It’s your choice! – Or is it really?

Merckelbach, Jelicic, and Pieters (2011b, Experiment 2) investigated choice blindness for intensity ratings of one’s own psychological symptoms. Their participants had to rate the frequency with which they experienced 90 common symptoms (e.g., anxiety, lack of concentration, stress, headaches etc.) on a 5-point Likert scale. Prior to a follow-up interview, the researchers inflated ratings for two symptoms by two points. For example, when participants had rated their feelings of shyness, as 2 (i.e.,occasionally), it was changed to 4 (i.e., all the time). This time, more than half (57%) of the 28 participants were blind to the symptom rating escalation and accepted it as their own symptom intensity rating. This demonstrates that blindness is not limited to recent preference selections (Hall et al., 2010; Johansson et al. 2005), but can also occur for intensity and frequency ratings that rely on long-term episodic memory.

Inspired by these findings, Sauerland, Schell, Collaris, Reimer, Schneider, and Merckelbach (2012) tested blindness for one’s own history of norm-violating behaviors. Specifically, they explored whether choice blindness might be relevant to suspects’  false confessions. Participants were presented with an 18-item questionnaire about their history of norm violation which asked them to rate how often they had displayed each behavior on a 4-point Likert scale. Participants were later interviewed about four of those items, two of which had covertly been manipulated. For example, the response to the item “I have never committed small-scale shop lifting” was changed from never to sometimes. As expected, a substantial proportion (25%) of participants failed to notice changes of their own ratings. Importantly, detection varied as a function of the interval between completing the questionnaire and being interviewed about the manipulated outcome. Participants in Experiment 1 who were presented with the manipulated outcome after 10 minutes were more likely to notice the change in their response compared to Experiment 2 participants who were presented with the manipulation after a week (75% and 55%, respectively). Thus, the longer interval resulted in a decrease of the detection rate.

Together, these studies suggest that choice blindness can occur in a wide variety of situations. Although the mechanisms behind these effects remain unclear, we believe ambiguity may play a key role. It may be inherent to the task, as it is for example with evaluative choices (Hall et al., 2011; Johansson et al, 2005) which are less clear cut than tasks involving an objectively correct or incorrect outcome. In studies involving self-reported ratings, the items being measured are not easily defined (such as the intensity of one’s symptoms), making changes difficult to detect. Finally, ambiguity can also be introduced by increasing the time between the decision and the presentation of the chosen item.

Choice Blindness in Eyewitness Settings

With these studies in mind, we wondered what the implications of choice blindness for eyewitness settings could be. After identifying a suspect from a  lineup, eyewitnesses are frequently required to identify him/her again inside the courtroom. Consider a situation where the  lineup administrator - intentionally or unintentionally - writes down a choice other than the one made by the witness. Given the current evidence on choice blindness, one might worry that a considerable proportion of eyewitnesses may not notice that change. This, of course, could have devastating consequences for the defendant.

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