Vision, perception and the biology behind optical illusions What is perception and how does our visual hardware shape our perception of reality?
Here is an interesting article on the most current theory of the biology behind some optical illusions.
Consider the Kanizsa triangle. What causes the brain to draw lines in a picture?
http://neurosciencenews.com/visual-system-optical-illusions-3941/Neuronal feedback could change what we ‘see’.Ever see something that isn’t really there? Could your mind be playing tricks on you? The “tricks” might be your brain reacting to feedback between neurons in different parts of the visual system, according to a study published in the Journal of Neuroscience by Carnegie Mellon University Assistant Professor of Biological Sciences Sandra J. Kuhlman and colleagues.
Understanding this feedback system could provide new insight into the visual system’s neuronal circuitry and could have further implications for understanding how the brain interprets and understands sensory stimuli.
Many optical illusions make you see something that’s not there. Take the Kanizsa triangle: when you place three Pac-Man-like wedges in the right spot, you see a triangle, even though the edges of the triangle aren’t drawn.
“We see with both our brain and our eyes. Your brain is making inferences that allow you to see the triangle. It’s connecting the dots between the corners of the wedges,” said Kuhlman, who is a member of Carnegie Mellon’s BrainHub neuroscience initiative and the joint Carnegie Mellon/University of Pittsburgh Center for the Neural Basis of Cognition (CNBC). “Optical illusions illustrate some of the amazing things our visual system can do.”
When we look at an object, information about what we see travels through circuits of neurons beginning in the retina, through the thalamus and into the brain’s visual cortex. In the visual cortex, the information gets processed in multiple stages and is ultimately sent to the prefrontal cortex — the area of the brain that makes decisions, including how to respond to a given stimulus.
However, not all information stays on this forward moving path. At the secondary stage of processing in the visual cortex some neurons reverse course and send information back to the first stage of processing. Researchers at Carnegie Mellon wondered if this feedback could change how the neurons in the visual cortex respond to a stimulus and alter the messages being sent to the prefrontal cortex.
While there has been a good deal of research studying how information moves forward through the visual system, less has been done to study the impact of the information that moves backward. To find out if the information traveling from the secondary stage of processing back to the first stage impacted how information is encoded in the visual system, the researchers needed to quantify the magnitude of information that was being sent from the second stage back to the first stage. Using a mouse model, they recorded normal neuronal firing in the first stage of the visual cortex as the mouse looked at moving patterns that represented edges. They then silenced the neurons in the second stage using modified optogenetic technology. This halted the feedback of information from the second stage back to the first stage, and allowed the researchers to determine how much of the neuronal activity in the first stage of visual processing was the result of feedback.
Twenty percent of the neuronal activity in the visual cortex was the result of feedback, a concept Kuhlman calls reciprocal connectivity. This indicates that some of the information coming from the visual cortex is not a direct response to a visual stimuli, but is a response to how the stimuli was perceived by higher cortical areas.
The feedback, she says, might be what causes our brain to complete the undrawn lines in the Kanizsa triangle. But more importantly, it signifies that studying neuronal feedback is important to our understanding of how the brain works to process stimuli.
“This represents a new way to study visual perception and neural computation. If we want to truly understand the visual pathway, and cortical function in general, we have to understand these reciprocal connection,” Kuhlman said.
Ultimately, this neural feedback that involves parts of the brain interacting with one another to process a visual image, in a manner not directly related to the primary "forward" processing of a "seeing" an object, could be the part of the brain that "says" "I expect a triangle here, thus I will add non-existent lines to complete this expected triangle".
Full paper:
http://www.jneurosci.org/content/36/10/2904Secondly, do all humans view this optical illusion the same way? If not, what does that tell us about the underlying system that makes the optical illusion appear for most people?
http://www.richardgregory.org/papers/articles/seeing-after-blindness.pdfIn 1959 a gentleman by the name of Sidney Bradford, who had been blind since birth due to an infection, underwent a procedure to receive corneal grafts to restore his sight at age 52.
Richard Gregory and his research assistant Jean Wallace examined Mr Bradford's responses to optical illusions.
