Word capture

People usually feel comfortable when talking to others they know.  Most personality types feel comfortable making conversation with people they don't know.  But when people feel out of their comfort zones, they try not to talk unless forced to.  When people get on elevators, they tend to clam up, not feeling the compunction to make even small talk with other occupants.

If someone has been accused and has to give a deposition for an attorney, if someone has to make a statement to a detective, or if someone has to talk in front of cameras unexpectedly, then the speech changes.  It is not a natural situation.  They are forced to talk.  That uneasiness is captured in words believe it or not.

The beauty of such captured words is that people cannot tell that their speech changes, it's so subtle.  It happens below the conscious level.  Unlike polygraph tests that measure nervousness and temperature rises, speech changes are so unapparent it can't be controlled even if the person knows what the changes are.  A person would have to know what changes about speech and practice it for a long time to fool the speech change test.

When a person begins speaking, and continues for any length of time, a comfort mechanism forces the language into a certain range of words being used.  The range is not a set range of words, but unique to each person's vocabulary base.  A quantity-based value for this range, called the type/token ratio, can be established.  The more and the longer one talks, the more the baseline of the ratio becomes certain.  A second statistical test performed on the range on various segments of his speech reveal the areas where misleading speech has been made.  Choices of vocabulary might be important to other types of analysis, but word choice semantics in the type/token ratio analysis are not important.

Such an analysis makes the 5th amendment an important principle if someone knows that a forensic linguist is in on a case.   Incrimination is the name of the game.