Philosophy of Mind came into its most compelling forms during the age of modern philosophy beginning with René Descartes. Perhaps infamously, Descartes claimed that mind and body are two distinct substances – philosophical jargon for what exists without the aid of any other thing. For Descartes, the world was clearly and distinctly physical in one sense and entirely mental in another. This seems perplexing, and Descartes did concede that the mind and body were closely intertwined and appeared to act with respect to one another, but his arguments clearly press that they are not causally connected in any way. These notions of dualism seem nearly preposterous with the advent of modern science, but were nonetheless important in developing our thought about the mind in the modern era.

Dualism gave rise to other interesting, yet now strongly refuted movements. One of these was idealism, or the doctrine argued famously by George Berkeley that states that all that exists are either ‘ideas’ or minds that perceive them. In this sense, an idea is defined as that which is perceived, inclusive of information imprinted on the senses, passions and operations of the mind, and conceptions formed by imagination and memory. Importantly, Berkeley argues that these ideas exist ‘in the mind’ exclusively: that is, they are purely mental and all things are simply combinations and aggregations of ideas. These immaterial ‘ideas’ then, are the only objects of human knowledge under idealism, and this theory denies the existence of physical objects entirely! The notion seems preposterous, but there is a very interesting argument found within idealism that can throw our conception of perception for quite the proverbial loop.

One of the main arguments against idealism is the apparent true existence of material objects in the external world. Modern science has allowed us to know with a degree of certainty that we exist in a world that contains physical entities separate from our mental space. Bertrand Russsel, a physicalist, famously made such arguments for the existence of the material world. He coined the term ‘sense data’ to refer to that which we perceive from objects in the environment, e.g. the light rays reflecting off of them. In his thinking, this sense data is caused by an actual material object in the external world, thus endorsing the existence of physical objects. This certainly seems more plausible than idealism given our current level of understanding about the physical world. However, the idealist refute of physicalism draws on an idea called perceptual relativity that is interesting in itself and worth knowing about.

A simple philosophical approach to perception.

Perceptual relativity works similarly to the theory of relativity from physics, but applies it to perceptual content, and it is with this crafty syllogism that an idealist can argue that nothing really exists outside our own minds and ideas. If the idealist accepts that the objects perceived are ideas that exist only within the mind of the perceiver and those things are made up of more ideas which also only exist in the mind of the perceiver, it follows that each perceiver apprehends a different object entirely, rather than a different affection of the same object as a consequence of having different points of view. In other words, each person looking at a common object perceives an entirely unique object, just as if they were looking at two completely different things, e.g. a house and a boat. This seems absurd, but it is nonetheless effective for arguing the physical world out of existence. Taking ideas as exclusively mental phenomena, it remains logically valid to argue that each person perceives a different idea when looking at the same object in that different angles or in different levels of light and shadow make the object of each person’s perception unique to them alone.

Your may see squares A and B as different shades of grey. Look again - they are identical.

While the argument from perceptual relativity is interesting, it remains completely absurd in our modern context. Given that we can forcefully argue for the existence of the material world down to the level of molecules, atoms and subatomic particles that (perhaps) move faster than the speed of light, the idealist well seems to have run dry. It seems evident, if not universally true, that there is an external world filled with a variety of physical objects that exist in a space outside our minds. We may have thoughts of said objects and file them into our minds, but it by no means follows from this that an object solely exists in our minds and is not like the ideas of others about the same object. However, the flip side of this comfortable position would make an assertion about material objects themselves. What are they really made of? On a deep level, they are simply electricity – energetically favorable collisions of packets of energy that are perceived by our sense organs and constructed into a nice, organized stream of consciousness by our brains. To get even loftier, we’ve developed quite a system to differentiate all the different types of electricity out there by giving them names like tree, book or cheeseburger. These are really just ideas about the various clouds of electricity we interact with every day, so how far from idealism have we really come? Are our ideas about voltage simply existing within our own minds as a function of the information our brain is wiling to let us perceive?

What do you see?

References:

Treatise Concerning Human Knowledge – George Berkeley

The Problems Of Philosophy – Bertrand Russell

Most would agree that the most important of our basic senses is sight. Without it, many basic forms of communication fall apart, the vibrance of the world around us dulls, and our understanding and ability to sense the complexity of the physical world diminishes. Without the ability to see, it would logically be impossible to portray our surroundings artistically in a coherent and visually realistic manner…

…wait…what?

Esref was born without the privilege of sight. As a result, he never developed the thalamo-cortical projections from the lateral geniculate nucleus (LGN) to the primary visual cortex necessary for sight perception. However, instead of letting his occipital lobe go to waste, Esref’s brain adapted by using that same cortical real estate for other senses, primarily touch.

