It does so in an instant: as in a flash one glance, an opening of the eyes, discloses a world of co-present qualities spread out in space, ranged in depth, continuing into indefinite distance […] Jonas, , p. Put differently, vision as a distant sense has a qualitatively different function than touch as a proximal sense.
This qualitative difference renders conclusions about the absolute importance of a given sensory modality almost impossible. Thus, although smell may play a rather minor role in everyday life, it becomes extremely important in potentially harmful or even life-threatening situations, such as determining whether some food is rotten, detecting a gas leak or smelling fire. In short, the degree to which vision dominates the research on the different sensory modalities cannot simply be explained by claiming that vision is the most important modality.
As it will turn out in the next section, the same applies to the complexity argument. The complexity argument was based on the assumption that a large part of the human brain is specialized on visual processing while relatively small parts are specialized on processing information from other sensory modalitities.
This assumption has been questioned in recent years: Instead of regarding the senses as strictly separated entities, it has become quite common to accept that they often interact and influence each other, which is also mirrored in the neural underpinnings for reviews see e.
Interestingly, multisensory integration does not only occur in the later brain regions in the temporal and frontal cortices, but also in earlier brain regions and even in the primary sensory cortices.
Moreover, brain regions previously believed to be visual by nature are used during Braille reading e. As multisensory processing appears to be the rule rather than the exception, claiming that a large part of the human brain is exclusively specialized for processing visual information seems at least debatable see e. However, this line of reasoning is not the only way to question the complexity argument: Why should the size of brain regions specialized on processing information from a certain modality be the only criterion at all, when it comes to determining complexity?
One could also take into account the number of different receptor cells, for instance: While humans have only two major classes of photoreceptor cells rods and three kinds of cones , they possess several hundred different kinds of olfactory receptor cells Axel, ; Glusman et al. Alternatively, remember that the skin is the largest sensory organ of the human body, accounting for more than a tenth of total body weight Montagu, ; Field, ; Martini and Nath, Again, these examples are not meant to claim that vision is definitely not the most complex modality, but rather that there are various ways of defining complexity for an attempt to distinguish different meanings of complexity in the chemical senses, see Spence and Wang, Moreover, no definition presented here seems to provide clear evidence that vision is beyond any doubt the most complex sensory modality.
As both the importance and complexity argument are insufficient for explaining the degree to which vision dominates the research on the different sensory modalities, it seems necessary to look for other possible explanations. Here, I present and discuss two additional explanations which can help illuminating the bias toward vision in research.
The methodological-structural explanation claims that research on vision is often easier than research on other modalities and that this the result of an initial bias toward vision that reinforces itself; the cultural explanation carves out that the dominance of the visual is not a historical constant, but rather a result of the way Western societies are designed. Imagine having to set up an experiment that investigates long-term memory for everyday objects. If you decided to present the objects visually on a computer screen, your task would be straightforward: Use your favorite search engine and collect as many images of as many different objects as possible.
Instead, you may also refer to one of the publicly available databases, offering thousands and thousands of images see e. If you decided to present the objects haptically , your task would be much harder: Even if you had a list containing the names of all objects used in a previous study as well as photos of these objects e. And the struggle continues: The objects gathered for haptic presentation will occupy much more space than the images of objects stored on your hard drive.
Even setting up the actual experiment is easier when working with images presented on a computer screen, as with all programs designed for creating experiments, many potential methodological flaws are easy to avoid. The duration of the stimulus presentation can be determined precisely, counterbalancing within and between participants is normally achieved with a couple of mouse clicks or lines of code , and the responses of the participants are automatically recorded and coded as correct or false.
All these things become vastly more difficult when doing the same experiment involving haptic exploration, as the experimenter has to navigate carefully between the objects a wine glass is fragile, the image of a wine glass is not , keep track of the objects that were already presented, make sure that the participants do not explore the objects too long, and so on. In short, while there is a lot of off-the-shelf technology available for studying vision, this is not the case for other sensory modalities such as touch see e.
However, this conclusion is not the end of the methodological-structural explanation. Instead, one could ask further: What could be the reason that the available technology is better suited for studying vision than the other modalities?
There are two possible answers to this question. First, one may argue that vision is by nature easier or that the other senses are by nature harder to investigate. In contrast, it seems hard to imagine how there could be off-the shelf technology for studying the chemical senses, for instance: Although researchers have tried to, no one has yet found a digital way of stimulating the chemical senses, which would be an important precondition for setting up standardized and easily controllable experiments see Spence et al.
The same can be said about haptic long-term memory: Whoever wants to study the haptic exploration of everyday objects will have to collect the respective objects. There seems to be no way around this. Even if there is a way around this in some cases, however, the tools developed to study other senses such as touch see e.
