A deeply flawed study
The study is fundamentally flawed for several reasons:
1. The relative quality of the robots was not taken into account in any way. Especially the "black" robot (Bina48) transcends "uncanny valley" and is deep into "creepy canyon" due to uncoordinated eye movements (the lazy eye was pointed out by several commenters), jerky motion control and an computer generated voice reading inane comments, which come across heavily scripted.
2. There is no indication in the study of how "racial identities" were assigned to the robots. Again, how is Bina48 "black"?
3. The sample-size is quite small N (N=90 (Bina), 162 (Nadine), 76 (YangYang)) and how comments were interpretated as "dehumanizing" remains nebulous to put it mildly.
The reporting here, is a disappointment coming from ElReg. I expected better than that.