This book includes a selection papers describing the latest advances and discoveries in the field of human-computer interactions, which were presented at the 6th International Conference on Man-Machine Interactions, ICMMI 2019, held in Cracow, Poland, in October 2019. Human-computer interaction is a multidisciplinary field concerned with the design of computer technology and, in particular, the interaction between humans (the users) and computers. Over recent decades, this field has expanded from its initial focus on individual and generic user behavior to the widest possible spectrum of human experiences and activities. The book features papers covering a variety of topics, which are divided into five sections: 'human-computer interfaces,' 'artificial intelligence and knowledge discovery,' 'pattern recognition,' 'bio-data and bio-signal analysis,' and 'algorithms, optimization and signal processing.' Presenting the latest research in the field, this book provides a valuable reference resource for academics, industry practitioners and students.