One can also assume that, at the highest level, the user simply needs to know how much trust to invest in the agent. Trust, in this situation, is the relative ability level which the human user attributes to a certain software entity. In the short term, especially during the initial exposures of the user to the agent, the interface will have to provide some other information to aid the user in appraising the agent. The reasoning behind this suggestion is that the anthropomorphic representation allows for a rich set of easily identifiable behaviors and for social interaction. If anything, these representations may make the agent seem more intelligent, capable of a higher level of agency, and more trustworthy than it actually is.
Empirical data are necessary to make any conclusive statements.
Half of the subjects were male. The set included Chernoff faces, with both positive and negative facial expressions, and stylized facial caricatures. It included very high resolution human forms in two and three dimensions and in wire frame. Some of the faces exhibited random eye blinking. The set also included a variety of non-facial forms of equal geometric complexity to balance the experiment.