PARRY: A Simulation Model of Paranoia

Background

PARRY was a computer simulation model of paranoia developed in the 1970s at the Stanford Artificial Intelligence Laboratory and at the Department of Psychiatry at UCLA.

The PARRY program simulated a paranoid patient, while the user/psychiatrist conducted a diagnostic interview with PARRY via a computer terminal. PARRY responded to questions posed in ordinary, unrestricted English, introduced its own topics, and dealt with threatening or shame-producing situations.

PARRY ran nightly on the ARPA network for many years with more than 100,000 interactions. Lists of notable early chatbots typically include PARRY along with ELIZA, A.L.I.C.E., and Jabberwacky/Cleverbot.

Faithful Reimplementation

Available here is a faithful reimplementation for more recent computers of PARRY version 2. The program is a 32-bit stand-alone Microsoft Windows console application. (The program can run under either 32-bit or 64-bit MS Windows operating systems.)

Click here to download the zip file containing the program executable, data files, and instructions.
The parry.zip file (updated Mar. 10, 2026) has these checksums:
SHA1: 476903b864c2206e73505177e570bac3fed7227f
MD5: 5db820308d60d8abcb53ec4b1120f2df

Click here to download a zip file containing some sample dialog files produced by this MS Windows version of PARRY.