Hsu's (1994) study, which was designed around a hypothesis drawn from interactionist SLA research, investigated learners' use of interactional modifications in a CALL activity intended to improve listening comprehension of adult ESL learners. She conducted a focused discourse analysis of interactions between learners and the computer to identify their requests for modified input within a listening comprehension program. The normal interaction in this part of the program consisted of learners' requests for continuation of a story with accompanying pictures on one computer screen. The researcher counted as "interactional modification" sequences in which this normal interaction was interrupted by the learners' requests for repetitions, written transcriptions, or written definitions for words in the input. An example of the type of the observed interaction follows:

She also identified the specific linguistic input associated with each of the learner's requests. Hsu assessed outcomes through pre- and post-tests which had been constructed specifically for her research to include the lexical phrases learners would receive in the input. Among the findings was a significant relationship between interactional modifications and improvement in listening comprehension on the specific lexical phrases with which the modifications had occurred. Research like Hsu's provides some evidence that hypotheses about SLA which were formed on the basis of research on communication among human participants might also apply to some human-computer interactions. Such research must be conducted by combining a theoretically-motivated description of the moves during a CALL activity with assessment of outcomes based on a context-specific definition of language ability (e.g., listening ability for particular lexical phrases).