With Esref’s enhanced sense of touch he claims he can, “see more with his fingers than sighted people can see with their eyes.” A bold statement: after all, Esref has no idea what seeing is like. Conversely, sighted people don’t know what the sense of touch is like when the visual cortex becomes involved, so can we really deny his claim? The circular nature of this subjective discussion renders both opinions null but it does raise the question: is a subjective experience a product of the sensory modality involved or is it a product of the cortical area involved? And what exactly is Esref subjectively perceiving when he is feeling his way through a landscape? Is it as vivid as the subjective experience that sighted people perceive? It seems this question is impossible to resolve but seeing the landscapes Esref paints makes one believe that he is indeed sensing the world just as vividly as the rest of us.

Esref provides a new perspective on perception which throws a kink into anyone’s previously held beliefs about subjective experience and raises many internal questions. Personally, this new perspective leaves me with one question in particular: we can all agree that the 2003 blockbuster Daredevil was horrible, but wasn’t the rooftop rain scene where the blind Ben Affleck uses the sound of the raindrops on Jennifer Garner’s face to create a mental construct of her one of the most forward thinking, cognitive science-inspired scenes in all of cinematography?

Foreshortening, convergence and drawings from a blind adult – Perception

How you feel influences what you see, it is not just what you see that influences how you feel; a top down approach to understanding the visual system.

Affective Circumplex: Affect can vary in terms of valence (positive/negative) and arousal (high/low).

A great analogy for understanding how affect (the experience of an emotion) influences perception is to think of affect as a spotlight, or a source of “attention” that sheds light on the external world. This is known as a top-down process because the cortical and sub cortical levels of the brain directly influence what one externally experiences. This is opposed to a bottom-up process wherein external stimuli influences processing in the brain (an example of this process would be hearing something hit the floor behind you and immediately shifting your attention to that object). The brain uses both of these processes interchangeably, but it has only been recently that a top-down understanding of the visual system (a system that has classically been believed to be primarily regulated by external stimuli and how such stimuli influence attention) has been accepted. Many studies by Lisa Feldman Barrett and the Interdisciplinary Affective Sciences lab at Northeastern University seem to have proved strong evidence against the popular claim that the bottom-up system is the sole means by which perception can be influenced.

Affect has a greater influence on our perception than many would think. If placed in an unpleasant mood state, many people are usually more inclined to attend to smiling, scowling, and neutral faces. If placed in a pleasant mood state, however, people tend to be more inclined to attend to smiling faces. Indeed, during a binocular rivalry test in which a specific face (smiling, scowling or neutral) was presented to one of a test subject’s eyes, and a house to the other, mood induction was shown to determine which face would be viewed. The two percepts in this test compete for visual dominance, and it was apparent that the mood of the test subject directly influenced if the he/she would be more likely to attend to the faces and report whether they viewed a scowling, smiling, or neutral face. This test, and many others, seem to show that our affective state can directly influence what we deem as important to attend to in day to day life. Moreover, Could the gossip of other people, and what they tell us to believe as having “negative” or “positive” connotations truly influence our own sense of perception?

It is surprising to think that something as run of the mill as gossip could influence what we see. But, gossip is a social behavior that provides information (negative or positive) about another person, and thus it makes sense that such information could seep in and influence our perception. As Lisa Feldman Barret states in the video above, a neutral face that was gossiped about negatively was seen more often than a positive face that was gossiped about, a neutral face presented but not gossiped about or a novel face. While it is known that faces are usually more salient to us as a whole since we have evolved to be more attuned to faces, gossiped faces have been shown to be even more salient to us than faces alone. This study seems to show the kind of top down processing that can occur and influence our latent perception of certain things, as previously stored information derived from gossip influences what we tend to attend to, and how we perceive it!

Science: Visual Impact of Gossip – Sciencexpress

The Visual Impact of Gossip (supporting online material) – Science

See it with feeling: affective predictions during object perception – Philosophical Transactions of the Royal Society

What you feel influences what you see: The role of affective feelings in resolving binocular rivalry – Journal of Experimental Psychology

“Magic mirror on the wall, who is the fairest one of all” says the evil Queen of Snow White and the Seven Dwarfs. I don’t deny that growing up on Disney gave me a somewhat skewed sense of reality at times. Wouldn’t it be nice to all have our own magic mirrors, constantly reminding us how wonderful and beautiful we are in the midst of the stress that is life?