Bradford’s responses to well-known illusion figures were far from normal. He perceived far less distortion,and he did not experience the flipping ambiguity of the Necker Cube, or other such dynamic changes of appearance. Pictures looked flat and meaningless. Perspective meant nothing to his visual system,yet he could judge the distances and sizes of objects that were already familiar from touch, such as chairs scattered around the ward — although he was wildly wrong about distances to the ground from the hospital windows. Evidently, earlier touch experience and behaviour such as walking, calibrated and gave sense to his vision, which was almost useless for untouchable objects or pictures.
His unusual responses to the figures suggested that many illusions result from cognitive processing, rather than physiological signal processing occurring early in the visual system; this led to experiments and interesting controversies that persist today
A Neker cube:
As an aside, the real interesting take away from the Sidney Bradford case was that the man, blind since birth and newly sighted, could tell time by looking at the hands of the clock, as well as read (correctly) some words based on the shape of the upper case letters. At a children's school for the blind Mr. Bradford was taught to tell time and read by memorizing the shape of the hands and letters, respectively. Mr. Bradford was immediately able to transfer his identification of objects by touch to his new sight, indicating that there is a "cross-modal" transfer of touch to vision.
Further interesting scientific papers on perception, illusions and vision are here in Richard Gregory's publications:
http://www.richardgregory.org/papers/So one of the hypotheses that the Sidney Bradford case suggests, is that there is some common learning experience in humans who are sighted since birth that allows them to perceive the optical illusion.
For an
Eclipse Phase campaign the utility of exploring the space between perception and reality for writing adventures is self evident, particularly in a setting with Basilisk hacks.
Here are some rough ideas:
Perhaps the mechanism that makes transhumans susceptible to Basilisk hacks is embedded in their ego. Somewhere between visual perception and learning. To capitalize on a market for traumatized egos who want to protect them selves from another fall, Cognite could offer an experimental series of psychosurgeries to make egos more resistant (or totally immune to) some Basilisk hacks. Naturally this procedure would involve forking and successively merging "blind since birth" egos with the alpha ego. That procedure itself could have negative psychological impacts on the parent ego (likely the "blind since birth" egos require accelerated time like the Lost project with all it's associated baggage).
The political ramifications could be that reclaimers are highly supportive of this new technology because they hope to retake Earth with Basilisk hack immune shock troops. Naturally other transhumans political factions would find this dangerous to their agendas and seek to violently destroy all evidence of success in this experimental therapy.
Alternatively, in a more fictionalized sci-fi bent, perhaps the procedure for Basilisk immunity somehow makes the subject less than human. Or (spitballing fantasy here) some fraction of those egos subjected to the Basilisk immunity procedure can not only still perceive the optical illusions, but they simultaneously perceive the lack of illusions. Throw in the observer effect, and pineal gland stimulation for hand waving rational and you could justify that any horrible interaction between the treated egos and titan hack tech you want.
The concept of "truly perceiving reality invites supernatural attention and intrusion into our reality" is a common one. Arthur Machen's
The Great God Pan and HP Lovecraft's
From Beyond are great examples.
Let's marry this theme to the idea that messing with the brain's ability to perceive optical illusions can create a person with an "observer effect" special ability.
Say a character has this "observer effect" special ability. Add that the "observer effect" in this individual creates a Bad Thing to happen when the character observed something with one other person present. The Bad Thing could be that the observer character generates a basilisk hack
ex nihilo, which then immediately attacks/infects his non-observer compatriot; or in a more supernatural campaign the observer character unconsciously summons a fragment of Azathoth/Daoloth/whatever that bloodily eats his compatriot while the observer character gets away unharmed (but traumatized).
This type of plot could be used to spice up a standard "Haunted House" (or spaceship or research base). Terrible things happen in this Haunted House. The players plus the observer character (or maybe a player IS the observer character) are sent to investigate and they find out the house really isn't haunted/cursed, instead it is their companion that is the unwitting innocent supernatural Typhoid Mary.
In retrospect this idea is very similar thematically to the X-files episode
Soft Light where a character is essentially cursed with inadvertently killing people around him when he is alone with them. Oh well, nothing new under the sun right?
https://en.wikipedia.org/wiki/Soft_Light_(The_X-Files)There have got to be better plots that are closer to the science and I'd love to hear you guys make them.
