  This paper examines the phenomenon of daydreaming: spontaneously recalling or
imagining personal or vicarious experiences in the past or future. The
following important roles of daydreaming in human cognition are postulated:
plan preparation and rehearsal, learning from failures and successes, support
for processes of creativity, emotion regulation, and motivation.
  A computational theory of daydreaming and its implementation as the program
DAYDREAMER are presented. DAYDREAMER consists of 1) a scenario generator based
on relaxed planning, 2) a dynamic episodic memory of experiences used by the
scenario generator, 3) a collection of personal goals and control goals which
guide the scenario generator, 4) an emotion component in which daydreams
initiate, and are initiated by, emotional states arising from goal outcomes,
and 5) domain knowledge of interpersonal relations and common everyday
occurrences.
  The role of emotions and control goals in daydreaming is discussed. Four
control goals commonly used in guiding daydreaming are presented:
rationalization, failure/success reversal, revenge, and preparation. The role
of episodic memory in daydreaming is considered, including how daydreamed
information is incorporated into memory and later used. An initial version of
DAYDREAMER which produces several daydreams (in English) is currently running.
