Sangin Park

SSVEP and ERP measurement of cognitive fatigue caused by stereoscopic 3D.

The purpose of this study was to identify steady-state visually evoked potential (SSVEP) and event-related potential (ERP) correlates of 3D cognitive fatigue. Twenty-one participants (11 females) were subjected to a cognitive test before and after being exposed to a stereoscopic 3D environment. They were categorized into two groups, fatigued and unfatigued, based on their response times and subjective data. The fatigued group exhibited significantly reduced P600 amplitudes and delayed P600 latencies in the post-viewing condition compared to those in the pre-viewing condition. Significant fatigue effects for the fatigued group were also observed at P(4) and O(2) sites during the 8.57 Hz attended task; attend/ignore ratios in this cortical hemisphere after 3D viewing were smaller than those before 3D viewing.

Does visual fatigue from 3D displays affect autonomic regulation and heart rhythm

Most investigations into the negative effects of viewing stereoscopic 3D content on human health have addressed 3D visual fatigue and visually induced motion sickness (VIMS). Very few, however, have looked into changes in autonomic balance and heart rhythm, which are homeostatic factors that ought to be taken into consideration when assessing the overall impact of 3D video viewing on human health. In this study, 30 participants were randomly assigned to two groups: one group watching a 2D video, (2D-group) and the other watching a 3D video (3D-group). The subjects in the 3D-group showed significantly increased heart rates (HR), indicating arousal, and an increased VLF/HF (Very Low Frequency/High Frequency) ratio (a measure of autonomic balance), compared to those in the 2D-group, indicating that autonomic balance was not stable in the 3D-group. Additionally, a more disordered heart rhythm pattern and increasing heart rate (as determined by the R-peak to R-peak (RR) interval) was observed among subjects in the 3D-group compared to subjects in the 2D-group, further indicating that 3D viewing induces lasting activation of the sympathetic nervous system and interrupts autonomic balance.

Autonomic nervous system responses can reveal visual fatigue induced by 3D displays.

Previous research has indicated that viewing 3D displays may induce greater visual fatigue than viewing 2D displays. Whether viewing 3D displays can evoke measureable emotional responses, however, is uncertain. In the present study, we examined autonomic nervous system responses in subjects viewing 2D or 3D displays. Autonomic responses were quantified in each subject by heart rate, galvanic skin response, and skin temperature. Viewers of both 2D and 3D displays showed strong positive correlations with heart rate, which indicated little differences between groups. In contrast, galvanic skin response and skin temperature showed weak positive correlations with average difference between viewing 2D and 3D. We suggest that galvanic skin response and skin temperature can be used to measure and compare autonomic nervous responses in subjects viewing 2D and 3D displays.

Evaluation of 3D cognitive fatigue using heart–brain synchronization

The purpose of this study was to identify an evaluation method for 3D cognitive fatigue based on a heart-brain synchronization phenomenon known as the heartbeat evoked potential (HEP). Thirty undergraduate students (15 females) watched a video in both 2D and 3D for an hour. Because visual fatigue is related to cognitive load, the HEP was used as an indicator of communication between the heart and the brain and therefore of cognitive function; responses were compared after 2D and 3D viewing. At the standard EEG sites F3 and F4, the alpha activity of the first and second HEP components was significantly increased after 3D video viewing relative to 2D. This increase likely indicates that sensory input from 3D video requires heavy computation by the brain, stimulating heart activity. The conclusion is that the first and second HEP components are significant parameters that can quantitatively evaluate 3D visual fatigue. Further work is needed to uncover the cause of 3D visual fatigue.

Interactive emotional lighting system using physiological signals

This paper proposes an emotionally interactive lighting system to support affective experiences while enjoying video content. The emotional lighting system is controlled by changes in an individual¿s emotional state. The newly designed system consists of an emotion recognition system that uses three different physiological signals (photoplethysmography, skin temperature, and galvanic skin response), an emotion lighting control system, and an emotion ambient lighting system. The physiological responses of nineteen subjects are evaluated in terms of emotional arousal and relaxation states with two different colors of light. The physiological signals are analyzed in both the time and frequency domain, and test results show that the peak-to-peak interval value and ratio of high to very-low frequencies of the photoplethysmography signals decreases significantly following a red light stimulus when arousing video content is played, whereas the same factors exhibit a significant increase after a blue light stimulus while relaxing video content is watched. These results show that red and blue light is an effective intensifier of emotional arousal and relaxation experiences during displays of arousing and relaxing video content, respectively.

Non-contact measurement of heart response reflected in human eye

This study aims to develop a non-contact measurement technique for cardiac response that uses an infrared image of the patients pupil. The pupil contraction rhythm is related to the autonomic balance and major organs (such as the heart) via a neural pathway. In this study, the response of the heart was determined by analyzing the pupillary rhythm based on the harmonic frequencies between them. Seventy undergraduate volunteers of both genders, (35 females and 35 males), with ages ranging between 20 and 30years (mean: 24.52±0.64years) were asked to conduct a simple conversation, perform slight movements, and experience sound stimuli to evoke arousal, relaxation, happiness, sadness, or a neutral mood in this experiment. Electrocardiograms and pupil images were measured and analyzed, and the harmonic frequencies were identified to determine the relational response. The cardiac time (heart rate (HR), beats per minute (BPM), the standard deviation of the normal-to-normal (NN) intervals (SDNN), the mean squared differences in the successive N-N intervals (rMSSD), and the percentage difference between adjacent normal interbeat (R-R) intervals>50 (pNN50)) and frequency (very low frequency (VLF), low frequency (LF), high frequency (HF), VLF/HF, and LF/HF) parameters were also observed with regard to the effects of the movement, conversation, and physiological state. The cardiac response was stable, showing less significance than the effects of the three conditions. Therefore, multi-cardiac measurements were successfully obtained from a simple, low-cost, non-invasive, and non-contact data acquisition method in this study.