Rather than demonstrating that present-day technology used to investigate haptics is equal to the technology to investigate vision, these efforts to create adequate instruments in the absence of an established technology remind of the situation at the end of the 19th century, when the first experimental psychological laboratories were founded see e. At that time, creating tools for research on vision was a laborious process. Hence, one can get the impression that the development of haptic technology lags behind in time.
Thus, one could hypothesize that instead of or at least in addition to being naturally better suited for investigation, vision may have had an arbitrary advantage in the beginning of experimental research and that this initial advantage has perpetuated and possibly even reinforced itself since then. Classen et al. Expressed differently, funding for research into vision might be much easier to obtain than funding for smell or touch.
This might in turn bias researches toward doing research on vision as it is easier to get funding, and so on. There are various possible reasons why the study of vision may have had an advantage in the beginning of experimental research: 1 researchers at the time may have had personal reasons to study vision instead of other modalities e.
In conclusion, the methodological-structural explanation claims that there is more research on vision because the available, present-day technology is better suited for studying vision than for studying other modalities. Although one may claim that vision is easier to investigate by nature, it seems quite likely that this claim and thus the technological advantage for vision is at least partially the result of a Matthew effect: As there is more research on and easier accessible technology for vision compared to other modalities today, there will most likely be more research on and technology for vision tomorrow.
In addition to the self-perpetuating process proposed by the Matthew effect, there may also be a cultural explanation for the bias toward vision. At first sight, one may think of visual dominance as a cultural constant that can be traced back to antiquity for a history of the senses, see e.
In a similar manner, Aristotle creates a ranking of the senses, putting vision first, followed by hearing, smell, taste, and touch. Although subsequent philosophers did not agree with the classical Aristotelian hierarchy in every respect, vision is almost always ranked as the highest sense in Western societies throughout the medieval ages up until today.
In this context, it is especially interesting that the study on the frequency of words referring to the different sensory modalities quoted above, did not only find an overall higher frequency of visual words in the investigated English corpora. When looking at the average frequencies for each modality based on the ten most exclusive words per modality, there was hardly any change in the past years see Winter et al.
Although the Aristotelian hierarchy has undeniably had a huge influence on the conceptualizations of generation upon generation of philosophers and although one may argue that there is a long history of visual dominance, matters become vastly more complicated when taking a closer look at the available sources.
Thus, one could claim that the hierarchy proclaimed by Aristotle was not meant to be interpreted that strictly after all. Second, it can be demonstrated that the dominance of the visual — supposedly already existing in the times of Aristotle — was less pronounced for a long time, that is, that the non-visual senses have lost ground against sight in the course of the past centuries.
Hence, rather than being a cultural constant, visual dominance turns out to be heavily influenced by human decision-making. I will illustrate this idea using three different examples. First, consider the shift from an oral, hearing-dominated to a written, sight-dominated culture e. Note, that this shift from hearing to sight arguably also changed interactions between people: The oral transmission of knowledge — and of literature, by the way — requires at least two people a teacher and a student; someone who is telling a story and someone who is listening to it ; in contrast, reading a book does not require any personal interaction — you can do it entirely on your own.
Second, take the decrease of the importance of smell. Moreover, the strength of the odor of a plant was associated with its presumed medical power: In order to protect themselves against epidemic diseases such as the plague, people in the medieval ages often carried a pomander with them, as they believed that strong scents are an antidote against the odors of illness which were considered to be the cause of infection.
This slowly changed from the 16th and even more so from the 18th century onward: As the belief in the healing power of scents faded away and as gardens were also cultivated for aesthetical and recreational reasons, visuals became increasingly more important.
In contrast to this hypothesis, it has been shown that the olfactory abilities of humans are in fact quite good.
Third, imagine walking through a modern museum exhibiting sculptures: You would probably not in your wildest dreams think of touching these sculptures — and if you did, security guards, alarms, not to-be-crossed lines on the floor or transparent cases around the sculptures would remind you immediately that art is not to be touched see Gallace and Spence, , for the few contemporary counterexamples.
Note, that remnants of these haptic worshipping traditions have survived until today: The right foot of the bronze statue of St. Peter in the St. As these three examples demonstrate, one can trace an ongoing shift toward vision throughout history. However, the bias toward vision may be even more pronounced in our present-day societies than ever before: Beginning with the invention of movies, cinema, and television and even more so in the face of the omnipresence of smartphones and computers, visual technologies increasingly regulate our daily lives:.
Modern life takes place onscreen. It is not just a part of everyday life, it is everyday life Mirzoeff, , p. To give one illustrative example, consider the now-common habit of taking a picture of your meal and of sharing it on social media before starting to eat. It has been hypothesized that this habit has profoundly changed the way restaurants are recommended.
