What is the most interesting thing you learned this semester?

After taking this class of Perception, I have gained a tremendous amount of information about our senses and the world around us. I was not aware of how complex this process truly is. We were able to learn deeply about our five senses and the way we use them to perceive the world around us. After performing several mini-day experiments for our papers, I also go an opportunity to truly appreciate the importance of my senses. I remember doing the experiment for our first paper – about realizing the value of the sense of touch. At the end of the day I immediately came upon to the conclusion that touch is one of the earliest and most important senses in our body. With the ability to feel the sensation of touch, we are able to keep in “touch” in with the rest of our environment. The touch receptors in our body send electrical impulses to the brain thorough the nerve fibers. This information is further processed and analyzed in the brain, which then signals the rest of the body. The ability to feel pain, texture, shape or identity of an object is derived from this sense of touch. Without the ability to feel touch, I found myself struggling with simple tasks in life and had to rely on my other senses to get a better understanding of the world around me.  I was obligated to compensate for a poor sense of touch by relying heavily on my other senses. Under normal circumstances, we tend to forget the usage of the sense of touch in everything we do in life. Without this sense, we could possibly lose touch with the environment and the world around us. Even though I was truly intrigued with the importance of this sense of touch, I know that if I could never live without my sense of vision.

According to Professor Boucher, vision is the sense “that we take most for granted, and the one that we miss the most when we suddenly are without a keen sense of sight”. This statement had made a difference in my understanding of the visual world and has definitely convinced me how crucial vision is in our everyday experience. However, more importantly, even though we are able to see things visually, it’s the art of recognizing the objects is what is crucial to our understanding of the world. The concepts and theories behind object and face recognition is definitely one of the most interesting facts that I learned in this class. We recognize objects everyday in our life and we do this with very little effort and conscious. I was definitely amazed by the mechanisms that are involved behind this area of perception.

Several theories are involved behind object recognition. According to our textbook, Biederman proposed the theory of recognition by components in which he explains that when people first look at an object, they create a rough sketch in their head on the basis of the shape of the object. He proposes that the visual system extracts geometric icons or geons (picture above) and that is how we identify objects. His theory depicts two important properties – he claims that geons can potentially be distinguished from one another from any viewing perspective. The representations of objects are stored in the brain as structural depictions. He also states that when even when the random parts are erased from the geon, the rest will almost always remain recognizable. However, this theory was only accountable for the primal recognition of the objects because a higher level processing would involve more information about the objects including the spatial recognition, size, color, texture, and position of the object relative to its surroundings.

So what happens when we see an object again? How are we able to recognize the same object over and over? The neurons in the region of the IT cortex participate in recognition of objects and faces. The neurons in this area exhibit complex selectivity and some only respond to specific objects. Blake explains how IT neurons have large receptive fields, which means that the neurons will respond to an object that appears anywhere within a large region of the visual field. What I thought was most interesting in this area of research was also the ability to recognize faces. Of all the objects we are able to recognize in our everyday life, we are forced to look at thousands of faces be able to recognize them. A theory that explains this effect is the face inversion theory. Face processing is also referred to as holistic processing, the processing of information beyond the individual parts of the object, which means that faces are processed as a whole rather than in individual parts. According to Blake, in the textbook, we are able to process faces as global configurations, which leads us to be unable to just attend to one part of the face. In the above figure, it is more difficult to recognize faces when the contrast has been reversed as this distortion in contrast disrupts the facial cues we use to recognize faces. In class, we also learned about the six basic types of emotions found in all ages and cultures including sadness, happiness, anger, fear, surprise and disgust. We also learned about how an angry face stands out in a crowd of angry faces. I thought this was quite interesting and possibly true from an evolutionary point of view. The book also states the same reasoning, as it is probably important to recognize a potential enemy among friends than it is to detect a friend among a group of enemies.

After learning the various concepts of perception and our five senses in the class, I am much more aware of the complex processes involved in our everyday life. I was truly intrigued by the process of object recognition and face recognition. This has truly changed by perspective on the importance of our senses because even though vision is one sense that we definitely take for granted in our everyday lives, we also take the idea of this concept for granted. We would not be able to function without this processing; as even if we could see objects with our vision, not being able to recognize the various objects or faces would cut us off from the aspects of life.