A New Social Emotion Estimating Method by Measuring Micro-movement of Human Bust

In this study, we propose a new micro-movement analyzing method of the human bust to estimate social emotions with human relations. In previous research for quantitatively measuring human intention and emotion, physiological sensors such as ECG, PPG, GSR, SKT, and EEG have been analyzed. However, these methods cannot avoid the measurement burden caused by sensor attachment. This may result in negative emotions that skew the true evaluation. To solve these problems, we focus on micro-body movement responding emotions. Micro-body movements are determined by analyzing successive image frames captured from a conventional webcam. The amount of the bust micro-movement is then obtained by subtracting two adjacent image frames. Based on the interval between the two image frames, the amounts of micro-movement per several frequency bands can be acquired. Because the calculated successive values of bust micro-movement are in the form of 1D temporal signal, it can be general method for all conventional temporal signal processing. The results showed less micro-movement in the case of an intimate relation group compared with the case of a non-intimate one.

Vision Based Body Dither Measurement for Estimating Human Emotion Parameters

In this paper, we propose a new body dither analyzing method in order to estimating various kinds of intention and emotion of human. In previous researches for quantitatively measuring human intention and emotion, many kinds of physiological sensors such as ECG, PPG, GSR, SKT, and EEG have been adopted. However, these sensor based methods may supply inconvenience caused by sensor attachment to user. Also, therefrom caused negative emotion can be a noise factor in terms of measuring particular emotion. To solve these problems, we focus on facial dither by analyzing successive image frames captured from conventional webcam. For that, face region is firstly detected from the captured upper body image. Then, the amount of facial movement is calculated by subtracting adjacency two image frames. Since the calculated successive values of facial movement has the form of 1D temporal signal, all of conventional temporal signal processing methods can be used to analysis that. Results of feasibility test by inducing positive and negative emotions showed that more facial movement when inducing positive emotion was occurred compared with the case of negative emotion.

Infrared Camera-Based Non-contact Measurement of Brain Activity From Pupillary Rhythms

Pupillary responses are associated with affective processing, cognitive function, perception, memory, attention, and other brain activities involving neural pathways. The present study aimed to develop a noncontact system to measure brain activity based on pupillary rhythms using an infra-red web camera. Electroencephalogram (EEG) signals and pupil imaging of 70 undergraduate volunteers (35 female, 35 male) were measured in response to sound stimuli designed to evoke arousal, relaxation, happiness, sadness, or neutral responses. This study successfully developed a real-time system that could detect an EEG spectral index (relative power: low beta in FP1; mid beta in FP1; SMR in FP1; beta in F3; high beta in F8; gamma P4; mu in C4) from pupillary rhythms using the synchronization phenomenon in harmonic frequency (1/100 f) between the pupil and brain oscillations. This method was effective in measuring and evaluating brain activity using a simple, low-cost, noncontact system, and may be an alternative to previous methods used to evaluate brain activity.

Effects of mental workload on involuntary attention: A somatosensory ERP study

Abstract Previous psychophysiological assessments of mental workload have relied on the addition of visual or auditory stimuli. This study investigated the tactile ERP and EEG spectral power correlates of mental workload by relating limited‐capacity involuntary attention allocation to changes in late positive potential (LPP) amplitude, alpha, and theta powers. We examined whether mental workload (high‐level cognitive control) can be evaluated using somatosensory stimuli. Sixteen participants all performed three tasks of varying difficulty. Two dual n‐back tasks (n = 1 and 2) were used to investigate the degree to which mental workload affected the LPP amplitudes and EEG spectral powers evoked by ignoring salient tactile stimuli. In control trials, tactile vibrations were applied at random without dual n‐back tasks. Subjective mental workload of each task was rated using the NASA Task Load Index. LPP amplitudes at Pz were significantly smaller in the dual‐2‐back trials compared to control and dual‐1‐back trials. Significantly increased theta power at Fz and reduced alpha power at Pz were found in the dual‐2‐back condition compared to control and dual‐1‐back condition. There was no significant difference between control and dual‐1‐back trials. The same pattern was found for subjective ratings of cognitive workload. These results indicate that the dual‐2‐back task imposed a significantly greater mental workload, causing impaired cognitive‐control functions. Our findings support the notion that selective attention mechanisms necessary for effectively allocating and modulating attentional resources are temporarily impaired during the mentally overloaded state. HighlightsLate positive potentials (LPP) have been suggested to indicate mental workload.Mental workload affected LPP amplitudes evoked by salient ignored tactile stimuli.LPP amplitudes were reduced under more cognitively demanding conditions.Mental workload resulted in increase in theta power at Fz.Reduced alpha activity at Pz was associated with increasing mental workload.