Nav: Home

Illusion reveals that the brain fills in peripheral vision

December 08, 2016

What we see in the periphery, just outside the direct focus of the eye, may sometimes be a visual illusion, according to new findings published in Psychological Science, a journal of the Association for Psychological Science. The findings suggest that even though our peripheral vision is less accurate and detailed than what we see in the center of the visual field, we may not notice a qualitative difference because our visual processing system actually fills in some of what we "see" in the periphery.

"Our findings show that, under the right circumstances, a large part of the periphery may become a visual illusion," says psychology researcher Marte Otten from the University of Amsterdam, lead author on the new research. "This effect seems to hold for many basic visual features, indicating that this 'filling in' is a general, and fundamental, perceptual mechanism."

As we go about daily life, we generally operate under the assumption that our perception of the world directly and accurately represents the outside world. But visual illusions of various kinds show us that this isn't always the case. As the brain processes incoming information about an external stimulus, we come to learn, it creates a representation of the outside world that can diverge from reality in noticeable ways.

Otten and colleagues wondered whether this same process might explain why we usually feel as though our peripheral vision is detailed and robust when it isn't.

"Perhaps our brain fills in what we see when the physical stimulus is not rich enough," she explains. "The brain represents peripheral vision with less detail, and these representations degrade faster than central vision. Therefore, we expected that peripheral vision should be very susceptible to illusory visual experiences, for many stimuli and large parts of the visual field."

Over a series of experiments, the researchers presented a total of 20 participants with a series of images. The participants focused on the center of the screen -- a central image appeared and then a different peripheral image gradually faded in. Participants were supposed to click the mouse as soon as the difference between the central patch and the periphery disappeared and the entire screen appeared to be uniform.

Otten and colleagues changed the defining characteristic of the central image in different experiments, varying its shape, orientation, luminance, shade, or motion.

The results showed that all of these characteristics were vulnerable to a uniformity illusion -- that is, participants incorrectly reported seeing a uniform image when the center and periphery were actually different.

The illusion was less likely to occur when the difference between the center and periphery was large; when the illusion did occur on these trials, it took longer to emerge.

Participants indicated that they felt roughly equally sure about their experience of uniformity when it actually did exist as when it was illusory. This suggests that the illusory experiences are similar to a visual experience based on a physical visual stimulus.

"The fun thing about this illusion is that you can to test this out for yourself," Otten says. "If you look up the illusion on http://www.uniformillusion.com you can find out just how real the illusory experience feels for you."

"The most surprising is that we found a new class of visual illusions with such a wide breadth, affecting many different types of stimuli and large parts of the visual field," Otten adds. "We hope to use this illusion as a tool to uncover why peripheral vision seems so rich and detailed, and more generally, to understand how the brain creates our visual perceptual experiences."
-end-
Co-authors on the research include Yair Pinto (University of Amsterdam, University of Sussex), Chris L.E. Paffen (Utrecht University), Anil K. Seth (University of Sussex), and Ryota Kanai (University of Sussex).

This research was supported by Intra-European Fellowships Marie Curie Grants No. 300184 to Y. Pinto and No. 329134 to M. Otten.

For more information about this study, please contact: Marte Otten at marte.otten@gmail.com.

The article abstract is available online: http://pss.sagepub.com/content/early/2016/11/12/0956797616672270.abstract

The APS journal Psychological Science is the highest ranked empirical journal in psychology. For a copy of the article "The Uniformity Illusion: Central Stimuli Can Determine Peripheral Perception" and access to other Psychological Science research findings, please contact Anna Mikulak at 202-293-9300 or amikulak@psychologicalscience.org.

Association for Psychological Science

Related Research Articles:

More Research News and Research Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: Meditations on Loneliness
Original broadcast date: April 24, 2020. We're a social species now living in isolation. But loneliness was a problem well before this era of social distancing. This hour, TED speakers explore how we can live and make peace with loneliness. Guests on the show include author and illustrator Jonny Sun, psychologist Susan Pinker, architect Grace Kim, and writer Suleika Jaouad.
Now Playing: Science for the People

#565 The Great Wide Indoors
We're all spending a bit more time indoors this summer than we probably figured. But did you ever stop to think about why the places we live and work as designed the way they are? And how they could be designed better? We're talking with Emily Anthes about her new book "The Great Indoors: The Surprising Science of how Buildings Shape our Behavior, Health and Happiness".
Now Playing: Radiolab

The Third. A TED Talk.
Jad gives a TED talk about his life as a journalist and how Radiolab has evolved over the years. Here's how TED described it:How do you end a story? Host of Radiolab Jad Abumrad tells how his search for an answer led him home to the mountains of Tennessee, where he met an unexpected teacher: Dolly Parton.Jad Nicholas Abumrad is a Lebanese-American radio host, composer and producer. He is the founder of the syndicated public radio program Radiolab, which is broadcast on over 600 radio stations nationwide and is downloaded more than 120 million times a year as a podcast. He also created More Perfect, a podcast that tells the stories behind the Supreme Court's most famous decisions. And most recently, Dolly Parton's America, a nine-episode podcast exploring the life and times of the iconic country music star. Abumrad has received three Peabody Awards and was named a MacArthur Fellow in 2011.