Where visual search happens in the brain

UC SANTA BARBARA (US) — When we look for something, we rely on environmental cues and scene context. New research shows where in the brain this process occurs.

Our brains developed this pattern of search over the millennia of human evolution, It’s an ability that has not only helped us find food and avoid danger in humankind’s earliest days, but also continues to aid us today, in tasks like driving to work, going shopping, and reading X-rays.

Though a seemingly simple and intuitive strategy, that visual search function—a process that takes mere seconds for the human brain—is still something that a computer, despite technological advances, can’t do as accurately.

The researchers flashed these photos of scenes before the subjects. Highlighted spots indicate where the subjects indicated the most likely area to contain the object named in each scene. Superimposed is a back view of one hemisphere of the brain; the red area is the location of the Lateral Occipital Complex. (Credit: UC Santa Barbara)

“Behind what seems to be automatic is a lot of sophisticated machinery in our brain,” says Miguel Eckstein, professor in University of California, Santa Barbara’s department of psychological & brain sciences. “A great part of our brain is dedicated to vision.”

Where this—the search for objects using scene and other objects—occurs in the brain is little understood, and is for the first time discussed in a paper published recently in the Journal of Neuroscience.

‘Made you look’

The researchers flashed hundreds images of indoor and outdoor scenes before observers, and instructed them to search for certain objects that were consistent with those scenes. Half of the images, however, did not contain the target object. During the trials, the subjects were asked to indicate whether the target object was present in the scene.

The researchers were particularly interested in the images that did not contain the target. Another measure was taken to determine where subjects expected specific objects to be in target-absent scenes.

Invariably, the subjects would indicate similar areas: If presented with a living room scene and told to look for a clock or a painting, they would indicate the wall; if shown a photo of a bathroom and told to indicate where to expect a hand soap or toothbrush, they would indicate the sink.

The searched object’s contextual location in the scenes, according to the study, is represented in the area called the lateral occipital complex (LOC), a place that corresponds roughly to the lower back portion of the head, toward the side. This area, according to Eckstein, has the ability to account for other objects in the scene that often appear in close spatial proximity with the searched object—something computers are only recently being taught to do.

Wrong targets

“So, if you’re looking for a computer mouse on a cluttered desk, a machine would be looking for things shaped like a mouse. It might find it, but it might see other objects of similar shape, and classify that as a mouse,” Eckstein says. Computer vision systems might also not associate their target with specific locations or other objects. So, to a machine, the floor is just as likely a place for a mouse as a desk.

The LOC, on the other hand, would contain the information the brain needs to direct a person’s attention and gaze first toward the most likely place that a mouse might be, such as on top of the desk, or near the keyboard. From there, other visual parts of the brain go to work, searching for particular characteristics, or determining the target’s presence.

So strong is the scene context in biasing search, says Eckstein, that if another similar-looking object was placed in the location where the mouse is likely to be, and that scene briefly flashed before your eyes, you would likely—erroneously—interpret that object as the mouse.

Expert searchers

While scene context information has been found highly active in the LOC, other visual areas of the brain are also influenced by context to certain degrees, including the interparietal sulcus, located near the top of the head; and the retrosplenial cortex, found in the brain’s interior.

“Since contextual guidance is a critical strategy that allows humans to rapidly find objects in scenes, studying the brain areas involved in normal humans might help us to gain a better understanding of neural areas involved in those with visual search deficits, such as brain-damaged patients and the elderly,” Eckstein says.

“Also, a large component of becoming an expert searcher—like radiologists or fishermen—is exploiting contextual relationships to search. Thus, understanding the neural basis of contextual guidance might allow us to gain a better understanding about what brain areas are critical to gain search expertise.”

Additional researchers from the Institute for Collaborative Biotechnologies at UC Santa Barbara contributed to the study, which was supported by the National Eye Institute.

Source: UC Santa Barbara

chat4 Comments


  1. Rose McClean

    Interesting read! It’s amazing what the human brain is capable of; many processes which have yet to be discovered by endocrinologists and other brain experts. This sounds like a topic that deserves better exploration and research especially of other benefits of the LOC.

  2. Bob Washick, Ed.D. LD

    My degree is in Learning Disabilities. My mission – why do some people read and write, and others have difficulty. Over the years I was in direct contact with mentally challenged, slow learner, regular student, gifted, gifted creative, blind, deaf … in short the gamut on the continuum of education. What did they have in common, what did they lack. The basics I realized was the ability to read and the ability to write. We probably take each for granted, but I wanted to know why some people SAW a letter or word backwards, different, in reverse, substitution etc. So, I started with the capital printed alphabet. Let’s make an +, actually a horizontal line, and cross it with a vertical line. In the right hand lower corner print an O, in the left hand lower corner, print an O left handed backwards, in the top upper right hand side, print an O upside down, in the left hand side make an O left handed upside down backwards. the results are basically the same, there is less error, and in the printed alphabet because so many letters can be printed left handed, right handed upside down, reversed etc – we are more assured of success. So with handedness or laterality at this level there is relatively little difficulty.

    But I noticed that students had the greatest difficulty in third grade. They had the most difficulty because of Cursive writing. Because of the loop that ties it together, you may follow the same procedure as above but get an O, but you know it is a little different. Many teachers for instance cannot write a cursive Q, yet it looks like an O, which is what they usually make and then put a small diagonal line at the bottom, indicating a Q. The Q is the exact opposite of the O – and that is where the difficulty occurs – we have reversals. And if for example we learned to print a capital A, from the Bottom line, diagonally up, stop, diagonally opposite and down, and connect both with a horizontal line, we have a perfect A (although it should have been started at the top). Why? Because research indicates that when you learn something, you go back to that learning point. A capital cursive A, starts from the Top down, not the Bottom up (so we have confusion as where to start), and although a student may start from the bottom in cursive, they will go up, down and around, repeat it and when they get to the bottom swing out – looks good, but the letters that follow will be confused, and that is why third grade for the most part is the most difficult.

    So when we talk vision, it isn’t only what we see, but how we produce what we see. It is why I was fascinated with the cave paintings in Spain and France. Animals, hands with curves and color. Why the curve, and that was answered when I read about Drs. Wiesel and Hubel who elicited design patterns from the visual cortex of cats: and lines through the visual cortex changed into curves, plasticity. And A, could be a B, or a car, or an animal. I knew there had to be something way prior to the caves, and that was answered in 2002 when Dr. Henshilwood discovered design patterns in the Blombos Caves of Africa 70,000 years old, 35,000 years older than the cave drawings. Similar designs might be found on the Wide Range Achievement Test, or the Bender Gestalt, but what was more exciting is that I had similar designs copyrighted in 1978, You don’t design pyramids, temples, spears, arrow heads, building all things around us without linear movement. I believe the visual motor section of the brain has basically stayed the same, but it accommodated new environments and has improved man from even the days earlier than the Blombos caves to today’s computer. I do change reading and writing in nine hours of work by design patterns.

  3. Joanne

    Great information.
    I am looking for information regarding vision recovery therapy for my 22 y/o son who had a stroke secondary to lupus.Please help.

  4. Brianna

    interesting it will help me with my science fair

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