Social science is a study of human behavior in all his environments. Human beings are social creatures and most likely to belong in a community to be able to feel secured and safe. Human interaction is essential for a sane mind. A branch of topics in social science is called body language. Many would argue that it is not a reliable science as it cannot be measured or evaluated objectively. But most would agree that body language can determine the hidden or unspoken message a person is trying to selectively communicate. Some experts in the field have been hired to identify and convict criminals or merely to screen who is telling a lie and who is telling the actual truth.
You fold your arms in front of you when you were talking to an annoying co-worker and just seconds later, that person leaves your company. Subconsciously, you have giving that person to back off since you do not feel comfortable with him around. You might be trying your best to hide your disdain for the person when you are talking but somehow your folded arms screams back off. This is the wonder of body language - it actually mirrors what you actually think or feel even if you do not say anything at all.
Most of the time, talking or verbal communication only takes 10% and 90% is being garnered by the non-verbal communication during social interaction. That is why body language is important in decoding those 90% of unsaid emotions, thoughts, or opinions. If you have a very high emotional quotient then you can easily read other people so to speak. You can sense their true emotions and it can tell you how they actually feel.
For most people, finding out if a person is lying to you seems to be prevalent. Of course, lying is different from not telling you entirely. But for the purpose of demonstration, let us say that lying is being observed in an interrogation room wherein a suspect and a police investigator is having the procedural interviews.
The suspect seem to be feeling confident and not shaking. The investigator knows that the suspect can or cannot be the culprit behind the crime. So on the the other side of the one-way mirror, a psychologist or sociologist will observe the suspect. They take not of every clue that the suspect can give away - like tone of voice, sweat, hostility, etc. all sorts of emotions and try to define a conclusion. This conclusion is discussed with the police and the law enforcers often have sets of questions that can draw out the real emotions of the suspect. Based on the conclusion, the investigator finds concrete evidence to back up the claims or accusations. If the suspect touched his nose, covered his mouth, touched his neck or ears or other fidgeting mannerisms, then he can be hiding something.
Small physical actions can be taken into account by expert people reader. They might draw far out conclusions but they are usually correct. The science of body language is readily being given to law enforcement, educational, and industrial sectors when they are needed. In recent years, new ways of investigation has acknowledged the capability of body language in solving cases and even just by telling if someone is being cross with you.