I just read via SearchEngineWatch.com that Google will be rolling out the +1 button on display ads. You’ll be able to “+1” the ad as well as see the number of others who have done so along with photos of those who have plus-one’d within your network.

I do believe that social signals such as +1 will positively affect two major metrics for display advertisers:

1) Engagement time with the advertisement will increase. When the ad is displayed, if you see people in your circle who have +1’d the ad, you’ll apt to look at the ad for a longer amount of time. This will increase recall for your display ads.

2) CTR. Your click-through rates should increase as well, with heavy increases weighted to those people being show the ad who have other’s in their network who have +1’d it. Simply put, social signals usually equal higher CTRs.

Now for the downside:

3) Bounce rate. Social signals mean higher CTRs, but those clicks may not be relevant. They may fall in a category which I refer to as “curious clickers”. People who are interested in the ad, but not necessarily the product.

4) Google says that the +1 will be for the URL behind the advertisement. So if I show an ad for a cute cat and you +1 it, but then I change the ad to a dog, it still looks like you have +1’d my ad. Obviously, this could create big problems, so I’m sure that Google will work out a way of preventing this “+1 and switch” potential. They just haven’t explained how they are going to do that yet.