Motion perception is an integral part of our life. Without motion perception, we would not be able to perceive the world around us in a way that it is supposed to be perceived. I cant even imagine living in a world without motion perception. As I researched more about this topic, I came across a study that detects how motion is perceived in people with autism. The topic of autism is very close to my heart as I have done a lot of research about it and have also worked with autistic kids before. Its always interesting to see the world from a different perspective and the way they perceive the world in a way that we cant. Autism is a brain developmental disorder, which impairs perception of the world as well as social and behavioral interactions. In this research, the study tests motion sensitivity for people with autism and people with normal perception. The study states “the majority of the evidence demonstrating atypical visual processing in autism is related to an enhanced performance on visuospatial tasks implicating the detection or matching of simple geometric patterns among a more complex visual field. Accordingly, individuals with autism show an enhanced performance on the block design test in reproducing impossible figures and in discriminating elementary visual information, within a visual search paradigm”. People with autism also demonstrate difficulty in perceiving faces and facial expressions. The study tested the ability of autistic people to assess visual motion perception of various objects. The motion patterns that were tested in the study were either of the first or second order – luminance defined or texture defined. The results of the study show that motion perception of autistic people was similar to normal perceptive people in the first order but not in the second order.

Colors play an important in the world we live in. From traffic lights to the bright yellow sunlight, colors have the ability to persuade us in every way possible. Certain colors can affect our thinking in a positive or a negative way, while other colors can affect us mentally – relax us, irritate us, make us happy or make us sad. When I look around my room, I notice the presence of color green all around me. From my green bed sheets to green curtains to green candles, the presence of green in the room is somehow quite soothing. The presence of green is also evident in the food I eat – from green apples to green broccoli to green spinach- the existence of green makes every thing seem healthy and lively. The significance of colors also varies from culture to culture. As a Hindu, I have grown up learning about the importance of color red. Red is prominent in almost every Hindu ritual and is of utmost significance. A red mark on the forehead is a sign of a blessing and is used in all ritual ceremonies. Red is the color a bride is supposed to wear during weddings as it symbolized prosperity and happiness. Instead of a wedding ring, the presence of red powder on a woman’s hair parting is the symbol of her marriage. The red powder is also used in the temples for religious ceremonies. The pictures below show the presence of color red in every aspect of the culture.

As I starting thinking about the presence of colors and its affects on our everyday lives, I couldn’t help but wonder about the idea of color perception. Do we perceive colors differently from one another? What about the difference between a child’s perception of a certain color versus the perception of an older person? During my research on this particular topic, I came across this study conducted by British and American researchers. The research is a study of infants and adults’ perception of different colors. During the study, they found that at times the right visual was activated whereas sometimes the left visual field was activated. The left visual field connects to the pre-linguistic right hemisphere of the brain whereas the right visual field was connected to the brain’s left hemisphere, the area where language processing takes place. The study also found that infants performed better when the targets appeared in their left visual field (right hemisphere) whereas the adults performed better when the targets appeared in their right visual field ( left hemisphere). So what does language perception has to do with color perception? This study also raises a lot of other questions and asks to wonder whether infants and adults perceive the same color differently?

So I guess in the end, its safe to say that color really does matter!

How does the nature versus nurture debate come into play in the development of a normal visual system?

The debate of nature v. nurture has been in question for quite some time now. Scientists have been questioning the fact whether our behaviors are a result of our biological composition or are we being environmentally influenced? This topic made me wonder about this ongoing debate and whether if there is a right or a wrong answer in this case. The question by Professor Boucher asks us to analyze us as to how the debate of nature v. nurture come into play in the development of a normal visual system. As I decided to do some more research on this particular topic, I came across the research done by David Ferster.

