MELBOURNE: Lack of proper sleep can impact the accuracy of face identification, researchers have found, suggesting that the crucial “passport task” by officers can be affected by poor sleep.
It is often necessary to identify unfamiliar people by comparing face images: for example a CCTV image to a mugshot, or a passport photograph to a traveller.
Researchers from the University of New South Wales (UNSW) in Australia and the University of Glasgow in the UK, found that accuracy of these decisions is impaired by poor sleep.
However, the study also found that poor sleepers were just as confident in their decisions, highlighting possible implications for security and policing.
Participants were asked to decide whether two images, presented on a computer monitor at the same time, pictured the same person or two different people.
The researchers set the task to differ from the face recognition tasks most of us encounter in our daily lives in two important ways: firstly, the people pictured in the images are unfamiliar.
Secondly, the task did not involve memory, because the images appear on the screen at the same time.
Researchers said that while most people would typically expect to perform well on these tasks, many are surprised at how many errors they make.
Previous studies have shown impaired memory for faces following restricted sleep. However, until now it was not known whether lack of sleep impairs performance on face identification tasks that do not rely on recognition memory.
“We found that poor sleep in the three days leading up to the test was associated with poorer performance on the face matching test. In a separate experiment, we also found that participants with insomnia were poorer on the task,” said Louise Beattie, from the the University of Glasgow.
“Sleep disruption is common in the general population, and especially so among night-shift workers,” Beattie said.
“Here we show for the first time that performance in a crucial “passport task” is affected by poor sleep, and our research has important implications for those working in security or forensic settings,” she added.
“This adds to the literature showing poor sleep and shift work to be associated with a range of adverse health, cognitive and emotional effects,” she said.
The researchers said that poor sleep was not only associated with poorer performance, but also with higher levels of confidence in errors.
“In modern society it is often necessary to identify unfamiliar people by comparing face images. In this study we show that the accuracy of these decisions is impaired in poor sleepers,” said David White, from UNSW.
“Worryingly, although poorer sleep was associated with reduced accuracy, poor sleepers were not less confident in their responses. This has important implications for security and policing, where shift work is common,” said White.
The study was published in the journal Royal Society Open Science.
Face transplantation can dramatically enhance a patient’s quality of life after severe facial trauma, but lack of attention to eyelid function and vision can leave patients with impaired vision, corneal exposure, eyelid retraction that occurs when the upper or lower eyelid pulls away from the eyeball, and other eyelid-related complications. A new retrospective study led by researchers at NYU Langone Medical Center makes the case for careful blink assessment in planning facial transplant procedures, as well as during and after transplant, and post-transplant revision surgeries. Their work appears online in the January 2015 issue of Plastic and Reconstructive Surgery.
The research team, led by senior author Eduardo D. Rodriguez, MD, DDS, the Helen L. Kimmel professor and chair of the Department of Plastic Surgery at NYU Langone, and Director of its Institute of Reconstructive Plastic Surgery, underscore the importance of being extremely methodical in assessing eyelid function because loss of the protective blink reflex can not only compromise vision, but lead to blindness over time. Blinking is a complex facial function that has not been carefully addressed in the facial transplantation literature before this manuscript.
“There is no guarantee that the eyelids will function normally after transplantation,” explains Dr. Rodriguez. “Careful and methodical preparation prior to facial transplantation, and attentiveness to post-surgical eyelid function, is essential to preserving vision in these cases.”
In the paper, “Eyelid Transplantation: Lessons from a Total Face Transplant and the Importance of Blink,” Dr. Rodriguez and his co-investigators report on a patient with a severe injury to the central and lower face caused by a gunshot injury. They describe what procedures they used to preserve and restore blinking function, which can be damaged from the trauma and during surgery. Nerve injury also can occur with tissue handling and during dissection of vital structures.
This particular patient, Richard Lee Norris of Virginia, whose case has been well documented in professional literature and by media outlets worldwide, had one of the most extensive and comprehensive face transplants reported to date, involving total face, double jaw, and tongue transplantation. Slow-motion video analysis of blinking, especially involuntary or “reflex” blinking, was done before face transplantation and up to several months after the surgery.
Visual acuity was evaluated prior to transplantation, eye movement was also assessed preoperatively, and again, six months following transplantation. Evaluation of the eye socket in surgical planning and postoperatively was also performed.
Before the first surgery, the patient had complete eyelid closure in both eyes, equivalent to 100 percent normal voluntary blinking function, but involuntary blinking was impaired in the left eye with diminution on the right (40 percent) following the initial injury. After the surgery, reflex blinking of the right eye improved to 70 percent. The left eye fared well as reflex blink was preserved to the same degree from before the transplant (90 percent). Six months after transplantation, the patient had normal visual acuity and eye movement in both eyes. Involuntary blinking improved to 90 percent in the right eye and 100 percent in the left eye.
“This is the first article addressing blinking in the facial transplant setting,” commented Dr. Rodriguez. “We have to work carefully to preserve the underlying muscle, the eyelids structures and their innervation. Blinking may seem like a simple, automatic function to many people. However, if you can’t blink, your corneas are susceptible to the extremes of weather and exposure of the corneas while you sleep due to incomplete closure. This ultimately results in painful corneal exposure and potential scarring over part of the pupil which will ultimately impair vision.”
The research team hopes that this retrospective study stimulates more meticulous attention to the eye in facial transplantation.
The above post is reprinted from materials provided by NYU Langone Medical Center / New York University School of Medicine. Note: Content may be edited for style and length.