Byung-Chan Min

Effects of three levels of arousal on 3-back working memory task performance

This study investigated how three levels of arousal affected performance of a 3-back working memory task. Ten female and ten male university students participated in this experiment. With pictures selected from a group test, three levels of arousal were induced––i.e., tense, neutral, and relaxed emotions. Each subject was run through the procedure three times, once for each arousal level. The procedure consisted of six phases for each arousal condition: (1) Rest 1 (2 min), (2) Picture 1 (presenting emotion arousing photos for 2 min), (3) 3-back working memory task 1 (2 min), (4) Picture 2 (presenting emotion-arousing photos for 2 min), (5) 3-back working memory task 2 (2 min), and (6) Rest 2 (2 min). The skin conductance level of electrodermal activity was also measured during all phases of the experiment. The accuracy rate of 3-back working memory task performance was the highest at a neutral emotional state, followed by relaxed and then tense emotional states. There were no significant differences in reaction time.

The effects of disruption in attention on driving performance patterns: analysis of jerk-cost function and vehicle control data.

This study analyzes the effects of attention disruption factors, such as sending text messages (STM) and performing searching navigation (SN) on driving performance patterns while actively driving, centering on motion signals. To this end, it analyzes not only data on control of the vehicle including the Anterior-Posterior Coefficient of Variation (APCV), Medial-Lateral Coefficient of Variation (MLCV), and Deviation of Vehicle Speed but also motion data such as the Jerk-Cost function (JC). A total of 55 drivers including 28 males (age: 24.1 ± 1.5, driving experience: 1.8 years ± 1.7 years) and 27 females (age: 23.8 ± 2.6, driving experience: 1.5 ± 1.0) participated in this study. All subjects were instructed to drive at a constant speed (90 km/h) for 2 min while keeping a distance of 30 m from the front car also running at a speed of 90 km/h. They were requested to drive for the first 1 min and then drive only (Driving Only) or conduct tasks while driving for the subsequent 1 min (Driving + STM or Driving + SN). The information on APCV, MLCV, and deviation of speed were delivered by a driving simulator. Furthermore, the motion signal was measured using 4 high-speed infrared cameras and based on the measurement results, JCs in a total of 6 parts including left shoulder (L.shoulder), left elbow (L.elbow), left hand (L.hand), right knee (R.knee), right ankle (R.ankle), and right toe (R.toe) were calculated. Differences among the results of 3 conditions of experiment, Driving Only, Driving + STM, and Driving + SN, were compared and analyzed in terms of APCV, MLCV, Deviation of Vehicle Speed, and JC. APCV and Deviation of Vehicle Speed increased in Driving + SN, rather than in Driving Only. MLCV increased in Driving + STM and Driving + SN, rather than in Driving Only. In the case of most JCs except that of L.hand, the values increased in Driving + SN, compared to Driving Only. This study indicated that JC could be a reliable parameter for the evaluation of driving performance patterns. In addition, it was discovered that additional tasks under driving, such as STM and SN, impaired smoothness or proficiency in driving motion, thereby increasing anterior-posterior and medio-lateral variability and deviation of speed.

Activation of the limbic system under 30% oxygen during a visuospatial task: An fMRI study

The purpose of this study was to observe activation of the limbic system during the performance of visuospatial tasks under 21% O(2) or 30% O(2). Eight right-handed male college students were selected as subjects for this study. A visuospatial task was presented while brain images were scanned by a 3T fMRI system. The experiment consisted of the following two runs: a visuospatial task under normal air (21% O(2)) and a visuospatial task under hyperoxia (30% O(2)). The accuracy rate on the visuospatial task was enhanced during 30% O(2) compared to 21% O(2). The neural activation areas of the limbic system were similar in the cingulate gyrus, thalamus, limbic lobe and parahippocampal gyrus. Increased neural activation was observed in the cingulate gyrus and thalamus under 30% O(2) compared to 21% O(2). Under 30% O(2), the improvement in visuospatial task performance was related to an increase in neural activation of subcortical structures, such as the thalamus and cingulate gyrus, as well as the cerebral cortex.

Difference of driving performance according to turn types at the intersection and age

This study examined the difference of driving performance according to turn types (left /right turn), suggested by Bao and Boyle (2009), and age(old and young adults). To do that, the turn types at the intersection were divided into 12 scenarios of left and right turn, respectively and by making approach velocity at the intersection, the passing time at the intersection, the speed and steering variation while passing the intersection as the measures of driving performance were measured by using two age groups, young and old adults. As a result, young drivers approached and passed the intersection faster than older drivers. It suggests that old drivers have a low level of driving confidence, which can be interpreted as a result of a kind of compensatory behavior when considering their physical degradation. Also, compared with the right turn intersection, there was a big speed variation while turning at the left turn intersection. It is reflecting the driving behavior which appears because a driver recognizes that there is more information to be confirmed constantly for safety driving while turning left, compared with right turn. However, it suggests that a driver might have accidents while turning right at the intersection when the objects besides vehicles appear because of this driving behavior, as suggested by Summala, et al.(1996).

