Experimenter Bias in Hypnotist Performance

http://www.paradigm-sys.com/cttart/sci-docs/ctt64-ebihp.html

In this study on experimenter bias, how were judges able to tell under which condition the subjects were tested by listening to the performances of the experimenters?

Whitehouse, W. G., Orne, E. C., & Dinges, D. F. (2002). Demand Characteristics: Toward an Understanding of Their Meaning and Application in Clinical Practice, Prevention & Treatment, 5.

http://www.journals.apa.org/prevention/volume5/pre0050034i.html

In this article, the authors consider the role of demand characteristics in psychotherapy. They begin by addressing how contemporary researchers in the social and behavioral sciences tend to regard the effects yielded by situational demand characteristics. What are their thoughts on this matter?