Gurney Journey

 Which is more important for face recognition: outline or tonal shapes?

Light enters our retinas, and the optic nerve feeds information back to the visual cortex. After that, the signal follows neural pathways to various areas scattered throughout the brain.

In addition to the visual streams, other streams of sensory information arrive via sound and touch. Those signal pathways also appear distributed around the brain. 

For a long time, neuroscientists supposed that all the various streams of sensory impulses must converge or fuse together at a central location, but it doesn't happen that way. 

Given the scattered nature of that neuronal activity, how is it that we feel that our perception is a single experience? 

According to neuroscientist Jeff Hawley's new conceptual model of the brain, the various areas in the cortex arrive at a preliminary conclusion of what they're looking at. They appear to form a consensus in a manner very much like voting. To do that they don't need to be in the same place.

Read More:

Sensor Fusion on Wikipedia

A Thousand Brains: A New Theory of Intelligence by Jeff Hawkins

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Neurobiologist Susan R. Barry was an adult when she acquired depth perception for the first time.

"Barry had been cross-eyed and stereoblind since early infancy. After half a century of perceiving her surroundings as flat and compressed, on that day she saw the city of Manhattan in stereo depth for first time in her life. As a neuroscientist, she understood just how extraordinary this transformation was, not only for herself but for the scientific understanding of the human brain. Scientists have long believed that the brain is malleable only during a "critical period" in early childhood. According to this theory, Barry's brain had organized itself when she was a baby to avoid double vision - and there was no way to rewire it as an adult. But Barry found an optometrist who prescribed a little-known program of vision therapy; after intensive training, Barry was ultimately able to accomplish what other scientists and even she herself had once considered impossible."

The story shows not only that the brain is malleable, but also that a conscious awareness of experience isn't the same as actually having that experience. As author Bruce Goldstein puts it, "Scientific knowledge is not enough." 

There's a lot of information online about the difference between the two hemispheres of the brain and what that means for artists.

Many commentators suggest that each of us is either a "left hemisphere person" or a "right hemisphere person," as if we think and act primarily with one dominant hemisphere. This idea originated from studies in the 1960s and '70s with patients whose two hemispheres had to be separated by cutting through the connecting nerve bundle called the corpus callosum.

The notion that has percolated through popular culture is that each half of the brain functions separately.

Recent studies reveal that the truth is actually more nuanced than that.

Iain McGilchrist, a psychologist who has investigated this topic, suggests that different hemispheres of the brain are actually engaged in similar cognitive tasks, but each half approaches that task in a different way.

The right half focuses more on the big picture, and the left hemisphere focuses more on the details. The right brain appreciates metaphor, poetry, humor, and music, while the left brain is more focused on the notes, the denotive facts, and the logical conclusions. 

Although they have somewhat different styles of information processing, the two hemispheres are both engaged as you navigate through most tasks, and they work together when you're creating a painting. 

In this YouTube video, which is illustrated by a whiteboard animation, Iain McGilchrist explains the lateralized brain, and how that affects our personal and cultural styles of thought. 

 

Iain McGilchrist's book is called The Master and His Emissary: The Divided Brain and the Making of the Western World 

Visual form agnosia is the inability to recognize familiar objects. The problem isn't just being able to name something that you see; it's understanding the meaning of them, recognizing what they are.

Roses from my video Flower Painting in the Wild

A person with such a condition might look at a bunch of roses and say it's "a cluster of convoluted pink forms held up by vertical green attachments."

People with visual form agnosia typically have otherwise normal eyesight, intelligence, memory, attention, and language ability. 

Scientists have studied patients with this condition, often caused by a brain injury. These studies have yielded insight about the localization of functions in the brain and the pathways followed by neural activity as images are decoded. Recognition of objects seems to happen in the sides of the brain, not along the top of the brain.

That led me to wonder if there's a resemblance between visual form agnosia and the particular mode an artist shifts into while doing a painting. That is, don't we have to shut off the "naming engine" or the "categorization machine" in order to really see what we're painting? 

Perhaps one day scientists will study what happens in an artist's brain at various stages of the process of drawing and painting. 

Vision doesn't occur passively. It's active, constructive, and largely unconscious.

And it doesn't happen all at once. Sometimes it takes a half second to process an image, and sometimes it takes a second or two. 

The light entering our eyes is translated and organized in stages, beginning with simple visual elements and proceeding to higher levels of interpretation. These stages of image processing start in the retina and continue in different parts of the brain.

Identifying the figure as a mythological flying horse and the whole pattern as a piece of art by M.C. Escher is the final and most sophisticated stage in image processing, involving several areas of the brain.

Eric R. Kandel et al., authors of a textbook on the Principles of Neural Science, describe the process this way:

"The brain analyzes a visual scene at three levels: low, intermediate, and high. At the lowest level, visual attributes such as local contrast, orientation, color, and movement are discriminated. The intermediate level involves analysis of the layout of scenes and of surface properties, parsing the visual image into surfaces and global contours, and distinguishing foreground from background. The highest level involves object recognition. Once a scene has been parsed by the brain and objects recognized, the objects can be matched with memories of shapes and their associated meanings."

Book: Principles of Neural Science by E.R. Kandel, et al.

Research Gate

In this 10 minute podcast, cognitive psychologist Dr. James Dunn talks about "super recognizers." These individuals have an extraordinary ability to recognize individuals, even in cases where the encounter was very brief and many years earlier. 

Super recognizers are also adept at correctly identifying someone whose face may be partially disguised by a face mask or a hat or a new hairstyle. The ability is the opposite of prosopagnosia, the neurological condition better known as face blindness.

Dog vision is different from human vision in several ways. They can't distinguish red and green.

And they don't have sharp focus in a central area of the retina. Instead of concentrating photoreceptors in the fovea centralis, which gives us humans very detailed and color-sensitive vision in the pinpoint center of our attention, they have a broader area of focus.

Dog vision may not be as sharp or as colorful as ours, but it's better at tracking fast-moving objects, because their eyes are optimized to respond quickly. 

From the book: Inside of a Dog: What Dogs See, Smell, and Know by Alexandra Horowitz