Cerebral Lateralization Index Based on Intensity of Bold Signal of FMRI

This study proposes a new cerebral lateralization index (LI) on the basis of neural activation intensity. Eight right-handed male college students (mean age 23.5 years) and 10 right-handed male college students (the mean age 25.1 years) participated in this study of visuospatial and verbal tasks, respectively. Functional brain images were taken from 3T MRI using the single-shot EPI method. A cerebral LI based on neural activation area (i.e., number of activated voxels) and another based on neural activation intensity (i.e., intensity of BOLD (blood oxygen level dependent)) were calculated for both cognition tasks. The result of calculating a cerebral LI based on neural activation area suggested that the right hemisphere is dominant during visuospatial tasks and the left hemisphere is dominant during verbal tasks. When a cerebral LI was computed on the basis of the neural activation intensity, it was shown that the area of cerebral lateralization closely related to visuospatial tasks is the superior parietal lobe, and the area of cerebral lateralization closely related to verbal tasks is the inferior and middle frontal lobe. Since the proposed method can determine the dominance of the cerebrum by each area, it can be helpful to determine cerebral lateralization accurately and easily.

Driving Performance Changes of Middle-Aged Experienced Taxi Drivers Due to Distraction Tasks during Unexpected Situations

This study investigated the effects of distraction tasks—such as sending a text message with a cellphone and searching navigation with car navigation system—on the driving performance of 29 highly experienced taxi drivers in their 50 s. All participants were instructed to drive using a driving simulator for 2 min. while maintaining a constant distance from the vehicle in front and a constant speed. Participants drove without any distractions for the first minute. For an additional minute, they performed Driving Only or performed a task while driving (Driving + Sending Text Message or Driving + Searching Navigation). An unexpected situation, in which the participant had to stop abruptly due to a sudden stop of the preceding vehicle, occurred during this period. Driving performance during the unexpected situation was evaluated by car control variables, medial-lateral coefficient of variation and brake time, and by motion variables such as the jerk-cost function. Compared to Driving Only, jerk-cost function, medial-lateral coefficient of variation, and brake time increased during Driving + Sending Text Message or Driving + Searching Navigation.

A Study on the Cerebral Sizes of Koreans in Their 20S and 40S

The purpose of this study was to measure the cerebral sizes of Korean adults in their third (20s) and fifth decades (40s) of life using Talairach-Nowinski reference points to determine the effect of sex and age on cerebral size and asymmetry. Magnetic resonance images of the brain of 94 adults between 20 and 29 years of age (43 males and 51 females) and 99 adults between 40 and 49 years of age (38 males and 61 females) were measured. The distance between reference points and cerebral size of males was greater than those of females. Cerebral width and the size of the left cerebrum of those in their 40s decreased more than those in their 20s. The effect of age on left cerebral atrophy of males was greater than that of females. Left cerebral size was greater than right cerebral size. There was no difference in cerebral asymmetry between the genders. Cerebral asymmetry of those in their 40s was smaller than of those in their 20s and the decrease of cerebral asymmetry of males due to age was greater than that of females. A positive relationship existed between cerebral height, and body height and weight for males in their 20s.

A Study on Changes in Human Sensibility Evoked by Imagination

In this study, emotion changes were induced by four imaginations- pleasantness, unpleasantness, arousal, relaxation and it was examined using subjective evaluation and analysis of the physiological signals of the central and autonomic nerve systems whether the intended emotions were appropriately achieved, and whether these emotion changes could be distinguished from the analysis of physiological signals. Each of the four imaginations was implemented on 32 subjects for 30 seconds, while that Electroencephalogram (EEG), Eelectrocardiogram (RSP) were measured, and a subjective evaluation was implemented following the completion of the measurement. The analysis of the subjective evaluation revealed that the subjects underwent the four clearly differentiated imaginations, and the pleasantness level was classified into four imagination stages, pleasantness>relaxation>arousal

Study on driving performance of aged drivers at the intersections compared with young drivers

In the recent aged society, the framework for assisting safe driving should be prepared with understanding the elderly drivers driving performance and their psychological features. The purpose of this study is aimed to obtain the fundamental data of aged driver for their effective assist-system. First, using driving simulator, aged people were observed their driving behaviors in various conditions at intersections compared with young drivers. These behaviors were measured in the condition of right and left turns and crossing. As the results, in particular, significantly slower approaches were observed on every occasion, and the unstable driving behaviors were examined. Next, on the field tests of real running in proving ground, the aged drivers were apt to run rapidly in the case of approaching the crossing compared with young drivers. These driving performances should be interfered with the traffic flow and exposed to the risk of accidents.

The differences of eye movement according to turn conditions in driving situation: Comparison of older and younger drivers

This research examined differences of eye movement in left or right turn conditions at each of intersection type between older and younger drivers. To examine these differences, we measured visual scanning time by eye-marker. The results showed that on the type T1 which has the front, the left, or the right roads, older drivers tend to keep eyes on the front for a short time than younger drivers in turning right. On the type T2 which has the left and the right roads, older drivers watched the left for a short time in turning left than younger drivers, while watching the right for a long time in turning right. On the type Cross which has the front, the left, and the right road, older drivers kept eye on the front for a short time in turning right than younger drivers. The results indicate that older drivers could perform more risky driving behavior in turning right at the intersection which has the front road than younger drivers. It also suggested that older drivers could perform more risky driving behavior in turning left at the intersection which has the left and right roads than older drivers, but they could perceive accurately the unexpected driving in right turning situation.