body language analysis Body language is instinctively interpreted by us all to a limited degree, but the subject is potentially immensely complex. Perhaps infinitely so, given that the human body is said to be capable of producing 700,000 different movements .

As with other behavioural sciences, the study of body language benefited from the development of brain-imaging technology in the last part of the 20th century.

This dramatically accelerated the research and understanding into connections between the brain, feelings and thoughts, and body movement.

We should expect to see this effect continuing and providing more solid science for body language theory, much of which remains empirical, i.e., based on experience and observation, rather than scientific test.
Given the potential for confusion, here are some considerations when analysing body language:
context
Body language also depends on context: body language in a certain situation might not mean the same in another.
Some 'body language' isn't what it seems at all, for example:
Someone rubbing their eye might have an irritation, rather than being tired - or disbelieving, or upset.
Someone with crossed arms might be keeping warm, rather than being defensive.
Someone scratching their nose might actually have an itch, rather than concealing a lie.
sufficient samples/evidence
A single body language signal isn't as reliable as several signals:
As with any system of evidence, 'clusters' of body language signals provide much more reliable indication of meaning than one or two signals in isolation.
Avoid interpreting only single signals. Look for combinations of signals which support an overall conclusion, especially for signals which can mean two or more quite different things.
culture/ethnicity
Certain body language is the same in all people, for example smiling and frowning, but some body language is specific to a culture or ethnic group.
See below.
Awareness of possible cultural body language differences is especially important in today's increasingly mixed societies.
Management and customer service staff are particularly prone to misreading or reacting inappropriately to body language signals from people of different ethnic backgrounds, a situation made worse because this sort of misunderstanding tends to peak when emotions are high.
Personal space preferences (distances inside which a person is uncomfortable when someone encroaches) can vary between people of different ethnicity.
In general this article offers interpretations applicable for Western culture.
If you can suggest any different ethnic interpretations of body language please send them and I'll broaden the guide accordingly.