How do ordered questions bias eyewitnesses?

Background: Suggestive techniques can distort eyewitness memory (Wells & Loftus, 2003, Eyewitness memory for people and events. In A. M. Goldstein (Ed.), Handbook of psychology: Forensic Psychology, Vol. 11 (pp. 149–160). Hoboken, NY: John Wiley & Sons Inc). Recently, we found that suggestion is unnecessary: Simply reversing the arrangement of questions put to eyewitnesses changed what they believed (Michael & Garry, 2016, Ordered questions bias eyewitnesses and jurors. Psychonomic Bulletin & Review, 23, 601–608. doi:10.3758/s13423-015-0933-1). But why? One explanation might be that early questions set an anchor that eyewitnesses then adjust away from insufficiently. Methods: We tracked how eyewitness beliefs changed over the course of questioning. We then investigated the influence of people’s need to engage in and enjoy effortful cognition. This factor, “Need for Cognition,” (NFC) affects the degree to which people adjust (Cacioppo, Petty, & Feng Kao, 1984, The efficient assessment of need for cognition. Journal of Personality Assessment, 48, 306–307. doi:10.1207/s15327752jpa4803_13; Epley & Gilovich, 2006, The anchoring-and-adjustment heuristic: Why the adjustments are insufficient. Psychological Science, 17, 311–318. doi:10.1111/j.1467-9280.2006.01704.x). Results: In our first two experiments we found results consistent with an anchoring-and-adjustment account. But in Experiments 3 and 4 we found that NFC provided only partial support for that account. Conclusions: Taken together, these findings have implications for understanding how people form beliefs about the accuracy of their memory.