Tetsuto Minami

Toyohashi University of Technology · Department of Computer Science and Engineering

Subjective brightness perception reportedly differs among the peripheral visual fields owing to lower- and higher-order cognition. However, there is still a lack of information associated with subjective brightness perception in the world-centered coordinates, not in the visual fields. In this study, we aimed to investigate the anisotropy of subjec...

As time plays a fundamental role in our social activities, scholars have studied temporal perception since the earliest days of experimental psychology. Since the 1960s, the ubiquity of color has been driving research on the potential effects of the colors red and blue on temporal perception and on its underlying mechanism. However, the results hav...

Visual-field (VF) anisotropy has been investigated in terms of spatial resolution of attention, spatial frequency, and semantic processing. Brightness perception has also been reported to vary between VFs. However, the influence of VF anisotropy on brightness perception using pupillometry has not been investigated. The present study measured partic...

This study investigates the influence of ambiguous sun and moon images on stimuli perception based on pupillometry. A random stimulus was presented in a few seconds, and another few seconds, as feedback, observers reported the stimulus was perceived as the moon or the sun. To overcome the lack of previous studies that have not been able to segregat...

Background As urban development toward smart cities continues in earnest, pedestrians’ chances of encountering autonomous mobile robots (AMRs) on the street increase. Although recent studies have discussed how humans avoid collisions with others when passing them, it is still unclear how they would avoid AMRs, which could be common on the streets s...

The relationships between posture and perception have already been investigated in several studies. However, it is still unclear how perceptual bias and experiential contexts of human perception affect observers’ perception when posture is changed. In this study, we hypothesized that a change in the perceptual probability caused by perceptual bias...

Recent studies have discovered that pupillary response changes depend on cognitive factors, such as subjective brightness caused by optical illusions and luminance. However, it remains unclear how the cognitive factor derived from the glossiness perception of object surfaces affects pupillary response. We investigated the relationship between gloss...

Color composition in paintings is a critical factor affecting observers’ aesthetic judgments. We examined observers’ preferences for the color composition of Japanese and Occidental paintings when their color gamut was rotated. In the experiment, observers were asked to select their preferred image from original and three hue-rotated images in a fo...

Laterality is a bias in which humans prefer one side over the other. Previous research has shown laterality in facial direction and facial aspects; right-facing faces are preferred over left-facing faces, indicating a rightward dominance. Right hemisphere is specialized for face recognition, and facial parts of a right-facing face are located on th...

The face pareidolia phenomenon, incorrect perception of something that is not a face as a face, affects human cognition and behavior. Although some face pareidolia studies focus on event-related potentials (ERPs) as the physiological indicator, most of them use stimuli uncontrolled context, spatial frequency, and contrast. The physiological respons...

There have been various studies on the effects of emotional visual processing on subsequent non-emotional auditory stimuli. A previous study with EEG has shown that responses to deviant sounds presented after presenting negative pictures collected more attentional resources than those for neutral pictures. To investigate such a compelling between e...

Temporal perception and the ability to precisely ascertain time duration are central to essentially all behaviors. Since stimulus magnitude is assumed to be positively related to the perceived duration from the early days of experimental psychology, most studies so far have assessed this effect by presenting stimuli with relatively different intens...

Recent researches revealed that the EEG component caused by the flickering visual stimulus, which is called steady-state visually evoked potential (SSVEP), might be a potential index for object recognition. This study examined whether SSVEP reflects different states during object recognition. In one trial, a binary image (BI), which is difficult to...

The importance of the English language has been increasing as various fields have become more globalized. When Japanese people try to acquire foreign language such as English, learners find it difficult to perceive speech-sounds such as the phonemes /l/ and /r/ that are absent in their native language (e.g., “light”/lάit/ and “right”/rάit/). Recent...

We hypothesized that a perceptually ambiguous or bistable object (Necker cube) can be more effectively biased to assume a point of view-from-above (VFA) than from below the object by cueing attention. Participants viewed a Necker cube in which one surface was temporarily shaded so as to prime a specific perspective on the cube. Subsequently, the st...

In daily life, our emotions are often elicited by a multimodal environment, mainly visual and auditory stimuli. Therefore, it is crucial to investigate the symmetrical characteristics of emotional responses to pictures and sounds. In this study, we aimed to elucidate the relationship of attentional states to emotional unimodal stimuli (pictures or...

It is widely known that reinforcement learning systems in the brain contribute to learning via interactions with the environment. These systems are capable of solving multidimensional problems, in which some dimensions are relevant to a reward, while others are not. To solve these problems, computational models use Bayesian learning, a strategy sup...

