The Situated Multimodal Facets of Human Communication - Coverbal Synchrony in Human-Machine Interaction - page 185

according to a stereotype point of view, the nature of the Italian
gestural repertoire is reputedly considered to be richer than those
of other speaker groups and my gesturing while speaking was an
exemplification of such a view. The careful analysis of video-recordings
of other speaker groups and personal discussions with experts in the
field (among those Sue Duncan, Adam Kendon and David McNeill)
proved that (to a large extent) gesturing is common to any worldwide
speaker and comes out (while speaking) as a “cognitive need” (this is
a personal opinion) of the communicative act (the multimodal facets of
communication), even though the gesture types and their distribution
along the speech may depend both on the speaker and language.
Gestures have been categorized using several classification
systems (e.g. Efron, 1941; Ekman and Friesen, 1969; McNeill and
Levy, 1982; McNeill, 1992) that mainly differ in the number of enlisted
gesture categories and several theories were advanced to explain
their role in communication. There is considerable body of evidence
supporting the idea that gestures share with speech similar semantic
and pragmatic functions, i.e. neither gestures nor speech alone
have a primary role in the communicative act (Kendon, 1980, 2004;
McNeil, 1992, 2005; De Ruiter, 2000; Goldin-Meadow, 2003; Esposito
and Marinaro, 2007, Esposito and Esposito, 2011). There is also a
large research work investigating gestures in non-human primates
showing that their deployment of hands and body movements is both
flexible 2 and intentional 3 and also for them it emerges as a need of the
communicative act to clearly shape thoughts, intentions and needs.
Nevertheless, in relation to human primates, there are data
suggesting that they are secondary to speech, being of support to the
speaker's effort to encode his/her message (Freedman, 1972; Rimé and
Schiaratura, 1992; Rausher et al., 1996; Krauss et al., 2000; Morsella
and Krauss, 2005a, 2005b).
The idea that gestures support lexical retrievals and that in general
their role in interactive communications is to assist the listener, or the
speaker, or both, appears to be widespread. This is because during
our daily interactions, awareness of the semantic content of our verbal
messages is favored by the continuous auditory feedback. On the
contrary, our gesticulation, posture and facial expressions are visible
2 Non-human primates change their gestural actions in order to clarify the meaning
of their messages when misunderstood, and flexibly create new gestural signals
avoiding repetitions of behaviors that fail the communicative goal (Cartmill and
Byrne, 2007; Cartmill et al., 2012).
3 Non-human primates mainly exploit silent visual gestures when the interactant can
easily see and is attentive to them, while tactile gestures are often used when this
is not the case (Genty and Byrne, 2010; Genty et al., 2009).