eyes

Violets, transform’d to eyes

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Researchers have known for decades that the eye does much more than just detect light. The dense patch of neurons in the retina also processes basic features of a scene before sending the information to the brain. For example, in 1964, scientists showed that some neurons in the retina fire up only in response to motion. What’s more, these “space-time” detectors have so-called direction selectivity, each one sensitive to objects moving in different directions. But exactly how that processing happens in the retina has remained a mystery. […]

Although researchers have imaged the retina microscopically in ultrathin sections, no computer algorithm has been able to accurately trace out the borders of all the neurons to map the circuitry. […]

Enter the EyeWire project, an online game that recruits volunteers to map out those cellular contours within a mouse’s retina.

{ Science | Continue reading }

‘The fire of hell is called eternal, only because it never ends.’ –Thomas Aquinas

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When you really focus your attention on something, you’re said to be “in the present moment.” But a new piece of research suggests that the “present moment” is actually […] a sort of composite—a product mostly of what we’re seeing now, but also influenced by what we’ve been seeing for the previous 15 seconds or so. They call this ephemeral boundary the “continuity field.”

{ Quartz | Continue reading }

photo { Richard Sandler }

The sadness will last forever

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There are many theories about why humans cry ranging from the biophysical to the evolutionary. One of the most compelling hypotheses is Jeffrey Kottler’s, discussed at length in his 1996 book The Language of Tears. Kottler believes that humans cry because, unlike every other animal, we take years and years to be able to fend for ourselves. Until that time, we need a behavior that can elicit the sympathetic consideration of our needs from those around us who are more capable (read: adults). We can’t just yell for help though—that would alert predators to helpless prey—so instead, we’ve developed a silent scream: we tear up. […]

In a study published in 2000, Vingerhoets and a team of researchers found that adults, unlike children, rarely cry in public. They wait until they’re in the privacy of their homes—when they are alone or, at most, in the company of one other adult. On the face of it, the “crying-as-communication” hypothesis does not fully hold up, and it certainly doesn’t explain why we cry when we’re alone, or in an airplane surrounded by strangers we have no connection to. […]

In the same 2000 study, Vingerhoet’s team also discovered that, in adults, crying is most likely to follow a few specific antecedents. When asked to choose from a wide range of reasons for recent spells of crying, participants in the study chose “separation” or “rejection” far more often than other options, which included things like “pain and injury” and “criticism.” Also of note is that, of those who answered “rejection,” the most common subcategory selected was “loneliness.”

{ The Atlantic | Continue reading }

photo { Adrienne Grunwald }

What if another universe

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When a healthy person watches a smoothly moving object (say, an airplane crossing the sky), she tracks the plane with a smooth, continuous eye movement to match its displacement. This action is called smooth pursuit. But smooth pursuit isn’t smooth for most patients with schizophrenia. Their eyes often fall behind and they make a series of quick, tiny jerks to catch up or even dart ahead of their target. For the better part of a century, this movement pattern would remain a mystery. But in recent decades, scientific discoveries have lead to a better understanding of smooth pursuit eye movements.

{ Garden of the Mind | Continue reading }

‘The History of the world is none other than the progress of the consciousness of Freedom.’ –Hegel

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At this very moment, your eyes and brain are performing an astounding series of coordinated operations.

Light rays from the screen are hitting your retina, the sheet of light-sensitive cells that lines the back wall of each of your eyes. Those cells, in turn, are converting light into electrical pulses that can be decoded by your brain.

The electrical messages travel down the optic nerve to your thalamus, a relay center for sensory information in the middle of the brain, and from the thalamus to the visual cortex at the back of your head. In the visual cortex, the message jumps from one layer of tissue to the next, allowing you to determine the shape and color and movement of the thing in your visual field. From there the neural signal heads to other brain areas, such as the frontal cortex, for yet more complex levels of association and interpretation. All of this means that in a matter of milliseconds, you know whether this particular combination of light rays is a moving object, say, or a familiar face, or a readable word. […]

This post is about a question that’s long been debated among scientists and philosophers: At what point in that chain of operations does the visual system begin to integrate information from other systems, like touches, tastes, smells, and sounds? What about even more complex inputs, like memories, categories, and words?

