Work in this area is new and here we suggest elements important to appearance and point to literature found in our search. Research is more developed for "color" and "voice."
Robot color
Eye color
"Skin" tone
Clothing (Jung et al., 2016; Wang et al., 2021)
Hair style (Eyssel and Hegel, 2012)
Lips shape (Eyssel and Hegel, 2012)
Physique, anatomy (Wang et al., 2021)
Size (height and weight) (Small is non-threatening, (Obaid et al., 2016)