A recent study by researchers at Cornell University have shown that we may actually have such a magic mirror – Facebook, as fate would have it. There are varying opinions concerning internet use on our personalities, but this study shows that Facebook can have a short term positive effect on self esteem.

The authors set out to test two models of self perception. The first is Objective Self Awareness (OSA). According to this model, people analyze themselves according to how well they can adhere to social norms. This can not only be carried out through internal self reflection, but also “playbacks” of a self by using devices such as a mirror or audio recording. Facebook can be used as grounds to test the OSA because profiles contain information about the self like pictures. The second model is the Hyperpersonal Model. This is carried out through selective self-presentation. If this model is correct, Facebook is also a good platform to support it, as profiles allow users to selectively share information about themselves. Based on the model, they will share what they like about themselves, and thus would have higher self esteem after looking at only good qualities on their profile.

Participants in the study were in two general groups – the noninternet and internet group. The noninternet subjects sat in a room with computers, and mirrors in front of the computer screens. They were asked to fill out a questionnaire about how they were feeling. In contrast, the internet group participants were told to go on Facebook for three minutes. Afterwards, they filled out a questionnaire including questions such as “Did you only view your profile?” or “Did you edit your profile?”

Out of all the participants, the group with the highest reported self esteem were those participants that edited their profile while on Facebook. The next highest were those that had viewed their own profile, or a mix of their own profile as well as others. Those that were only allowed to look at themselves in a mirror reported having low self esteem. Thus, according to the OSA and Hyperpersonal Model, Facebook enhances the user’s self esteem by playing on attributes that the user finds positive.

While this study showed very short-term self esteem boosts, it does not incorporate many factors that should be necessary on a study of social networking websites. Did the subjects studied have an abnormally high number of friends? This could boost self esteem by making the user feel popular. Long term studies would be necessary to determine if contant profile refreshing would actually make the Facebook user doubt him/herself, or feel worse when self-defined “bad” attributes were expressed in real life? This study is a good start to the exploration of social networking sites on short term self esteem, but much more work needs to be done to determine long term benefits or limits.

Mirror, Mirror on my Facebook Wall: Effects of Exposure to Facebook on Self-Esteem – Cyberpsychology, Behavior, and Social Networking

In early 2007, a 64-year-old Swiss woman was admitted to the emergency room of a local hospital after having suffered a moderate right hemispheric stroke. Several days following her hospitalization, the woman began to experience what she described to her physicians as a “pale,” “transparent” arm that began at her elbow, which she could move and utilize to complete actions. The phenomenon the Swiss woman experienced was a Supernumerary Phantom Limb (SPL), which is characterized by the sensation of possessing an extra limb that did not exist previously. Though uncommon, conditions such as SPL and phantom limb (the sensation that a missing limb is still attached to the body) typically arise due to some form of insult to the somatosensory region of the brain or from the removal or lack of body parts.

The third arm illusion at the Karolinska Institute in Stockholm, Sweden.

In the healthy brain, multisensory circuits organize visual, tactile, and proprioceptive inputs to the brain in order to compose a somatotopic map of which body parts are inherently our own. However, even the normal brain can be manipulated into believing in the existence of an extra limb. One method of manipulation is the rubber hand illusion, a technique that investigates bodily self-perception by placing a rubber hand next to a real hand and then stimulating both the real and fake limbs. Researchers Arvid Guterstam, Valeria Petkova, and Henrik Ehrsson of the Karolinska Institute in Stockholm, Sweden modified the techniques of the rubber hand illusion to study the representation of the real and fake hands in the brain and investigate whether, in order to accommodate for the new somatotopic representation of the fake limb, the brain would decrease its representation of the real hand.

By stimulating both limbs in a temporally and spatially congruent manner, The Karolinska team found that subjects effectively perceived the artificial hand as an additional limb without any significant disownership of the actual hand. However, in order to effectively elicit this illusion, both the false and real hands had to receive equivalent sensory, proprioceptive, and visual inputs. Results of this study indicate not only that identical, properly timed sensory input and integration is essential for initiating an SPL response in the healthy brain, but also that the brain is able to modify its somatotopic map to simultaneously accept two possibilities for self-identification.

Since current neuroprosthetic techniques only consider the functional limitations of paralysis, there is no compensation for the sensory limitations suffered by paralyzed individuals. However, the findings of the Karolinska team’s study suggest that it may be possible to create an illusion of a holistic multisensory experience for a paralyzed individual by incorporating supernumerary prosthesis into treatment techniques.  Hopefully, these discoveries will help researchers and bioengineers rethink their understanding of body-representation in the neuroprosthetic world.