The glare illusion enhances the perceived brightness of a central white area surrounded by a luminance gradient, without any actual change in light intensity. In this study, we measured the varied brightness and neurophysiological responses of electroencephalography (EEG) and pupil size with the several luminance contrast patterns of the glare illu...

We hypothesized that pupil constrictions to the glare illusion, where converging luminance gradients subjectively enhance the perception of brightness, would be stronger for ‘blue’ than for other colors. Such an expectation was based on reflections about the ecology of vision, where the experience of dazzling light is common when one happens to loo...

The ability to track multiple objects is important for daily life activities such as driving, but it is subject to some restrictions. One limitation concerns the hemifields in which objects move. A previous study showed that when subjects were restricted to the use of one hemifield, both the maximum number of tracked objects and the tracking accura...

The change of facial color and expression reflects our mental or physical condition. Previous behavioral studies indicated that there is a strong interaction between facial color and expression perception. This study investigated the contribution of facial color to expression recognition in blur images with the measurement of behavior and pupillary...

Detecting others’ emotional states from their faces is an essential component of successful social interaction. However, the ability to perceive emotional expressions is reported to be modulated by a number of factors. We have previously found that facial color modulates the judgment of facial expression, while another study has shown that backgrou...

Insight refers to the sudden conscious shift in the perception of a situation following a period of unconscious processing. The present study aimed to investigate the implicit neural mechanisms underlying insight-based recognition, and to determine the association between these mechanisms and the extent of pupil dilation. Participants were presente...

Faces represent important information for social communication, because social information, such as face-color, expression, and gender, is obtained from faces. Therefore, individuals' tend to find faces unconsciously, even in objects. Why is face-likeness perceived in non-face objects? Previous event-related potential (ERP) studies showed that the...

Most people have experienced phenomenon where they perceive faces in the various non-face objects. This phenomenon is called “face pareidolia”. In the present study, we investigated face pareidolia using pupillary response. The pupillary response was suggested to be influenced by high-level cognition. Therefore, we predicted that change of pupil di...

This research aims to design an user interface for controlling a tele-operation robot by brain machine interface (BMI). In this research,we use a BMI based on Steady-State Visual Evoked Potentials (SSVEP). We carried out experiments to compare Support Vector Machine (SVM) and Multivariate Synchronization Index (MSI) for analysing SSVEP. Consequentl...

The probability of an event's occurrence affects event-related potentials (ERPs) on electroencephalograms. The relation between probability and potentials has been discussed by using a quantity called surprise that represents the self-information that humans receive from the event. Previous studies have estimated surprise based on the probability d...

Facial color varies depending on emotional state, and emotions are often described in relation to facial color. In this study, we investigated whether the recognition of facial expressions was affected by facial color and vice versa. In the facial expression task, expression morph continua were employed: fear-anger and sadness-happiness. The morphe...

Preverbal 10-month-old infants show sympathetic responses as their preference for others in distress (Kanakogi et al., PLoS ONE 2013). We aimed to investigate if the preference for others in distress changes in development, and is affected by cultural and community differences. In Experiment 1, fifty-two university students (2 females, 50 males) in...

Brain computer interface (BCI) is a system for communication between people and computers via brain activity. Steady-state visual evoked potentials (SSVEPs), a brain response observed in EEG, are evoked by flickering stimuli. SSVEP is one of the promising paradigms for BCI. Canonical correlation analysis (CCA) is widely used for EEG signal processi...

In this research, we develop a BRI based on Steady-State Visually Evoked Potentials (SSVEP). We apply this BRI to a tele-presence robot system. The user puts on BRI to provide information to the system, and the robot presents choices to the user only when the decision is necessary for selecting the destination or the person to talk with. The BRI ov...

In daily life, we can attend to multiple moving objects. For example, the drivers always pay attention to pedestrians, cars and so on while driving a car. Attention to multiple moving targets is an essential ability of visual system. Extracting information to which the driver pays attention may allow us to prevent the accidents caused by lack of at...

Using ultrasonic motors, we propose a compact and highly responsible eye robot that is moved by transmitting a operator eye movement to the robot's eye, to obtain the visual information of the environment surrounding the robot. In addition, we propose a graphical user interface (GUI) that makes the robot operation intuitive.

Faces are important for social interaction because much can be perceived from facial details, including a person's race, age, and mood. Recent studies have shown that both configural (e.g., face shape and inversion) and surface information (e.g., surface color and reflectance properties) are important for face perception. Therefore, the present stu...

Recent studies have suggested that both configural information, such as face shape, and surface information is important for face perception. In particular, facial color is sufficiently suggestive of emotional states, as in the phrases: "flushed with anger" and "pale with fear." However, few studies have examined the relationship between facial col...

