Key Wordsrn- Modificationrn- Compressibilityrn- Interlanguage utterancesrn- Target-like usernThe purpose of this study was to investigate whether students modified theirrninterlanguage utterances towards comprehensibility and/or target -like use when theyrnexperienced difficulty in message comprehensibility during task- based interactionrnwhich involved only students. To this end, twelve students of Grade 12 at EnjibararnComprehensive, Preparatory and Technic School were selected and participated in thernstudy. These students were paired up and made to interact using a picture-dictationrntask. Their interactions were tape- recorded, transcribed and analysed.rnThe results of the anlyses indicated that the participants were able to successfullyrnnegotiate for comprehensibility by modifying their trigger utterances in 30(63%)rninstances of the one-signal negotiated interactions. The findings of the study alsornrevealed that when the participants generated modifications of initial utterances, theyrnmade use of target-like forms in 70% of the cases. However, when the rate ofrnfrequency of these modifications which exhibited the use of target-like forms wasrncompared with the total number of responses made to clarification requests, it wasrnfound minimum, i.e. 44%.rnFurthermore, the investigation made to see why the participants did not engage in thernmodification of their trigger utterances more often than they did resulted in thernknowledge that a particular type of incomprehension signal called trigger repetitionrnsignal was responsible for this situation. This signal type was found less effective inrnrnprompting the participants to modify their trigger utterances. Of the 48rnincomprehension signals made in the one-signal negotiated interactions, 23(48%) ofrnthem were trigger repetition signals. However, only 11(36%) modified comprehensiblernoutput instances were made in response to this signal type. The majority number ofrnresponses (64%) were made in reply to either trigger modification signals or explicitlyrnmarked signals which accounted for 25% (12) and 27% (13) of the total number ofrnincomprehension signals, respectively.rnFinally, conclusions were drawn based on the findings of the study and suggestionsrnwere made for future research on the area.