Professor Stephen Ceci had an idea.  He had taught the same course in human development for 20 years. He wondered whether he could influence the reviews of his class by tweaking one small aspect of his class.  

   In the spring semester, he painstakingly copied all aspects of his class from the fall semester.  He recorded audio of himself giving lectures during the semester. He kept the same book, exams, materials, syllabus, grading policies, office hours, and even memorized his lectures from the fall semester.

He made only one small change to his class, but this change resulted in his student ratings going up in every single category.   He was perceived as more: enthusiastic, knowledgable, tolerant of others’ views, organized and accessible.  “Course goals, expectations, and grading policy were more clearly stated and that the grading was more fair.  They even rated the identical textbook more positively in the spring.”  His average rating -on a 5 point scale- increased from a 3.5 to a 4.

Two independent coders listened to multiple lectures that were randomly selected from both semesters.  They found that the ideas communicated in fall and spring were 100 percent in agreement.

What did Professor Ceci do?

 He utilized the fact that within seconds the impression of you is imprinted in people’s brains and it takes a lot to change that impression.

The Science of Trust

If you want students to learn from you, you have to first learn how you are perceived. The unfortunate truth for teachers, and what they don’t tell you in education classes, is that people decide first what they think about you before they decide what they think about your message.

A 2015 analysis of the popular TED Talks, had 760 volunteers rate hundreds of hours of TED talks looking for patterns.   The biggest find of the study was that there was no difference in ratings between people who watched talks on mute and people who watched talks with sound.  People simply liked speakers just as much on mute as they did when they could hear them. But why?  As it turns out, this holds true with teachers as well.

Thin Slicing

Science has a name for the snap judgments that our brains make when they first interact with someone.  The term is thin-slicing, which was developed by Nalini Ambady at Tufts University.  She videotaped over a dozen teachers teaching a lesson.  She then cut the video clip into 30- second bites.  This clip was shown to people and she asked to judge the effectiveness of the teacher.  She then compared the participants’ responses to what the actual students indicated in their end of semester evaluations.  Astonishingly, the viewers accurately evaluated the effectiveness of these teachers from the 30-second clip!

However, Ambady didn’t stop there.  She then continued to cut the clips to fifteen seconds and then to only six seconds.  Each time the viewers of the clips rated the effectiveness of the teachers almost as accurately!

In the next installment, we will learn the four factors of Teacher Credibility and what Professor Ceci did to harness those factors.


What do you think made the difference in these Thin Slice video clips?


  • Hertenstein, M. (2013). The tell: The little clues that reveal big truths about who we are. Basic Books.

  • Barker, E. (2014, May 23). The One Simple Thing That Can Make You Much More Impressive. Retrieved February 25, 2015, from http://time.com/109342/the-one-simple-thing-that-can-make-you-much-more-impressive/
    Neffinger, John, and Matthew Kohut. Compelling People: The Hidden Qualities That Make Us Influential. Plume, 2014. Print.

  • Edwards, V. (2015, March 13). 5 Secrets of a Successful TED Talk. Retrieved April 4, 2015, from http://www.huffingtonpost.com/vanessa-van-edwards/5-secrets-of-a-successful_b_6887472.html

  • Ambady, N., & Rosenthal, R. (n.d.). Half A Minute: Predicting Teacher Evaluations From Thin Slices Of Nonverbal Behavior And Physical Attractiveness. Journal of Personality and Social Psychology, 431-441.

  • Hattie, J. (2012). Visible learning for teachers: Maximizing impact on learning (p. 272). London: Routledge.