Simple Language Processing: ELIZA

Weizenbaum's ELIZA program simulated a Rogerian psychotherapist; it achieved surprisingly good performance simply by matching the ``patient's'' input to patterns:

Pattern:   (I HAVE BEEN FEELING *)
Response:  (WHY DO YOU THINK YOU
             HAVE BEEN FEELING *)

Patient: I have been feeling depressed
           today.
Doctor:  Why do you think you have been
           feeling depressed today?

• Huge number of patterns needed.

• Lack of real understanding:

  
  Patient: I just feel like jumping
             off the roof.
  Doctor:  Tell me more about the roof.