Psychology is critical for product designers to master and use with today’s new web products. “Ease of use” doesn’t motivate users like people once argued it did. It sounds sick, but you’ve got to manipulate people’s minds to build a wildly successful product.

Flash sales sites are probably the simplest example of how to employ psychological techniques successfully. Here are a few of the concepts they employ:

Scarcity

OK, this is a little bit of economics too. Scarcity is the concept that a resource is limited. When a user thinks the item they’re looking at isn’t going to be available much longer, there’s a strong incentive to act.

Fab.com shows you when inventory of a particular product is low and also shows the ones that have already sold out. It’s like they are saying, “Act quick to get this watch or you’ll miss out on this great product like you did on all these other ones.”

Curation

Giving the perception that items are curated by professionals that do the thinking for you removes a big barrier to buying goods online. Instead of relying on your own limited knowledge or reviews by other users, a professionally curated selection means you aren’t going to get a product that lets you down. “We know you’ll love this box of wine!”

Who has time to become a wine expert? Many of us would like to, but it’s too much work. Lot18 knows this and in addition to getting great deals on wine, they make sure you know you’re getting professionally selected wine that you and your guests will love.

Deals

Giving the customer the perception of saving money is a pretty timeless motivator. They all do this and don’t be surprised if the “retail prices” get more and more inflated as the economy improves!

Emails

Fred Wilson likes to remind people that email is a startup’s best friend. Unless your site is one of the 7 that people visit in their daily routine, email is critical to getting users re-engaged. In Fred’s post, Etsy’s number one driver of traffic to their site is their series of emails they send out.

OpenSky does a really great job of this as well. On their platform, you select the celebrities/influencers you’d like to follow. For some reason I followed Bobby Flay and now any time he posts a new product for sale, they email me about it.

It seems simple and obvious to be emailing your users, but I know myself and a lot of other product designers that have failed to have a thoughtful email strategy and it hurt.

You need to go beyond a simple email newsletter with product updates. Look at how successful social networks all have great email notification strategies.

So Many More

These sites do many other tricks to press people’s buttons and they are constantly adding new ones (Fab.com just added a public feed of all user activity on the site). There is a lot of innovation going on in ecommerce and it’s proving to be a war fought in the consumer’s mind.