Kraus and Keltner videotaped more than 100 college students as they got to know a complete stranger in 5-minute, one-on-one interviews. The researchers looked for "disengagement cues" (doodling or fidgeting) and "engagement cues" (eye contact, laughing, and raised eyebrows). During 60-second clips, Kraus and Keltner noted that students with parents with a higher socioeconomic status (SES) tended to be ruder in conversation, doodling, fidgeting, and periodically grooming themselves for an average of 2 seconds. Students with parents with lower SES—below the state's median income level—barely fidgeted, and tended to smile, raise their eyebrows, and were generally more engaged and polite in conversation. Furthermore, a separate group of volunteers were shown the 60 second clips, and they were often able to correctly guess the SES background of the students based on body language.