In this paper, we propose an eye robot system with master slave control using operator-gaze tracking data, which can produce a high response level such as that of the human eyes. The operators can move a remote robot camera by only moving their eye (master) in front of an eye tracking apparatus and obtain visual information of the environment surro...

Facial color is important information for social communication as it provides important clues to recognize a person's emotion and health condition. Our previous EEG study suggested that N170 at the left occipito-temporal site is related to facial color processing (Nakajima et al., [2012]: Neuropsychologia 50:2499–2505). However, because of the low...

This research aims to develop a BMI for controlling a mobile robot in road-like environments. The robot makes a local map of the surrounding scene using a laser range finder and recognizes the intersection type, which is sent to the BMI. The BMI flashes LEDs corresponding to possible branches of the current intersection, and determines the operator...

Necker cube is one of the ambiguous figures that are physically static image but can be alternately perceived in two different perspectives. A great deal of debate exists regarding ambiguous figures that induce spontaneous switching between rival percepts. To investigate the time course of neural processes underlying such perceptual rivalry, we rec...

Insight is commonly described as sudden comprehension, sometimes called an "Aha! moment." In everyday life, we apply the process of insight to problems that are difficult to solve at first glance or that we perceive as ambiguous, however the brain dynamics underlying the disambiguation process remains elusive. Beta-band oscillatory brain activity h...

Repeated exposure to neutral stimuli enhances liking for those, which is called Mere exposure effect (MEE) (Zajonc, 1968). Its behavioral effects have been extensively investigated. However, the mechanism by which it is generated remains unclear. To elucidate the neural mechanism of the MEE, we recorded electroencephalograms while subjects indicate...

The affect misattribution procedure (AMP) was proposed as a technique to measure an implicit attitude to a prime image [1]. In the AMP, neutral symbols (e.g., a Chinese pictograph, called the target) are presented, following an emotional stimulus (known as the prime). Participants often misattribute the positive or negative affect of the priming im...

Faces play an important role in social interaction by conveying information and emotion. Of the various components of the face, color particularly provides important clues with regard to perception of age, sex, health status, and attractiveness. In event-related potential (ERP) studies, the N170 component has been identified as face-selective. To d...

In humans, face configuration, contour and color may affect face perception, which is important for social interactions. This study aimed to determine the effect of color information on face perception by measuring event-related potentials (ERPs) during the presentation of natural- and bluish-colored faces. Our results demonstrated that the amplitu...

This study aims to examine how the strength of memory colors affects the ERP, especially focusing on the P3 component. In Experiment 1, seven subjects (mean age : 22.5) were asked to adjust the color of objects until they appeared typical color, in order to measure individual typical colors of a grape, a banana, a man face, and a Coca Cola's logo....

This study examined the relationship between the 'naturalness' of a visual stimulus and the event-related potentials measured during an oddball task. The study focused on asymmetry of the P3 amplitude during an oddball task or P3 asymmetry. Participants performed two visual oddball tasks using a pair of stimuli (A and B): one in which A was the tar...

Face perception is important for our social interaction. When we perceive faces, not only face features such as its configuration and contour but also face color might affect our face perception. This study aimed to reveal the effect of the color information on face processing and an event-related potential (ERP) was measured while natural color fa...

In understanding the environment around us, we do not perceive our exact sensory input as is. Instead, we divide the world into meaningful groups or categories. This categorization function is fundamental to cognitive processes. Such categories are processed in brain areas such as the inferior temporal cortex (ITC) and prefrontal cortex (PFC). To c...

We developed a recurrent neural network model of rule-guided behavior to simulate neural activity in rule-guided tasks. Our model was constructed using neural system identification (Neurosci. 47 (4) (1992) 853) and a fully recurrent neural network model was optimized to perform a rule-guided delayed task. The response properties of the hidden units...

The ability to use abstract rules is very important in applying our experience to new situations. To examine the system governing such rule-guided behavior, we developed a recurrent neural network model of rule-guided behavior and simulated a physiological experiment involving a rule-guided delayed task (Wallis, Anderson, & Miller, 2001). Our model...

In order to investigate encoding of rules in the prefrontal (PF) cortex, we simulated the physiological results of Wallis et al. (2001). They explored its neural basis by recording from single neurons in the PF cortex of monkeys trained to use two rules. As a result, they found neurons selective for learned rules regardless of samples and cues. How...

Physiological studies have revealed that the prefrontal cortex (PF) plays an important role in working memory, which retains relevant information on line. Rao et al. (1997) found neurons contributing to both object and spatial working memory. However, their mechanisms are still unknown. In this study, we propose a neural networkmodel of working mem...