematic, because we can't see what is going on inside of the animals' heads.

And, we can't ask them what they're thinking. In the end, take any study like this with a grain of salt, even

the researchers say this is just one way to measure memory. So while your scent is probably

imprinted on your pet as a member of its pack or family, it doesn't remember that birthday card you bought her last year.

Instead, your pet is more concerned with things related to survival than the arbitrary joys you personify upon them,

but that doesn't mean they don't care! They just care differently than we do. How does this study make you feel though?

Let us know in the comment below. Make sure you subscribe for more DNews.

And now, that announcement I mentioned earlier. I'm really excited to announce the launch of our brand new sister show Seeker!

We take a science approach here on DNews. You probably know that. They take a look at the more human side.

Like in this video about a risky oil exploration of the Arctic!

The grounding was a major disaster and shockingly expensive for the oil. The mission cost an estimated six billion dollars and

they came away with nothing. So, the question is why are oil companies willing to take such giant risks?

Seriously! It’s a fantastic brand spanking new show and I know you're going to love it. Evan and Lissette are the best.

So go click the first link in the description and check it out! Thanks for watching.