Thanks to Skillshare for supporting this episode of SciShow.

Click the link in the description to learn more about Skillshare. [ ♪ Intro ]. If you've ever run your fingers over a comfy blanket or buried your face in a fluffy cat after a bad day, you're familiar with just how nice the sensation of softness can be.

And people are willing to pay for it. You'll see bed sheets proclaiming the sumptuous goodness of Egyptian cotton or cashmere scarves retailing for a small fortune. But why do cashmere and these other soft fabrics feel so soft?!

Well, the answer isn't completely clear, but it seems to involve two main components: the properties of the material you're touching, and you. Or rather, your brain. Fabric hand, or handle, is the term the textile industry uses to describe the way a fabric feels and moves when you touch it.

For years, scientists who study fabric hand have been trying to relate the subjective words we use to describe textures, like “soft” or “crisp”, to properties they can actually measure. And it can get pretty complex. The feel of the fabric can be influenced not just by the material properties but also by the way you touch it and whether or not you're actively moving your fingers over the material.

And your definition of “soft” might not match mine, which makes things even more complicated. Despite this, scientists have pinpointed material properties that could be related to softness. These can be split into two main groups: how smooth the fabric is, which includes properties like friction and surface irregularities, and how easy it is to compress, which includes properties like the flexibility of the fabric.

So a bean bag sofa is soft not only because of its fabric casing, but also because you can squish it really easily. But soft doesn't necessarily mean you have the smoothest, most compressible object in the world. A 2006 study showed that even though alpaca fiber was 10 times as rigid as wool, we encounter less friction when touching alpaca, so it feels softer.

So material properties are part of the story, but clearly there's more to it. And that “more” is in our brains. We don't understand everything about how it works yet.

But two psychology studies that examined how people rated the softness of compliant objects may provide clues as to why. Compliance, which can be measured by compressing an object, is a way of describing how objects deform when they are subject to forces. In 1995, scientists found that your perception of softness could be related to the way that pressure is distributed on your fingers as you move them over an object.

At least in the case of objects with deformable surfaces, not so much for rigid ones. The researchers performed a series of experiments that involved, among other things, people using their finger to press down on rubber, and having rubber pressed down on their finger. The results suggested that tactile information is enough to tell us whether something's soft.

This information is communicated by mechanoreceptors in our skin that work by sensing differences in pressure on your skin when your finger touches an object. A study in 2008 extended these findings and found that people tended to rate rubber objects as soft if they were more compliant or deformable than the human finger, and hard if they were less compliant. So whether you're petting your dog or just gliding your hand over a bunch of luxurious cashmere scarfs, there's actually a lot going on to bring you that lovely experience.

So, cashmere scarves are a treat to touch. But cream mixing with coffee can be a treat for your eyes. Just picture it, a nice glass of cold brew with that perfect swirl of cream.

And if you wanted to capture that moment forever,. Skillshare offers a course on how to photograph coffee swirls. In the class “Cold Brew Coffee Swirl,” Tabitha Park takes you through the whole process, from choosing the right coffee and cream to editing your shots.

And that's just one of the over 25,000 classes on Skillshare, which is an online learning community for creators. Premium members get unlimited access to those classes, so you can browse them all and find what you need to jump start your creativity, or your career. And right now, the first 500 SciShow subscribers to sign up using the link in the description will get a 2 month free trial.

So check it out and get learning! [ ♪ Outro ].