According to Ferster, in order to study the profound effects of nurture and the environment on early development, neuroscientists focus on models that are easy to manipulate and when the neural changes are easy to detect. Fester also states that, “the most intensely studied model of environmentally driven neural plasticity is that of ocular dominance columns in the developing mammalian visual cortex”. According to the research, the inputs from the relay cells from one eye are packed in the visual cortex into “nearly parallel, stripelike regions or columns”. The inputs from both eyes start out by overlapping with each other at birth and eventually separate into “ocular dominance bands” throughout the next several weeks. This phenomenon is important for the visual experience because during early development, when one eye is used more than the other, the ocular dominance for that eye is greater than for the other eye, which would have a smaller dominance. The author proposes one explanation for this phenomenon when he says: “One model, for example, relies on Hebbian rules, a winner-take-all competition in which synaptic inputs that most strongly activate a cortical neuron are strengthened at the expense of weaker ones…the strong get stronger and the weak get weaker. Through this process, even small, random imbalances in the overlapping input from the two eyes get amplified to the point that the weaker eye’s input fades entirely and each cortical cell’s input becomes predominantly monocular. The effects of eye closure are now easily explained: The closed eye’s inputs are reduced in activity and can no longer compete effectively with their counterparts from the other eye.”

This was quite interesting because even with the technology and the tremendous amount of research that has been done, we are still unable to propose to the solution to this debate. In the end of the article, the author states how “we may indeed learn not only how genes shape behavior directly, but also how the environment shapes behavior through its effect on gene expression”.

As discussed in class, the work done by Dr. Isabel Gauthier is definitely remarkable. She is a great asset to the Vanderbilt community and has done a tremendous amount of research in visual object recognition. I was lucky enough to have a chance to work in her lab and have been working with her graduate student for the past year now. I have also participated in several of the face and object recognition studies dealing with greebles.

Previous studies in the lab have shown that faces are processed differently than objects. Face processing is also referred to as holistic processing, the processing of information beyond the individual parts of the object, which means that faces are processed as a whole rather than in individual parts. In the experiment done last semester with my graduate student, the subjects were asked to match either the tops or bottoms of Greebles and faces, while ignoring the other part. The studies show that when subjects study the misaligned Greeble, it was difficult to ignore the irrelevant part of the test Greeble. This inability to study the misaligned Greeble led to a congruency effect because studying a missligned greeble causes attention to be spread out in space, it is more difficult to then focus on just one part of the test Greeble. The bottom figure is an overview of the experiment and demonstrates the format of the experiment.

The results of the experiment show that viewing the aligned pink Greeble does not affect the performance with the green Greeble that follows it. However, during the study of the two Greeble matching tasks, it is expected that viewing a misaligned pink study Greeble would decrease the ability to ignore one half of the green test Greeble that follows it, even though the pink Greeble is irrelevant to the green task. The results of this experiment suggest that processing an aligned face induces holistic processing for the subsequently presented Greeble, resulting in a congruency effect. During the single face matching tasks, the results show that if the test face if aligned it is more difficult to ignore the irrelevant part of the test face. This inability to accurately judge the faces is due to the fact that faces are processed holistically. Studies have proven that faces are processed as one object as opposed to distinct individual parts. After the experiment, we expect that viewing an aligned face prior to viewing the green Greeble will decrease the ability to ignore one half of the green test Greeble that follows it, even though the face is irrelevant to the Greeble matching task. However, when studying the misaligned face, the performance of the Green Greeble will not be affected.

*The above experiment was conducted in Gauthier’s lab in collaboration with Jennifer Richler, a graduate student for Dr. Isabel Gauthier.

Vision is a crucial part of our everyday lives and it also one of the most important senses and the one we take for granted. Do you know what its like to experience a day without the sense of vision? Would you be able to handles the uneasiness with faced with a day with blurred vision? After experiencing a whole day with my monocular sense of vision, I decided to research about the other types of visual problems and their relation with other disorders. One of the visual disorders that I have been familiar with is diplopia. An old family friend of mine suffers from this disorder and has been seeking treatment for a while now. Diplopia is also commonly known as double vision and is the “simultaneous perception of two images of a single object”, according to Wikipedia. This disorder can monocular or binocular, which means that monocular diplopia is usually active when only one of the eye is open whereas binocular diplopia is the result of misalignment of both of the eyes and disappears when either of the eye is closed. Binocular diplopia can be a cause of several things but mainly results from the misalignment of both of the eyes on different objects. When the brain perceives two different images, it causes the eye to see two different visions of the same object and sometimes causes one of the images to be blurrier than the other. The disorder of double vision can usually be treated with eye muscle surgery or vision therapy. Here are some visuals of diplopia.

