NARRATOR: Hi, again. This video, brought to you by Carie and Amanda, is going to look at the phenomenon of choice blindness through an experiment by Hall and Johansson, performed in 2006. In the first part of the experiment, participants' ability to detect changes in choices they made about the attractiveness of faces was observed. 

First, participants were shown two faces that either shared similar features or appeared very different. Then, participants chose the face they thought was the most attractive. The experimenter handed the chosen picture back to the participant, and in most cases, this picture was actually the one they chose. 

However, in certain trials, the experimenter used sleight of hand to switch the photographs. What's astounding is that no more than 30% of trials where the wrong photograph was given back to the participant were detected as switched. They still didn't pick up on the trick, even though they had to justify their choice. 

What's more is that a debriefing session following the experiment with participants who never noticed the switch occurred confirmed their lack of awareness. When presented with a hypothetical situation where a switch would occur, 84% of them believed that they would notice the change. This is an example of overconfidence. 

The participants' reasoning for choosing each picture was also analyzed during the experiment for both manipulated and non-manipulated trials. Experimenters looked at variables such as level of emotionality and specificity in participants' explanations, and they found that there was no significant difference between the justifications of their true choice and of the opposite choice. They really had no idea that the pictures were switched. 

However, since faces are processed in a unique, holistic way, Hall and Johansson decided to look at choice blindness in a more naturalistic setting as well. During this study participants, in a supermarket were asked to compare two paired varieties of tea and jam. After selecting their favorite combination, they were given the pair again to taste. Similarly to the previous experiment, on some trials, the chosen combination of tea and jam was switched with the alternative. Overall, no more than 33% of changes were detected, and less than 50% of switches were detected when the flavors were radically different-- for example, switching apples and cinnamon jam with grapefruit jam. 

These experiments suggest that choice blindness phenomenon can occur in a variety of situations. However, the reason people seem to forget the choice they made is still unknown. Some theories include that there was a failure to fully encode their specific reasons for making the choice they made, their exact intentions were forgotten between making the choice and being presented with the alternative, they failed to compare pre and post-change information, or reasoning is encoded in a format that is inaccessible to consciousness.