Funding for this research was provided by:
Universidade de Macau (MYRG2019-00082-FHS, MYRG2018-00081-FHS)
Fundo para o Desenvolvimento das Ciências e da Tecnologia (FDCT 025/2015/A1, FDCT 0011/2018/A1)
Received: 27 July 2020
Accepted: 13 November 2020
First Online: 1 December 2020
Consent for publication
: The facial expressions were chosen from a public dataset, and the facial pictures presented in Fig. InternalRef removed were consented to use in this publication.
: The authors declare that they have no competing interests.