Gestures may contribute to the meaning of an utterance not only by adding information but also by modifying the gestural or verbal content uttered in parallel. The phenomenon of modification is more common in natural interaction than it has been given attention. We created a corpus of natural communicative gestures and body movements and conducted a study to examine their modifying functions. Results show that index-finger-pointings are most prominent, which emphasise and affirm an uttered content and, thus, are not only used for referencing but also for modifying. Holds emphasise and colour the utterance by showing a stance towards something. Brushing gestures change the utterance in a discounting or downtoning way. A cluster analysis suggests four distinct categories: a focusing category for emphasising an aspect, an epistemic-attitudinal category to convey one’s own stance, an epistemic category for uncertainty, and a category where multiple viewpoints are discussed.