According to most current theories, it is assumed that skill acquisiti
on is based on a continuous and data-driven learning Process. Our main
goal in the Present article is to demonstrate that these assumptions
are severely limited. A review of the main theories of cognitive skill
acquisition is followed by a summary of our own research on the topic
of ''information reduction'' (Haider & Frensch, 1996, submitted-a, su
bmitted-b). Our results show that the process of skill acquisition can
be accompanied by a decline in the amount of information that is cons
idered when a task is processed. Information reduction appears to be b
ased on active selection of task-relevant information. Data from 6 sin
gle-case studies and re-analyses of earlier data strongly suggest that
the experimental tasks used in our own research lead to discontinuiti
es in learning curves, implying that the process of skill acquisition
can be both continuous and discontinuous. These findings and their imp
lications are discussed and an extension of the present theories is pr
oposed.