Levy (1997) explained that the metaphors of computer-as-tutor and computer-as-tool emerged out of conceptualisations of tutorial and nontutorial distinctions (Higgins 1983; Taylor 1990).
The CALL field instead embraced the metaphors of tutor and tool (e.g. Levy 1997), and more recently ecology (e.g. Lam and Kramsch 2003), to conceptualise the use of technology for language learning.