Changes in attention and visual perception are correlated with aging: Older people find it harder to see the wood for the trees

ScienceDaily (July 25, 2011) — When looking at a picture of many trees, young people will tend to say: "This is a forest." However, the older we get, the more likely we are to notice a single tree before seeing the forest. This suggests that the speed at which the brain processes the bigger picture is slower in older people. In a new study published in the July-August issue of Elsevier´s Cortex, researchers have found that these age-related changes are correlated with a specific aspect of visual perception, known as Gestalt perception.See Also:Plants & AnimalsTreesMiceNatureEarth & ClimateForestGlobal WarmingClimateStrange ScienceReferenceVisual acuityColor visionThe evolution of human intelligenceMirror test

Markus Staudinger, together with Gereon R. Fink, Clare E. Mackey, and Silke Lux, investigated the brain's ability to focus on the local and global aspects of visual stimuli, in a group of young and elderly healthy subjects. They also studied how this ability is related to Gestalt perception, which is the mind's tendency to perceive many similar smaller objects as being part of a bigger entity. As expected, older people found it more difficult to concentrate on the global picture, but they also had trouble with the Gestalt principle of Good Continuation -- the mind's preference for continuous shapes.

Participants in the study were shown groups of letters which were arranged in a pattern so that they formed a larger letter (see below), and asked whether a letter appeared on the local or global level. Importantly, the number of small letters forming the pattern was then varied. Usually, the smaller the letters are in the pattern, the easier it is to perceive the larger letter, and this was indeed true for the younger participants in the study. However, varying the number or letters did not help the older people, who remained slower to notice the global figure.

These findings provide the first evidence that changes in attention -- meaning, the ability to concentrate on one thing, while ignoring others -- and in Gestalt perception are correlated to healthy aging. More generally, they show that there may be age-related changes in different cognitive domains which interact. Furthermore, the results help us understand which specific aspects of visual perception become impaired in healthy aging.

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Smartphone making your eyes tired? Images placed in front of the screen increase visual discomfort

ScienceDaily (July 22, 2011) — Several reports indicate that prolonged viewing of mobile devices and other stereo 3D devices leads to visual discomfort, fatigue and even headaches. According to a new Journal of Vision study, the root cause may be the demand on our eyes to focus on the screen and simultaneously adjust to the distance of the content.See Also:Health & MedicineEye CarePain ControlMatter & EnergyOpticsEngineeringComputers & MathMobile ComputingComputer ProgrammingReferenceSound effectComputer animationEye examinationHyperopia

Scientifically referred to as vergence-accommodation, this conflict and its effect on viewers of stereo 3D displays are detailed in a recent Journal of Vision article, The Zone of Comfort: Predicting Visual Discomfort with Stereo Displays.

"When watching stereo 3D displays, the eyes must focus -- that is, accommodate -- to the distance of the screen because that's where the light comes from. At the same time, the eyes must converge to the distance of the stereo content, which may be in front of or behind the screen," explains author Martin S. Banks, professor of optometry and vision science, University of California, Berkeley.

Through a series of experiments on 24 adults, the research team observed the interaction between the viewing distance and the direction of the conflict, examining whether placing the content in front of or behind the screen affects viewer discomfort. The results demonstrated that with devices like mobile phones and desktop displays that are viewed at a short distance, stereo content placed in front of the screen -- appearing closer to the viewer and into the space of viewer's room -- was less comfortable than content placed behind the screen. Conversely, when viewing at a longer distance such as a movie theater screen, stereo content placed behind the screen -- appearing as though the viewer is looking through a window scene behind the screen -- was less comfortable.

"Discomfort associated with viewing Stereo 3D is a major problem that may limit the use of technology," says Banks. "We hope that our findings will inspire more research in this area."

The team of investigators suggests future studies focus on a larger sample in order to develop population-based statistics that include children. With the explosion of stereo 3D imagery in entertainment, communication and medical technology, the authors also propose guidelines be established for the range of disparities presented on such displays and the positioning of viewers relative to the display.

"This is an area of research where basic science meets application and we hope that the science can proceed quickly enough to keep up with the increasingly widespread use of the technology," adds Banks.

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