1. See Edward T. Heyn, “Berlin’s Wonderful Horse,” New York Times, September 4, 1904; “ ‘Clever Hans’ Again,” New York Times, October 2, 1904; “A Horse—and the Wise Men,” New York Times, July 23, 1911; and “Can Horses Think? Learned Commission Says ‘Perhaps,’” New York Times, August 31, 1913.
2. B. Hare et al., “The Domestication of Social Cognition in Dogs,” Science 298 (November 22, 2002): 1634–36; Brian Hare and Michael Tomasello, “Human-like Social Skills in Dogs?” Trends in Cognitive Sciences, 9, no. 9 (2005): 440–44; and A. Miklosi et al., “Comparative Social Cognition: What Can Dogs Teach Us?” Animal Behavior 67 (2004): 995–1004.
3. Monique A. R. Udell et al., “Wolves Outperform Dogs in Following Human Social Cues,” Animal Behavior 76 (2008): 1767–73.
4. Jonathan J. Cooper et al., “Clever Hounds: Social Cognition in the Domestic Dog (Canis familiaris),” Applied Animal Behavioral Science 81 (2003): 229–44, and A. Whiten and R. W. Byrne, “Tactical Deception in Primates,” Behavioral and Brain Sciences 11 (2004): 233–73.
5. Hare, “The Domestication of Social Cognition in Dogs,” 1634, and E. B. Ginsburg and L. Hiestand, “Humanity’s Best Friend: The Origins of Our Inevitable Bond with Dogs,” in The Inevitable Bond: Examining Scientist-Animal Interactions, ed. H. Davis and D. Balfour (Cambridge: Cambridge University Press, 1991), 93–108.
6. Robert Rosenthal and Kermit L. Fode, “The Effect of Experimenter Bias on the Performance of the Albino Rat,” Behavioral Science 8, no. 3 (1963): 183–89; see also Robert Rosenthal and Lenore Jacobson, Pygmalion in the Classroom: Teacher Expectation and Pupils’ Intellectual Development (New York: Holt, Rinehart, and Winston, 1968), 37–38.
7. L. H. Ingraham and G. M. Harrington, “Psychology of the Scientist: XVI. Experience of E as a Variable in Reducing Experimenter Bias,” Psychological Reports 19 (1966): 455–461.
8. Robert Rosenthal and Kermit L. Fode, “Psychology of the Scientist: V. Three Experiments in Experimenter Bias,” Psychological Reports 12 (April 1963): 491–511.
9. Rosenthal and Jacobson, Pygmalion in the Classroom, 29.
10. Ibid.
11. Robert Rosenthal and Lenore Jacobson, “Teacher’s Expectancies: Determinants of Pupil’s IQ Gains,” Psychological Reports 19 (August 1966): 115–18.
12. Simon E. Fischer and Gary F. Marcus, “The Eloquent Ape: Genes, Brains and the Evolution of Language,” Nature Reviews Genetics 7 (January 2006): 9–20.
13. L. A. Petitto and P. F. Marentette, “Babbling in the Manual Mode: Evidence for the Ontology of Language,” Science 251 (1991): 1493–96, and S. Goldin-Meadow and C. Mylander, “Spontaneous Sign Systems Created by Deaf Children in Two Cultures,” Nature 391 (1998): 279–81.
14. Charles Darwin, The Autobiography of Charles Darwin (1887, repr. New York: Norton, 1969), 141; see also Paul Ekman, “Introduction,” in Emotions Inside Out: 130 Years After Darwin’s “The Expression of the Emotions in Man and Animals” (New York: Annals of the N.Y. Academy of Science, 2003), 1–6.
15. For example, J. Bulwer, Chirologia; or, The Natural Language of the Hand (London: Harper, 1644); C. Bell, The Anatomy and Philosophy of Expression as Connected with the Fine Arts (London: George Bell, 1806); and G. B. Duchenne de Boulogne, Mecanismes de la Physionomie Humaine, ou Analyse Electrophysiologique de l’Expression des Passions (Paris: Bailliere, 1862).
16. Peter O. Gray, Psychology (New York: Worth, 2007), 74–75.
17. Antonio Damasio, Descartes’ Error: Emotion, Reason, and the Human Brain (New York: Putnam, 1994), 141–42.
18. Quoted in Mark G. Frank et al., “Behavioral Markers and Recognizability of the Smile of Enjoyment,” Journal of Personality and Social Psychology 64, no. 1 (1993): 87.
