Yet I predict that in the future we are going to make much more use of cameras. Not because we start worrying less about our privacy, but because we can do such cool stuff with them, that we cannot help ourselves to use them.

The first year students of Psychology and Technology that I teach recently got the assignment to do an experiment replicating a paper published in 1983 in Science. Researchers showed that people who are angry have a higher heart rate than people who are happy. Physical properties such as your heart rate can therefore tell us something about how you feel.

In the original study, the researchers used sophisticated equipment and computers to measure heart rate. My students successfully replicated the experiment - with their smartphones. With a free app that measures the redness of your skin, which is an indicator for the dilation of your blood vessels, the camera on your phone can be used to reliable measure a person's heartbeat. So you are carrying a laboratory in your pocket, with which you can gauge how other people feel.

I can already see what will happen. In a few years, our students will create an app for your smartphone that you can aim at the person you are talking to, and with which you can literally see if you make the heart of that person beat faster. 110 beats per minute? Shall we skip desert and go back to your place right away?