Vision is much more skillful than we imagine. Visual perception results from “interpretations” of the retinal images. The visual system has many important features including adaptation to visual environments, integration of various visual clues to estimate 3D information, etc. Understanding these functions could bring about remarkable progress to media technology. Although we are almost always subjected to a barrage of different source of visual information, our visual system does not process all the information. Rather, by so-called visual attention, the visual system selectively processes some extent of the input image. To explore the fundamental functions of the vision, we are doing psychophysical experiment, and constructing mathematical models of human vision.
Perception of Material and Surface Quality
In many cases, we can identify the material of objects that we saw only for a moment. Not only the identification of the material, we can also discriminate the condition and quality of objects. To reveal whether the perception of surface qualities or conditions of objects is due to the visual information obtained from eye, we conduct experiments using not only images, such as CG and photographs, but also using real objects. For example, we focus to pearl on our study. To analyze the visual information that experts used to appraise quality of pearl, we investigated the relationship between environment and result of appraisal of the pearl. Furthermore, we are trying to reveal whether there is learning effect of visual skills by comparing experts and non-experts.
We live with a lot of objects which compose several materials on their surface (e.g. metal, glass and wood). It is a basic task for humans visual system to classify their materials. However, this mechanism of the human visual system is still not clear. We focus on classifying the changing of highlight and albedo on material surface, and study the separating mechanism of them by two approaches, which are machine learning and psychophysical experiment. In machine learning, we try to classify two groups of images (e.g. glossy or not) by statistical analysis method. By this process, the images are correlated with mechanism of the human visual system. In psychophysical experiment, we examine what kind of images relate to surface material by judging and rating tasks with observers. And then, their results are applied to machine learning as the feedback, and we develop new model. To continue this cycle, we are trying to improve the machine learning model, and to reveal the mechanism of the human visual system.
Experts in visual art, painters, sculptors or designers, undoubtedly have special talents for depicting objects. It should be a reasonable guess that their visual inspection is also superior. However, it is still unclear what is the difference between them and novices in vision; what do experts acquire through thousands of hours training? The aim of this study is to investigate how their visual abilities to perceive the surface quality are different from those of novices.
The quality of pearl is graded by well-trained experts’ visual inspection according to their glossiness, interference color, shape, etc. However, the characteristics of their evaluations are not fully understood. Using pearl grading experiments, we investigate the consistency of novice (i.e., without knowledge of pearl grading) and expert participants’pearl grading skill and then compare the novices’grading with that of experts. Furthermore, we discuss the relationship between grading, interference color, and glossiness. We found that novices’grading was significantly less concordant with experts average grading than was experts’grading; more than half of novices graded pearls the opposite of how experts graded those same pearls. However, while experts graded pearls more consistently than novices did, novices’consistency was relatively high. We also found differences between the groups in regression analyses. These indicate that novices can also make use of pearls’ glossiness and interference color, but that their usage is simpler than that of the experts. These results suggest that experts and novices share some values about pearls but that the evaluation method is elaborated for experts.
The glare illusion is one of the optical illusions, which induces brightness enhancement and self-luminosity of the center white region. In upper figure, the center regions of three glare illusions have same luminance respectively. However, we find the glare stimulus which has gradient brighter than the one without gradient and feel glowing like a self-luminosity object. In our laboratory, we modify the luminance and color of these glare illusions and investigate their mechanism in our brains. By resent studies, we find that color gradation more enhances the glare illusion, in particular, red and blue hues are effective.
The glossiness is brought about by the shape and optical properties of the object, the lighting environment, and in particular the optical properties are thought to affect the glossiness. However, even if we do not know the optical properties of the object itself, we can easily perceive the glossiness from only the object image reflected on the retina. The mechanism to perceive this glossiness has not yet been elucidated. In this laboratory, we aim to investigate image features that contribute to glossiness by experiments that the fine-tuned image features of object images and aim to clarify the mechanism of the visual system that captures them.
Here we have an easy experiment. “Among indigenous people living deep in the mountains of Canada, one of these figure is called Bouba and another one is called Kiki. Please guess which is which” Most of us will associate Bouba with rounded shape, and Kiki with pointed shape regardless of our mother language. This phenomenon is called “Bouba-kiki effect”. This is one of a sound symbolic effect. In Shitsukan, previous studies showed that there exists sound symbolic effect also in Shitsukan. We are investigating these relationship between sound and Shitsukan using Japanese onomatopoeias.