This may ultimately lead chefs and restaurant owners to pay more attention to the visual arrangement of the food they serve, or even to prepare the food in a way that is going to look good on Instagram see e. More broadly speaking, paying attention to visual aspects seems crucial to achieve important goals in life such as finding a job or a partner as well as improving social relationships — just think of the importance of visuals when presenting oneself on an online dating website, sharing holiday pictures on social media or applying for a job with a well-designed resume.
Such a visual turn can supposedly have a double function: it can account for the dominance of the visual by emphasizing the importance of research on the topic and it can help to create both an appropriate methodology to investigate and appropriate theories to describe the visual turn. Overall, it seems that the dominance of the visual is not a cultural constant. It should not be forgotten, however, that everything that has been discussed so far primarily referred to — pre-modern, modern, and postmodern — Western cultures and societies.
As it will turn out, considering non-Western societies only confirms the ideas presented so far: The dominance of the visual is at least partially the result of human decision-making and should thus not be regarded as an unvarying historical constant. Two examples shall suffice to illustrate the enormous cross-cultural variability. First, a recent study has demonstrated that there is no universal hierarchy of the senses by investigating 20 different languages including three unrelated sign languages Majid et al.
The authors created stimulus sets for each of the five Aristotelian sensory modalities and asked their participants to describe them What color is this? What sound is this? Apart from the fact that smell is poorly coded in most languages, there was no common hierarchy of the senses. While English indeed seems to have a visual bias see the study by Winter et al. Second, let us examine one of the cultures for which sound seems to be more important than vision: the culture of the Songhay of Niger.
It is important to note, that for them, sound is not only important because like in any oral culture, knowledge is transmitted by spoken words, but because the sounds of the words themselves are believed to carry energy and power:. What can we learn from considering the cultural explanation regarding the question why there is so much more research on vision than on any other sensory modality? The answer is quite simple: Living in a visual society means living in a society placing high value on vision and comparably little value on the other senses — a tendency that is mirrored in the number of studies on vision.
Put differently, a society placing higher value on the other senses would probably develop more balanced research agendas i. All of our senses give us vital information about our surroundings, but the one we rely on most is vision. Accordingly, the physical apparatus for gathering visual information—the eye—and the brain circuits that process this information are more complex than corresponding systems for the other senses.
The brain devotes more space to vision than to all other senses combined. The eye is roughly spherical and about an inch in diameter. In the front, the cornea and lens focus light reflected from objects in the world onto the retina in the back of the eye.
The lens changes shape to allow us to see both near and far objects clearly. The retina contains nerve cells as well as a layer of million rods and cones, receptor cells that respond to light. Some react primarily to red, some to green, some to blue light. Cones function well only in reasonably bright light. Rods, which are more than times more light-sensitive, let us see in near darkness. Similarly, because rods greatly outnumber cones in outer areas of the retina, colors seem washed out in peripheral vision.
In both rods and cones, light initiates chemical reactions that activate neurotransmitters to generate nerve signals. Other cells in the retina gather and start to sort these signals and send them on their way, via the optic nerve, to the brain.
These signals carry the basic components of light, color, and shape—the sensation of vision. Interpreting this barrage of unstructured data as meaningful images—the people, places, and things that we recognize and react to as the visible world—requires a complex mental process called perception. Most of this processing takes place in the visual, or occipital, cortex, the rearmost part of the highly evolved outer layer of the brain. Signals from the eye arrive here after passing through the thalamus, a kind of switching station for all the senses.
In the visual cortex, this information is sent on to some 30 different regions, each specializing in its own aspect of sight. The underside of the cortex organizes visual signals into shapes and colors; signals going to its upper part register location and motion. One region specializes in faces; another, places. Vision has a specific sensory system, the visual system. Related Stories.
Depression Affects Visual Perception Mar. A study conducted at the University of Helsinki found that in depressed patients, the processing of visual perceptions is also The researchers isolated the functions of melanopsin cells and demonstrated A glare illusion is an optical illusion that Different attributes of visual perception are widely used in GUI design. Many designers apply Gestalt principles i. Human vision is an amazing ability; we are capable of interpreting our surroundings so as to interact safely and accurately with little conscious effort.
However, we are well attuned to nature and things that occur naturally in our environment, which has significant implications for design. Unless man-made products are attuned to, and support, human visual perception, the viewing experience suffers and there is significant potential that users will be unable to use your products quickly, safely, or without error.
For this reason, it is essential that we investigate how we see the world and why we see things in the way we do in order to know what we can do to ensure our products provide the best viewing experience possible. For those of us who are blessed with good eyesight, we seldom consider it.
Happily, getting to the bottom of the phenomena involved in visual perception is a lot less laborious, and perhaps infinitely more fascinating. During the course, we will first cover the basic anatomy of the human eye so as to understand how vision is formed.
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