PARRY was an early example of a chatterbot, implemented in 1972 by psychiatrist Kenneth Colby. PARRY was written in 1972 by psychiatrist Kenneth Colby, then at Stanford University. While ELIZA was a tongue-in-cheek simulation of a Rogerian therapist, PARRY attempted to simulate a paranoid schizophrenic. The program implemented a crude model of the behavior of a paranoid schizophrenic based on concepts, conceptualizations, and beliefs (judgements about conceptualizations: accept, reject, neutral). It also embodied a conversational strategy, and as such was a much more serious and advanced program than ELIZA. It was described as "ELIZA with attitude". PARRY and ELIZA (also known as "the Doctor") "met" several times. The most famous of these exchanges occurred at the ICCC 1972, where PARRY and ELIZA were hooked up over ARPANET and "talked" to each other.