19. Ibid., 83–93.
20. Charles Darwin, The Expression of the Emotions in Man and Animals (1872; repr. New York: D. Appleton, 1886), 15–17.
21. James A. Russell, “Is There Universal Recognition of Emotion from Facial Expression? A Review of the Cross-Cultural Studies,” Psychological Bulletin 115, no. 1 (1994): 102–41.
22. See Ekman’s Afterword in Charles Darwin, The Expression of the Emotions in Man and Animals (1872; repr. Oxford: Oxford University Press, 1998), 363–93.
23. Paul Ekman and Wallace V. Friesen, “Constants Across Cultures in the Face and Emotion,” Journal of Personality and Social Psychology 17, no. 2 (1971): 124–29.
24. Paul Ekman, “Facial Expressions of Emotion: An Old Controversy and New Findings,” Philosophical Transactions of the Royal Society of London B 335 (1992): 63–69. See also Rachel E. Jack et al., “Cultural Confusions Show That Facial Expressions Are Not Universal,” Current Biology 19 (September 29, 2009): 1543–48. That study found results that, despite the paper’s title, were “consistent with previous observations,” although East Asians confused fear and disgust with surprise and anger in Western faces more often than Westerners themselves did.
25. Edward Z. Tronick, “Emotions and Emotional Communication in Infants,” American Psychologist 44, no. 2 (February 1989): 112–19.
26. Dario Galati et al., “Voluntary Facial Expression of Emotion: Comparing Congenitally Blind with Normally Sighted Encoders,” Journal of Personality and Social Psychology 73, no. 6 (1997): 1363– 79.
27. Gary Alan Fine et al., “Couple Tie-Signs and Interpersonal Threat: A Field Experiment,” Social Psychology Quarterly 47, no. 3 (1984): 282–86.
28. Hans Kummer, Primate Societies (Chicago: Aldine-Atherton, 1971).
29. David Andrew Puts et al., “Dominance and the Evolution of Sexual Dimorphism in Human Voice Pitch,” Evolution and Human Behavior 27 (2006): 283–96; Joseph Henrich and Francisco J. Gil- White, “The Evolution of Prestige: Freely Conferred Deference as a Mechanism for Enhancing the Benefits of Cultural Transmission,” Evolution and Human Behavior 22 (2001): 165–96.
30. Allan Mazur et al., “Physiological Aspects of Communication via Mutual Gaze,” American Journal of Sociology 86, no. 1 (1980): 50–74.
31. John F. Dovidio and Steve L. Ellyson, “Decoding Visual Dominance: Attributions of Power Based on Relative Percentages of Looking While Speaking and Looking While Listening,” Social Psychology Quarterly 45, no. 2 (1982): 106–13.
32. R. V. Exline et al., “Visual Behavior as an Aspect of Power Role Relationships,” in Advances in the Study of Communication and Affect, vol. 2, ed. P. Pliner et al. (New York: Plenum, 1975), 21– 52.
33. R. V. Exline et al., “Visual Dominance Behavior in Female Dyads: Situational and Personality Factors,” Social Psychology Quarterly 43, no. 3 (1980): 328–36.
34. John F. Dovidio et al., “The Relationship of Social Power to Visual Displays of Dominance Between Men and Women,” Journal of Personality and Social Psychology 54, no. 2 (1988): 233–42.
35. S. Duncan and D. W. Fiske, Face-to-Face Interaction: Research, Methods, and Theory (Hillsdale, NJ: Erlbaum, 1977), and N. Capella, “”Controlling the Floor in Conversation,” in Multichannel Integrations of Nonverbal Behavior, ed. A. W. Siegman and S. Feldstein (Hillsdale, NJ: Erlbaum, 1985), 69–103.
36. A. Atkinson et al., “Emotion Perception from Dynamic and Static Body Expressions in Point-Light and Full-Light Displays,” Perception 33 (2004): 717–46; “Perception of Emotion from Dynamic Point-Light Displays Represented in Dance,” Perception 25 (1996): 727—38; James E. Cutting and Lynn T. Kozlowski, “Recognizing Friends by Their Walk: Gait Perception Without Familiarity Cues,” Bulletin of the Psychonomic Society 9, no. 5 (1977): 353–56; and James E. Cutting and
