This may sound a little bit like science fiction, but the technology is already here. The reason it is not used in any serious way is because detecting emotion is only half of the puzzle. Getting a computer to recognize the emotions it has detected is something that is a very big problem. It may simply be something that we cannot achieve with current computer technology.
Recognizing emotions technologically is easy
You may have heard of micro-expressions on a person’s face. These are very small movements that we make with our face without realizing it. The study of such a phenomenon is very interesting, for example, you can show a person a picture of a rotting carcass. Later on when you mention it to them, some people do a micro-expression with their top lip. This is a very small version of the face we pull when we smell something nasty. It takes cameras with very high shutter speeds to see it, but it can clearly be seen in some people.
The software to recognize emotions is not within our grasp yet
If you were to program a computer to recognize micro expressions, you would have to keep programming for years before you program the recognition of enough variations of micro expressions in order to gain any sort of useable result. Plus, the software would always throw out anomalous results because people are too unpredictable.
Some people produce different micro-expressions dependent upon the type of person they are. Going back to the rotting carcass experiment, what if the person who saw the picture was born without a sense of smell? The micro-expression regarding the top lip would not work. That person may actually narrow his or her eyes as he or she recalls the rotting carcass picture. Plus, how does a computer software program know the difference between a twitch and a micro-expression? A human can use some form of discretion, but this sort of artificial intelligence is hard to program into a piece of software.
The lie detector is similar to an emotion detector
A lie detector does not actually detect lies. There is no technology on the planet that is capable of detecting lies. The lie detector actually detects emotional responses that are connected to lies. It checks for elevations in blood pressure, sweating or temperature, as these are all things that may accompany an emotional response. This is one of the reasons why lie detectors do not work on the emotionally maladjusted, or the mentally ill, because the emotions they feel may not be attached to what others may attach them to (such as lies).
There is technology that can detect changes in pitch
Audio analysis technology is able to recognize changes in pitch and the “stress” in a person’s voice. Many people try to use these indicators as ways of figuring out if a person is lying, but again just like the lie detector, the software recognizes emotional responses that may or may not be associated/tied with a lie.
And yet again, this technology has similar problems to micro-expression recognition technology, in that people are simply too diverse and different to be able to judge one person by a set of standard rules. For example, we have all met the woman who talks with a tone of voice as if she has just escaped from a pack of rabid dogs. We have all met the man with the deep voice who always sounds sleepy. It would be too difficult to judge one person with a set of rules, and then another with a different set.
For example, some women in Asia have very high-pitched voices to the point where if a westerner heard her in ecstasy, he may mistake it for her being in distress. On the flip side, there are Asian men who believe that North American African Americans are aggressive because their tone of voice flips from high pitch to a low pitch very dramatically in one sentence.