A new study shows that the human visual system can “trick” the brain into making inaccurate assumptions about the size of objects in the world around them.
The research findings could have implications for many aspects of daily life, such as driving, how eyewitness accounts are handled in the criminal justice system, and security issues, such as drone sightings.
The research team from the University of York and Aston University presented the participants with images of full-scale railway scenes, which had the top and bottom parts of the image blurred, as well as images of small railway models, which were not blurred.
Participants were asked to compare each image and decide which is a “real” large-scale railway scene. The results were that the participants realized that the real, fuzzy trains were smaller than the models.
Dr Daniel Baker, from the University of York’s Department of Psychology, said: “In order for us to determine the true size of the objects we see around us, our visual system needs to estimate the distance to the object.
To get to an understanding of absolute scale, it can take into account the blurred parts of the image — such as out-of-focus areas produced by a camera — which involves a bit of complicated math to give the brain a knowledge of spatial scale.
However, this new study shows that we can be misled by our estimates of object size. Photographers are taking advantage of this by using a technique called ’tilt-shift miniaturization’, which can make life-size objects look like miniature models.
The results show that the human visual system is very flexible – it is sometimes able to accurately perceive size by exploiting what is known as ‘defocusing blur’, but at other times it is subject to other influences and fails to understand the size of an object in the real world. .
Professor Tim Mess, from Aston University, said: “Our results suggest that human vision can exploit focal blur to infer perceptual scale, but it does so roughly.
“Overall, our findings provide new insights into the computational mechanisms the human brain uses in perceptual judgments about the relationship between ourselves and the outside world.”