Expressive Language includes Conceptualization, Symbolization, Mixer and Transduction processes.
 
 
For Expressive Language we still must take into account within each modality, those expressive processes we have been discussing:  
Conceptualization, and 
- Symbolization, and
 - Mixer, and 
 - Transduction.
 
The inability to bring to mind a Concept (idea) we would like to express is experienced by most of us under conditions of increased stress.  
In the Auditory modality, when we confront a sea of faces in an audience, the lines we have memorized for a play, or the speech we have planned for the occasion may all vanish into thin air.  
Instead we look out with a blank stare helplessly unable to draw a single thought to our mind which could open the floodgates of communication.  It is referred to as "Stage Fright."
NOTES:  Here is a cute story about stage fright by Mark Twain