We know the integration happens at some point. If you see a lion running toward you, you will respond to that sight differently depending on if you are roaming alone in the Serengeti or visiting the zoo. Even if the two sights are exactly the same, and presenting the same optical input to your retinas, your brain will use your memories and knowledge to put your vision into context

{ Virginia Hughes/National Geographic | Continue reading }

photo { Harry Callahan }

He assumes that if the infinite series of divisions he describes were repeated infinitely many times then a definite collection of parts would result

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In the middle of the 20th century, experimental psychologists began to notice a strange interaction between human vision and time. If they showed people flashes of light close together in time, subjects experienced the flashes as if they all occurred simultaneously. When they asked people to detect faint images, the speed of their subjects’ responses waxed and waned according to a mysterious but predictable rhythm. Taken together, the results pointed to one conclusion: that human vision operates within a particular time window – about 100 milliseconds, or one-tenth of a second.

[…] Pretty much anyone with a pair of eyes will tell you that vision feels smooth and unbroken. But is it truly as continuous as it feels, or might it occur in discrete chunks of time?

{ Garden of the Mind | Continue reading }

screenshot { Ivan Mozzhukhin, Le brasier ardent, 1923 }

‘But Vegas is really my first home.’ –David Copperfield

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{ The Shepard tables use perspective and other contextual clues (such as the legs) to fool our visual system into thinking that two tabletops are different shapes, although measurement will confirm that they are in fact identical. | Natural selection has not equipped us with a truthful visual system }

And say what thou seest yond

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Adults make eye contact between 30% and 60% of the time in an average conversation, says the communications-analytics company Quantified Impressions. But the Austin, Texas, company says people should be making eye contact 60% to 70% of the time to create a sense of emotional connection, according to its analysis of 3,000 people speaking to individuals and groups.

One barrier to contact is the use of mobile devices for multitasking. Among twentysomethings, “it’s almost become culturally acceptable to answer that phone at dinner, or to glance down at the baseball scores.” […] Young adults who are dissatisfied with their lives or relationships feel compelled to check mobile gadgets repeatedly to see what social opportunities they are missing—even when they don’t enjoy it, the study says. […]

Eye contact can be a tool for influencing others. Looking at a colleague when speaking conveys confidence and respect. Prolonged eye contact during a debate or disagreement can signal you’re standing your ground. It also points to your place on the food chain: People who are high-status tend to look longer at people they’re talking to, compared with others, says a 2009 research review in Image and Vision Computing.

{ WSJ | Continue reading }

How can science be susceptible of infinite progress if its object does not have an inner infinity?

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Normal vision is essentially a spatial sense that often relies upon touch and movement during and after development, there is often a correlation between how an object looks and how it feels.

Moreover, as a child’s senses develop, there is cross-referencing between the various senses. Indeed, where the links between the senses are not made, there may be developmental problems or delays.

This should be taken into consideration when training new users of visual prosthetics, artificial retinas, or bionic eyes, suggest researchers in Australia.

{ EurekAlert | Continue reading }

photo { Elena Amagro }

The crabs at Sam Wo’s… Tracy’s face…

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Proponents of Neuro-Linguistic Programming (NLP) claim that certain eye-movements are reliable indicators of lying. According to this notion, a person looking up to their right suggests a lie whereas looking up to their left is indicative of truth telling. Despite widespread belief in this claim, no previous research has examined its validity. […]

Three studies provided no evidence to support the notion that the patterns of eye-movements promoted by many NLP practitioners aid lie detection. This is in line with findings from a considerable amount of previous work showing that facial clues (including eye movements) are poor indicators of deception.

{ PLoS | Continue reading }

In the two ‘four-eyed’ dogs, messengers of Yama

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“GB” is a 28 year old man with a curious condition: his optic nerves are in the wrong place.

Most people have an optic chiasm, a crossroads where half of the signals from each eye cross over the midline, in such a way that each half of the brain gets information from one side of space. GB, however, was born with achiasma – the absence of this crossover. It’s an extremely rare disorder in humans, although it’s more common in some breeds of animals, such as Belgian sheepdogs. […]

In the absence of a left-right crossover, all of the signals from GB’s left eye end up in his left visual cortex, and vice versa. But the question was, how does the brain make sense of it? Normally, remember, each half of the cortex corresponds to half our visual field. But in GB’s brain, each half has to cope with the whole visual field – twice as much space (even though it’s getting no more signals than normal.)

{ Neuroskeptic | Continue reading }

In blue dungarees, stands up in the gallery, holding in each hand an orange citron

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The researchers also found that men require a slightly longer wavelength to see the same hue as women; an object that women experience as orange will look slightly more yellowish to men, while green will look more blue-green to men.

This last part doesn’t confer an advantage on either sex, but it does demonstrate, Abramov says, that “the nervous system that deals with color cannot be wired in the exact same way in males as in females.” He believes the answer lies in testosterone and other androgens.

{ Smithsonian | Continue reading }

photo { Nicholas Nixon }