In addition, there are three hypotheses about the production process of speech and gesture: the Free Imagery Hypothesis (Krauss et al., 1996(Krauss et al., , 2000de Ruiter, 2000), the Lexical Semantic Hypothesis (Schegloff, 1984;Butterworth & Hadar, 1989), and the Interface Hypothesis (Kita & Ö yzürek, 2003).
this hypothesis predicts that gestures do not convey the information which is not encoded in the accompanying speech.