As I researched more about the procedures of vision therapy and relationship with other disorders, I was appalled by the amount of research that has been on how vision is related to several other disorders. One research that caught by eye is the study done by Roger Johnson and The New York State Optometric Association Vision Screening Battery (NYSOA) as they tried to find how attention deficit disorder (ADD), attention deficit hyperactivity disorder (ADHD), dyslexia or dyslexic, or oppositional-defiant behavior, is related to vision problems. In the study, 81 elementary, middle and high school students were tested in order to rule out the possibility of vision difficulties leading up to these disorders. The study also revealed that students who were at risk for behavioral or academic problems, scored significantly lower on vision tracking abilities. In fact, a great amount of studies have shown on how a lot of behavioral disorders, especially ADD and ADHD, are mistakes for actual vision problems. This article by DB Granet also shows how plenty of children are being treated for behavioral problems, when in fact the vision problems are not being treated.

Did you know that one in every 12 men has at least some kind of color perception problems? As I sit here and write this blog about the concept of vision and perception, I decided to research about the concept of colorblindness. According to Wikipedia, colorblindness is the “inability to perceive differences between some of the colors”. People are not able to tell the difference in some of the colors due to color vision deficiency but it does not mean that a person only sees black and white. Colorblindness is usually a genetic disorder and is passed down in the family. It results from the deficiency of one of the photoreceptors located in the retina. The retina contains cones for three different colors including red, blue, and green. Colorblindness is the result when one of these photoreceptors is missing. My first cousin, who suffers from this disorder, is unable to tell the difference between red and green. I wonder how weird would it be to not be able to tell the difference between different sorts of colors. I consider myself a very colorful person- my closet is a collection of rainbow colors. I would not be able to fully express myself without being able to tell the difference between colors of life. As I researched more about this topic, I found some really interesting articles.

The researchers at Medical College of Wisconsin conducted experiments about how colorblindness can eventually be cured by gene therapy. In the experiments, researchers inject the normal genes that are missing during colorblindness deficiency. According to the researcher, the “eye has an advantage of being a closed vessel so that gene therapy can be targeted very quickly”. The researchers also used the concept of retrovirus in which they inject the DNA, which “makes the human cone pigment”. The virus eventually attaches to the cell and replicates the pigment.

So is there an advantage to colorblindness? As I tried to find advantage to colorblindness, I came across an article about how the primatologists at University of Calgary found out how color blind capuchins are able to detect camouflaged insects than the “individuals with broader vision”. The study also talks about how because of the reduction in colors in colorblindness, the difference in texture and brightness is more obvious and therefore, they are able to distinguish between the camouflaged. This study was quite interesting as it showed some type of advantage to this deficiency, which makes me wonder if we can put it to use as humans.

Do you know if you’re colorblind? Check it out here!

As I started thinking about the idea of an optical illusion, I decided to find out what the actual definition was. According to Wikipedia, an optical illusion is “characterized visually perceived images that are deceptive or misleading”. Optical illusions work in several ways and can be used through the distortion of color, shape, texture, movement etc. I think its very interesting how our eye can perceive only a certain amount of information at a given time while our brain processes and makes meaning of the situation. An optical allusion is the blend of our perception and vision. Our brain processes information based on the external stimuli and based on our experiences. 

One of my favorite illusions is an image of the two-stroke motion. The image contains two different patters from a certain image, which gives the image of a forward action. According to the author, the image works because of the positive and negative effects. “The dramatic effect of the blank ISI is due to the visual system’s temporal response – how it responds to sudden changes in illumination. In bright conditions the response to a sudden change shows an initial positive phase followed by a brief negative phase. The latter can be viewed as creating a negative neural image of whatever preceded the change. So during the brief ISI, a negative neural image of frame-2 is created in the visual system. This negative response combines with the positive response created by frame-1 to evoke apparent motion. The combination of positive and negative images in motion sequences is already known to produce reversed apparent motion, as can be seen in four-stroke motion”. The forward motion is created by inserting a blank image in between the two images known as the black inter-stimulus interval (ISI). As the image is switched from the first to the second one, a forward motion is created and as the image is switched from the second to the first one, a backward motion is created. This was quite interesting to me as it showed how our brain and our senses work in a unique way to create these optical illusions.

