What if you saw something that rocked your world ... and you didn't notice?

ResearchBlogging.orgIf you're a regular reader of Cognitive Daily, you're relatively accustomed to seeing surprising things. Indeed, it's gotten to the point where you might even expect it. You've seen optical illusions and videos that baffle the imagination. Yet most participants in psychology research studies aren't aware of the many ways the mind can be "tricked." One of the most dramatic tricks, which we've discussed several times, is the phenomenon of Change Blindness. An object can change right before your eyes, and you're likely not to notice. When you're made aware of the change, you find it hard to believe that you could have been so dense -- and you're not alone; nearly everyone falls for it.

In several studies, a student or other unwitting recruit is being interviewed by an actor, who is then substituted for a completely different person, and the recruit is usually unsurprised by the change. But even though we don't overtly notice these major changes, perhaps it still affects us in some unconscious way.

Travis Proulx and Steven Heine had 81 student volunteers fill out a questionnaire about their entertainment preferences. For one group of students, partway through the experiment, when the female experimenter went to retrieve a second questionnaire, she secretly switched with another identically-dressed experimenter, who administered the second portion of the test (here's a video of the swap [2.8 MB]). Another group instead answered questions about their own death, designed to increase their sense of mortality. A final group served as a control, with no experimenter swap or mortality questions.

Finally, all three groups read a scenario about the arrest of a prostitute, and were asked to act as a judge and determine the amount of a punitive bond ranging from $0 to $1000. Did swapping experimenters affect their judgment? Here are the results:


The students (just five of them) who noticed the experimenter swap were excluded from the analysis. As you can see, changing the experimenter resulted in a higher bond than the control group, and the difference was significant. Students who contemplated their deaths also set the bond significantly higher than the control group. Whether you contemplated your own death or saw an implausible (but unnoticed) event, the results were similar: you were more likely to recommend a higher bond for the prostitute.

The students were interviewed after the study and most appeared "genuinely flabbergasted" to learn that an experimenter swap had occurred, yet they still responded differently to the prostitution scenario compared to the control group. Proulx and Heine say these results are similar to other studies where people have been made to feel threatened before making a judgement: when threatened, people are harsher judges of others. The researchers suggest that the students implicitly noticed the change of experimenter, but since this type of a swap is unusual in real life, they never became conscious of it. Because of this implicit detection of an unusual event, the students behaved as if they had been threatened.

Proulx T, & Heine SJ (2008). The case of the transmogrifying experimenter: affirmation of a moral schema following implicit change detection. Psychological science : a journal of the American Psychological Society / APS, 19 (12), 1294-300 PMID: 19121140

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If there is a significant difference between the group with the changing experimenter and the mortality group, wouldn't that mean the implicit detection does NOT induce the same reaction as being threatened?

Did only five students mention the swap on their own initiative, or did the experimenters actually ask something along the lines of "did you notice an unusual change during your interview?" to make the determination. I could see a lot of people noticing the swap but not being confident enough to bring it up, for fear of being considered nuts.

I think the ad is more a case of what could be loosely described as 'tunnel vision' - a mix of concentration on a particular task, and only seeing what you expect to see.

By mrcreosote (not verified) on 01 Dec 2009 #permalink

Regarding change blindness, has anyone seen the movie SUTURE?

By David Group (not verified) on 01 Dec 2009 #permalink

You might want to consider doing a column on prosopagnosia (aka Faceblindness). A faceblind person has normal vision, but does not retain or recognize faces. This condition exists in varying degrees of course. People with severe conditions don't even recognize close family members. People with mild conditions may need to meet someone 10 times before they recognize them.

It would be interesting to know if this experiment weeded out subjects who have faceblindness, since that could be distorting the question of changeblindness.

It would be interesting to record such interactions if the experimenter started out as an attractive young woman but then was swapped to actor Abe Vigoda.