Why do some spoken utterances involve gestures whereas others do not? -- Activation of visuo-spatial and motor imagery -- Problems in lexical access and in conceptualization -- The Lexical Retrieval Hypothesis -- The Information Packaging Hypothesis -- Performing gestures or not: effects on speech production -- How do spoken and gestural production cooperate? -- Physical characteristics of oral and manual movements -- Temporal relationships between gestures and speech -- Conclusions: cooperative or competitive relationships? -- Summary -- Research questions -- Notes -- References -- 5 The impact of gestures on speech comprehension -- Is message comprehension influenced by the gestures of the speaker? -- A first provocative answer: gestures have vague meaning and convey little information -- Alternative no. 1: gestures mainly convey information of the visuo-spatial or motor kind -- Alternative no. 2: useful information conveyed by gesture is not redundant with discourse content -- How is visual and auditory information integrated in verbal comprehension using electrophysiological approaches? -- Conclusions -- Summary -- Research questions -- Notes -- References -- 6 Evolution and neuropsychology of gestures -- Does human speech stem from manual skills? -- Do gestures and speech involve the same brain regions? -- Manual preferences in speech-related gestures -- Gesture use by persons suffering from brain lesions -- Neuroimagery of gestural communication -- Conclusions -- Summary -- Research questions -- Notes -- References -- 7 The development of gestural communication -- How do babies learn to read minds and to communicate their intentions? -- What is the role of gestures in language acquisition? -- The pre-linguistic period -- The motor stereotypies -- Daily life routines -- Gestural references and first word productions -- Symbol use