A series of quasi-experimental field studies (n(1) = 37, n(2) = 117, n(3) =
113) analyzed the impact of task characteristics and of the subjects' proc
edure on the carrying out of delayed repeated time-based intentions. The pe
riod covered by the tasks varied from 2 to 14 weeks. The main issue is whet
her time-based "prospective memory" or memory for delayed intentions in non
-deprived real-life settings is based on spontaneous self-initiated retriev
al (Einstein & McDaniel, 1996) or on environmental support (Rabbit, 1996).
People rely on neither spontaneous activation nor on automatically emerging
cues but generally seek or design a self-initiated support system in takin
g upon the delayed tasks and redefining them into a retrieval-supporting ve
rsion. The rate at which tasks are carried out is significantly higher with
people who seek and design support. However, the elaborating self-planning
of intentions per se, without an enlargement of cues or tagging, does not
improve retrieval. Although a prescribed external cue and a context-related
type of dare did not improve performance, they did prevent its deteriorati
on for weeks. If no such support is provided performance decreases over the
period of delay, whereas response spacing and repetition frequency are of
no effect. The cited alternative of spontaneaus retrieval vs. environmental
ly cued task realization should be replaced by their cooperation. A related
model is outlined.