A Mind Trick May Help Advance Prosthetics – LiveScience

The Illusion of Owning a Third Arm: Research Article – PlosOne

Seeing the phantom: A functional magnetic resonance imaging study of a supernumerary phantom limb – Annals of Neurology

Synesthesia is a neurological condition which joins sensory perceptions. The most common variety links numbers and letters (and often words like the days of the week) with colors. However people with synethesia can experience a slew of unique sensations ranging from tasting shapes to seeing sounds.

In neurologist Richard Cytowic’s book, ‘The Man Who Tasted Shapes’, a synesthetic dinner host describes his experiences: “When I taste something with an intense flavor, the feeling sweeps down my arms into my fingertips. I feel its weight, texture, [temperature], everything. I feel it like I’m actually grasping something.” For him, the taste and aroma of a meal elicit a strong tactile sensation.

Before extensive studies had been conducted on this condition, accounts of synathetic experiences were viewed as out-of-the-ordinary imaginative metaphors and not taken seriously. But in recent years Cytowic has heavily researched synesthesia and has determined its diagnostic criteria, the most significant being that these mixed perceptions are involuntary and automatic.

Tests such as the one below have shown to prove the case.  When the image to the left is presented to an individual without the condition, he/she considers it slightly difficult to distinguish the 5’s from the 2’s. Synesthetes (in particular those with a number-color association) can almost seamlessly make the distinction between the numbers due to the specific colors which they may have come to innately pair with them (as the image on the right shows, the synesthete associates 5 with green and 2 with red).

There have been multiple theories for synesthesia. A popular one suggested that it was caused by neural “cross-wiring” between interpretive areas. For example, a color processing region in the brain’s visual cortex called V4 lies adjacent to an area responsible for identifying letters and numbers, and a mixed perception of color and letters/numbers could be attributed to cross activation between these areas.

However,  Cytowic and his collegue David Eagleman propose a better hypothesis: that the neurological condition is really caused by a slight difference in the balance of excitation and inhibition. When chemical inhibitors, which repress other types of processing during a specific sense experience, are blocked, it is possible to sense blue from a red object without any contradiction. This theory was put forward because we know that non-synesthetes can aquire synethesic “symptoms” under the influence of psychoactive drugs like LSD.  So, we’re all capable of producing unnatural sensory combinations, but a lucky few of us can do it everyday.

The Man Who Tasted Shapes by Richard E. Cytowic

Dr. Richard E. Cytowic’s Website

Neurocognitive Mechanisms of Synesthesia

A little self-education goes a long way. Let Richard Dawkins enlighten you (and if you’ve seen this already, it’s never a bad idea to brush up on the basics of life):

Finding Nemo's Marlin

In Disney/Pixar’s “Finding Nemo,” Marlin and Dory are swimming through murky waters en route to Sydney Harbor. Marlin suddenly exclaims, “Wait, I have definitely seen this floating speck before. That means we’ve passed it before and that means we’re going in circles and that means we’re not going straight!” – and he is probably right.

Is it really possible that when we cannot see where we are going, we actually travel in circles? Souman et al. tested this belief through a variety of experiments. They found in all cases that when deprived of a visual stimulus, it is actually impossible to travel in a straight line.

The first set of experiments had participants travel through a wood without visual impediments (such as blindfolds). One set of subjects traveled through the woods when it was cloudy, the second set when it was sunny. All of the cloudy group walked in circles and walked in areas that they had previously been, without noticing they had crossed a previous path. In contrast, all of the subjects who could see the sun were able to maintain a course that was relatively straight and had no circles.

The experiment was also performed on blindfolded subjects in an open field.

Paths of Blindfolded Subjects

The blue paths correspond to the subjects that walked on cloudy days. Their paths are mostly curved with many circles. The small straight areas of walking are most likely caused by the setup of the trial – participants walked for a period of time, then were unblindfolded and allowed to walk to the starting point of the next walking block. Even so, when blindfolded, lack of a visual stimulus when blindfolded always resulted in walking in curved motions or in circles. This contrasts the yellow path; this subject walked on a sunny day, and maintained a straight course for a long distance.

What causes this strange phenomenon? Could it perhaps be subtle differences in leg length that introduce a bias to walk in one direction, thus accounting for the circular motion? Nope – the circle directions were still random. Adding shoe soles to add a more than subtle difference in leg length didn’t make a difference: the participants continued to walk in random circles.

