  Multimodal corpora have become an essential language resource for language
science and grounded natural language processing (NLP) systems due to the
growing need to understand and interpret human communication across various
channels. In this paper, we first present our efforts in building the first
Multimodal Corpus for Languages in Taiwan (MultiMoco). Based on the corpus, we
conduct a case study investigating the Lexical Retrieval Hypothesis (LRH),
specifically examining whether the hand gestures co-occurring with speech
constants facilitate lexical retrieval or serve other discourse functions. With
detailed annotations on eight parliamentary interpellations in Taiwan Mandarin,
we explore the co-occurrence between speech constants and non-verbal features
(i.e., head movement, face movement, hand gesture, and function of hand
gesture). Our findings suggest that while hand gestures do serve as
facilitators for lexical retrieval in some cases, they also serve the purpose
of information emphasis. This study highlights the potential of the MultiMoco
Corpus to provide an important resource for in-depth analysis and further
research in multimodal communication studies.
