The recent discovery of three women in Cleveland, Ohio, who had been abducted for such an extended period, has rekindled hopes that others long-missing could still be found. The search for Madeleine McCann appears to have been re-invigorated, coinciding with the recent publication of an 'age-progressed' photograph.
But new data from a recent series of psychology experiments, investigating how people recognize missing children, are alarming. The results suggest that the very techniques police forces around the world are currently using, may actually be making it harder to recover missing children.
When a child has gone missing for an extended period, predicting accurately current appearance seems imperative. This is currently accomplished via forensic techniques known as 'age progression,' in which an old photograph of the missing person is used to predict how the child would look now, using computer modelling.
In the USA it is claimed that age progression has helped to recover one of out every seven children reported missing to the National Center for Missing and Exploited Children. In almost every case in which age progression is used, it's also claimed new leads are generated.
Linked to the release of the age-progressed image of Madeleine McCann, the media have widely reported that UK detectives reviewing the case of her 2007 disappearance have identified "a number of persons of interest".
Although increasingly widely used, and offering much hope to distressed relatives and searchers, whether the technique actually aids recognition, has not been properly scientifically tested.
But psychologists Steve Charman and Rolando Carol, from Florida International University, have recently claimed in a new study, that age-progressed images might even harm recognition.
This has serious and profound implications for the current search strategy for Madeleine McCann, and others, particularly given how much publicity current age-progressed images have received all around the world.
In this research, participants are presented with either an outdated image of a child, an age-progressed image of a child, or both images, and then are exposed to a series of faces of young adults, and then asked to indicate whether any of them are the 'target' or missing child.
Charman and Carol found in their study that the addition of an age-progressed image significantly harmed recognition of the child, and significantly inflated false recognition.
The current study entitled 'Age-progressed images may harm recognition of missing children by increasing the number of plausible targets' found that the age-progressed images were not just simply decreasing the likelihood of recognizing anyone, but they seemed to be systematically leading people away from recognizing the target (and toward mistakenly 'recognizing' non-targets).
Charman and Carol's recent finding is absolutely crucial to the field of missing children investigation, as this remains one of the only proper investigations of this popular technique, and it indicates age-progressed images may actually harm ability to recognize a target.
Charman and Carol acknowledge this result is intriguing and counterintuitive: If the age-progressed image was a poor representation of the target, participants who viewed both an outdated and an age-progressed image could have simply ignored it and relied solely upon the outdated image. But they clearly did not: In fact, they performed worse than participants who viewed only the outdated image.
The detrimental effect of age-progressed images is most probably partly a psychological effect: The addition of an age-progressed image somehow changes observers' decision-making strategies, and does so in a profoundly unhelpful way.
Charman and Carol conducted further studies to investigate the precise mechanism by which age-progressed images seem to impede recognition of missing children. Adding an age-progressed image to an outdated image appears to effectively create a second target face that people use when looking for the target. But the age-progressed image is not a very accurate representation of what the actual missing child currently looks like. Therefore, the age-progressed image increases the number of competing non-target faces that are seen as possibly being the target.
Because more faces are now competing with the target's face for recognition, this results in lower recognition of the missing child, and inflated mistaken recognition of other faces.
Charman and Carol point out there are two possible negative costs associated with a recognition error produced by age-progressed images in the real world: An observer may mistakenly 'recognize' a non-target (a false alarm) or may fail to recognize an actual target (a miss). But these errors are not equal: The failure to recognize a missing child is much more serious than mistakenly 'recognizing' someone.
Consequently, an age-progression procedure that increased hits would be beneﬁcial, even if it led to an increase in false alarms. The problem is that these new results suggest that age-progressed images seem to actually reduce the likelihood of correctly recognizing a missing child.
In other words, age-progressed images were not simply useless; they were in fact worse than useless, leading people away from the actual 'missing child'.
If observers behaved logically, then adding an age-progressed image to an outdated image should lead them to narrow in on a target. But, in contrast, it actually increases the number of plausible targets.
Basically people do not respond logically to age-progressed images.
Their data, published in the 'Journal of Applied Research in Memory and Cognition' suggests that instead of realizing that the target must be a plausible match to both the outdated image and the age-progressed image (or, if the age-progressed image is perceived to be completely worthless, to only the outdated image), people seem to respond to age-progressed images by reasoning that the target must match either the outdated image or the age-progressed image, but not necessarily both.
Age-progression techniques are problematic not only because the algorithms of those techniques by which the photo is generated could be ﬂawed, but also because observers are using information derived from age-progressed images incorrectly.
Charman and Carol conclude their study by pointing out the anecdotal evidence from The National Center for Missing and Exploited Children, which claims: "In virtually every case the production and distribution of an updated [i.e., age-progressed] image stimulates new leads" may not in fact be the good news it is touted to be.
Any purported increase in leads may just tend to be false recognitions of non-targets. Given the recent much trumpeted 'good news' suggesting the possible generation of new leads over Madeleine McCann, there is an ominous possibility suggested by this new research, that the hunt is heading in the wrong direction.
Follow Dr Raj Persaud on Twitter: www.twitter.com/@DrRajPersaud