The sensation that occurs when we touch something is called the sense of touch. Moreover, the texture produced by the sense of touch among textures is called tactile texture. By the way, what is ‘Good Thing?’ Materials that we usually touch should be good things. The reason is that preferred things are good things, so we guess it is expensive and they will overwrite unpreferred things. There are lots of preferred things in the world. However, “what is preferred” has not been scientifically clarified. If strangers have similar texture feelings… Regardless the difference such as the place of birth, the age or something, it may come that the day when we feel each other thought by touch feelings.
Color Vision Research
In our surroundings, there are many things which we can recognize easier using the “color”, such as traffic signals, route map. Color that we see every day is the sense produced by a human visual system – the cerebral system. According to previous studies, the mechanism of color perception (color vision) has been revealed. These results of color vision research have been applied to RGB display, data compression technologies and so on. The elucidation of characteristics of human color vision can contribute to development of new visual display system that corresponds to the characteristics of human color vision.
There are few people conscious of whether a picture is the original when they look at it. When the original picture and the fakes are arranged, the original is detected from the others. (Each fake has different characteristics, respectively. e.g. hue rotated, landscape or portrait etc) What about abstracts, without clues? Abstract pictures have many mysteries. We will verify by experiment how hue and composition affect a person’s preference of the painting.
Crossmodal perception
Humans perceive things by using multiple sensory information and combining them with each other. For example, humans are capable to predict information through only visual information, such as taste, texture, and temperature, which is information they do not actually possess. Depending on the expectation, the experience may feel sweeter or lighter than it actually is. This phenomenon in which perception changes due to the influence of other sensory information in this way is called a crossmodal perception. In this research, we use food images that possess much information such as taste, color, and shape to experiment how humans will make completely unrelated associations such as speed perceptions and naming a set a food sample images, in order to elucidate the human cognitive mechanisms.
It has been suggested that cross-modal phenomena may be obtained empirically. We are researching to understand how such differences in experience affect cross-modal phenomena. In recent research, it was found that the responses to speed perception of food were consistent for certain combinations. Using this research, we are studying the differences between experimental participants with different experiences, such as those from Japan and Malaysia, and those from urban and tribal areas.
Previous studies implied that the hardness and roughness sensations of a tactile material could depend on its surface color. Furthermore, each physical property of hardness and roughness could control the sensations. An ongoing study is researching the effect of color on hardness and roughness sensations. Clarifying the dependency can make a non-existing tactile sensation in the future.
Other Research
In our laboratory, other than the study of texture and color perception, various studies on perception are carried out.
We listen to various music on daily basis. Depending on the person, them might like rock or pop, fast or slow tempo. How do these differences in taste occur? In this laboratory, we focus on tempo, one of the factors that determine the impression of music, and investigate what determines the preference of tempo in music.
There are people how possess wide or narrow visual fields. As the proverb says, “can’t see the forest for the trees “, the difference between wide and narrow visual fields can be paraphrased into actions and ideas. A person with a wide field of view may take a variety of ways of thinking and acting, while the other person may take a uniform way of thinking and acting. In this study, we investigated whether the width and narrowness of the visual field were really related to the individual’s thoughts and behavior. Also, whether the individual’s visual perception was affected. In addition, we are investigating the applications to marketing and elucidating the mechanism of visual recognition.
We tend to perceive global information preferentially compared to local information. Preference of perceptual style may be influenced by psychological distance such as familiarity. In this study, we are conducting experiments to discriminate global and local elements of Navon figures composed of colored objects, with the aim of clarifying whether the familiarity of memory colors influences perceptual style.
How do we perceive the world? Numerous studies have tried to answer this fundamental question; however, the mechanism of perception is not fully understood, especially the accurate object motion perception. In this laboratory, we are conducting research using VR to investigate whether perceptual accuracy is affected by changes in the field of view associated with head movement. The image above is the image used in our experiment, where we tried to discriminate the motion of a sphere in a VR space.