Did you know that humans are capable of distinguish between thousands of smells? After the class lecture on Wednesday, I started thinking about the smelly business of life and how we are being influenced by the power of smell all around us. As for me, I am not sure if I have a particular favorite smell but I definitely rely on odors throughout the whole day. I love waking up and smelling a freshly brewed cup of coffee or stopping by Starbucks, on my way to class, and picking up a hot cup of white chocolate mocha. Our sense of smell is quite powerful and has the capability of arousing strong emotions or memories. As for me, I know that I absolutely cannot live without scented candles esp. Yankee candles. I constantly use them in my room throughout the year. I also love the smell of laundry out of the dryer, the smell of baked chocolate chip cookies, the smell of freshly cut grass and the smell of my favorite perfume. Each of these scents relates back to some kind of memory and bring upon a lot of emotions. For example, the smell of laundry always reminds me of back home and the chaos of Sunday mornings. The smell of chocolate chip cookies remind me of my grandmother’s special recipe. So what exactly is the relationship between in what we smell and how we feel.? As I started to research more about this idea, I came across an article from the NewsScientist about the direct link of smell to our emotions. The article states that, “when odour information travels from the olfactory bulb and reaches the primary olfactory cortex it activates the limbic system at an earlier stage of processing than do the other senses”, which in turn triggers an emotional response in mammals.

The article also talks about a study conducted with male and female consumers. They eventually discovered that when female scents were used, sales of women’s clothes doubled and vice versa when male scents were used. I thought this was quite interesting as it shows how powerful our sense of smell is and the effects it can have on an individual. This only makes us realize how we are being influenced by the sense of smell all around us. From electronics stores to car dealerships to Starbucks, consumers are being manipulated by powerful smells and retailers are taking full advantage of this fact. In recent news on CNN, Wal-Mart is soon to offer “scented” DVDs, which contain electronic scent wafers. The article also talks about the “run and sniff” versions of advertisement in newspaper journals. Gas stations are also using technology to spread the “coffee aroma” all around in order to boost their sales. These retail companies are taking full advantage of the manipulation of smell and believe that these additional added aromas can help sell their products. These studies prove that smell definitely influences our buying behavior one way or another.

 January 26, 2008.

As I am sitting here in the Stevenson library studying Chapter 13 from our Perception textbook, I cant help but be drawn to this idea of the Gate control theory of pain. According to our textbook, this theory is a view that perception of pain involves the interplay between two fiber groups, one that can modulate the strength of signals in the other. It states that physical pain is not a direct result of the activation of pain receptor neurons but how our thoughts and emotions influence the intensity of the pain. So, if this in fact true, if we could somehow manage to control our thoughts and emotion, and “close” the gate of pain, could we manage to find a cure of several chronic pain illnesses? I decided to google this idea and was fascinated by the amount of research that has been done regarding this issue. One article that caught my attention is a study done by Columbia researchers and how they might have discovered an on-off switch for chronic pain. According to the study, in order for chronic pain to endure a master switch must be turned on inside the peripheral neurons and this “master switch” is an enzyme called protein kinase G (PKG). The researchers found that “upon injury or inflammation, the PKG is turned on and activated. Once activated, these molecules set off other processes that generate the pain messages. As long as the PKG remains on, the pain persists. Conversely, turning the PKG off relieves the pain, making PKG an excellent target for therapy”. The study also talks about how nearly half of the people who suffer from chronic pain do no consult a physician in their lifetime despite the effects of pain on their lives. This study was quite interesting as it makes me wonder as to why people would not want to be treated for their pain. Are they suffering from the disease of pain or is it a result of a bigger problem? So how can we really categorize the concept of pain itself. All the research and studies done are focused on finding a cure for the diseases and therefore reducing the pain. We believe that if we can eliminate the possibility of a disease, the pain itself would vanish. So why is it that pain is treated as a symptom of a bigger problem rather than being the problem itself. Can pain be the leading disease rather than just being caused by one? Can pain just be the symptom of pain?