Perhaps the only explanation is that our vision is so necessary for our daily lives that our body randomizes without it. This idea is demonstrated in studies in which subjects are kept in a room with constant lighting: their biological clocks become completely randomized with no night and day inputs. More studies should be performed to truly understand the importance of the visual system. Since we rely so heavily on vision, is it natural for movements to become randomized without it? Do those who are blind from birth experience the same walking in circles phenomenon? For now, the conclusion here is that the sensory systems are complex and there is still much work to be done in understanding this strange phenomenon. So, if you ever find yourself lost in murky Australian waters, you probably should not just keep swimming, but rather, ask a friendly passing whale for directions.

A Mystery: Why Can’t We Walk Straight? : Krulwich Wonders… – NPR

Walking Straight into Circles – Current Biology

It was an average Wednesday night at 8, and I was channel surfing. As I changed the channels I heard singing; I knew instantly that the show was American Idol.  Most of you watch or have watched the show in the past and time and time again it befuddles me to think how these individuals think that they can sing. Most of the singers not only have piercing voices, but they are off key and sound terrible. After most auditions, the contestants – although I know it was horrible – still believe their rendition of a Whitney Houston song was outstanding. If you are like me then you want to know why.

Tone-deaf individuals do not have brain damage or trouble hearing, and they are definitely not suffering from a lack of exposure to music.  So what actually makes people unable to understand their inability to sing? Researchers conducted an experiment that tested the connectivity of the arcuate fasciculus (AF), which connects the temporoparietal junction (the place where the temporal and parietal lobes meet), with the frontal cortex in the brain. This junction allows neural substrates of sound perception and production to be connected. The researchers hypothesized that there are structural and functional abnormalities that contribute to tone deafness.

To test their hypothesis, structural MRIs with diffusion tensor imaging (DTI) were performed on the patients. DTI is a type of MRI that allows researchers to map internal structures with the diffusion of water. After processing the information, the maps identified that the right superior AF was diminished compared to control, signifying that the AF is disrupted in tone-deaf individuals. Also, resultant fibers in tone-deaf individuals projected dorsally toward the parietal lobe and/or translocally to the left hemisphere and not toward the ipsilateral inferior frontal gyrus where normal individuals have projections.The imaging and testing of the AF led researchers to conclude that the superior branch is responsible for fine-grained discrimination, and the inferior branch is responsible for automatic matching of sound output to its target. They also tested the volume of the fibers connecting each part of the brain and discovered that tone-deaf individuals have a lower volume of fibers than the control, which is important for conscious pitch determination and the degree of action-perception mismatch. According to the experiment, both the superior and inferior branches of the AF are needed for accurate perception and production.

Figure 1: A comparison between the regions of interest of the posterior superior temporal gyrus (pSTG) and the   posterior inferior frontal gyrus (pIFG) of the right side of the brain

Tone-deafness is a new disconnection syndrome that deals with impaired pitch perception and vocal sound projection. There are no known genes that are associated with this condition that affects the AF fibers and their connection between the superior and inferior areas of the brain. So for all of you non-tone-deaf American Idol viewers, you will just have to sit through the next episode and know that most of singers cannot help but obliviously sing off-key.

Other Reading of Interest:

Tone Deafness – Scientific American

The amusic brain – BRAIN: A Journal of Neurology

The neuroscientist, Rodrigo Quian Quiroga, attained renowned status after discovering a particular type of neuron that fired in an ‘abstract’ manner to pictures of different individuals, allowing for some predictive value of whom the person was looking at from a data of their neuronal firing. Fascinated with human perception, he teamed up with well-known Argentinean artist Mariano Molina to study the mind’s perception of art, particularly in juxtaposition to its perception of regular photos and individuals. Molina will spend five months working in the lab, learning about how perception works from a scientific viewpoint. In turn, Quiroga will get a look at perception through an artist’s frame.

Molina has discovered that many of his pieces of art intuit unconscious principles of perception that science had previously  identified. Consider one of Molina’s paintings: “The Center of Gaze.” Staring into it, one’s eyes are immediately drawn to the center. Center? How do I know that’s the center? At least, that would be the afterthought of one with a normal sense of perception. Upon further study, conscious reflection dwells on the “how” behind what the eye has intuited. This process that an individual feels within herself, the ex post facto rationalization of a quick and thoughtless, yet insightful, perception is akin to the methodology of the project itself.

Molina will complete a dozen pieces of art within a five month period, helping to draw insight into perceptual processes intuited by the artist. Molina believes that his artistic ability will also benefit from the scientific understanding of perception. Scheduled to begin in November, the project is hoped to bring scientific knowledge as well as an enriched appreciation for art, and encourage communication between the sciences and the arts that is of mutual benefit.

How Do We Perceive Art?  Artist in Residence to Work Alongside Neuroscience Research Lab -Univ. Leicester