Peter Hall Effect
      
      
        An ApproachAvoidanceGradient effect discovered by Peter Hall of LimpinWood. 
      
      
        - 
           Observe any cloud of midges at dusk. 
          
            - 
               Sing a pure tone to them and the cloud will expand. 
            
 
            - 
               Lower the tone and they contract. 
            
 
            - 
               Oscillate it and you can dance with them. 
            
 
          
         
      
      
        Not to be confused with the HallEffect