Sixty pairs of University students participated in referential communication tasks with Tangram figures. Using referential communication paradigm, the present study aimed at investigating the effects of cognitive artifacts employed in the conversation. The members of the pairs, who were familiar with each other, were randomly assigned to either a director or a matcher. The task for the director was to give a information to her/his matcher so that she/he could identify 8 Tangram figures in order. The six trials were given in different order to the pairs. The pairs were randomly assigned to the one of 4 communication channel conditions; same room separated by screen, or different rooms using a telephone with 3 levels of interference noise (none, low and high). Even though task performance was not affected by communication channel conditions, there were substantial differences in the variety of communicative tools employed in the dialogues, especially in the first trials. Qualitative and quantitative analyses of the conversations showed; (a) in the screen and no interference telephone conditions, participants frequently described the figures in detail and with reference to geometrical forms, but not for the telephone interference conditions, (b) participants in the low interference telephone condition employed more metaphoric expressions for small parts of the figures, whereas the participants in the high interference condition tended to use metaphors for the whole, a strategy which was effective when the pairs shared common ground, but less so when this common ground was missing, (c) in the high interference condition, the number of reference units was small in the first utterances, but increased in response to the matcher's feedback. The three kinds of feedback from the matcher (requests for repetition, clarifications, and questions) illustrated the cooperative nature of constructing common ground in conversation. The results show that changes in conversation due to interference can be explained in terms of reduced attention and/or changes in strategies used in making conversation.