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Lambda response is obtained by averaging EEGs time-locked to the offset of saccadic eye movements (saccades) with a peak latency of about 100 ms from the offset of saccades. Lambda response is thought to be evoked by the inflow of visual information after the termination of the saccade. The purpose of the present study is to evaluate the effect of stimulus contrast on lambda response. Eighteen normal adults participated in the experiment. The stimuli were vertical black-and-white sinusoidal gratings of three spatial frequencies (0.5, 1 and 3 cycles/degree, cpd). Stimulus contrast ranged from 0% to 96%. The subject made horizontal saccades between two fixation points at a constant pace. At spatial frequencies of 0.5 and 1 cpd, the peak latency of lambda response decreased as the stimulus contrast increased. At spatial frequency of 3 cpd, the peak latency did not vary with the stimulus contrast. The peak amplitude of lambda response did not vary with the stimulus contrast at spatial frequencies of 0.5 and 1 cpd, but it did at spatial frequency of 3 cpd. These results indicate that the effect of stimulus contrast on lambda response changes according to the stimulus spatial frequency. They also suggest that lambda response may be a useful index of visual information processing with eye movements.

When we measure the visual event-related potential (ERP), a subject has to fix eyes to a point on the display in an experimental situation or in a diagnosis on the visual function. Therefore, it is very hard to apply the event-related potential (ERP) to assessment of sensation and attention at clinical fields or at industrial settings. We developed a system to analyze the brain potential associated with offset of saccadic eye movements. The potential is called eye fixation-related potential (EFRP). EFRP is identical with the so-called visual ERP. We can measure the topographical change of EFRP in real time. The first system with a UNIX (Version 1) was very fast, but very expensive. However, the new system (Version 2) is more economical, because it can be used in a notebook computer with Windows XP. EEG and EOG data can be sampled in real time, although the data are analyzed offline. The new system will be useful to study cognitive factors under eye movement conditions.

The purpose of this study was to examine the effects of biological sex and masculinity/femininity on physiological (blink and heart rates), emotional (anxiety and mood), and behavioral responses (behavioral ratings of communication skills) during communication situations. Participants were 46 students in a Japanese university. They were categorized into 3 gender types—androgynous, stereotypical, and cross-gender on the Masculinity–Humanity–Femininity Scale (Ito, 1978) and the Social Skills Inventory (Riggio, 1986). The communication situations consisted of 2 experimental tasks (question-asking and self-introduction in front of a video camera). These two tasks were conducted in both Japanese and English. The results suggested that the cross-gender-type participants (feminine men and masculine women) showed increased blink and heart rates. For the behavioral ratings, the cross-gender type and the androgynous gender type were judged to have better communication skills than the stereotypical gender type. There was no significant difference in emotional responses among groups. The interaction of biological sex and masculinity/femininity may be associated with interpersonal adjustment and its stress responses.

Blinking behavior during conversation may be different between conditions in listening and responding to questions because sifting attention from external to internal is possibly associated. The purpose of this study was to compare blinking behavior, duration, heart rates, and mental states during the tasks of listening to and responding to questions in Japanese and English. Participants were 67 (35 men and 32 women) undergraduate students. Blink rate while responding to questions in English did not differ from that while responding to questions in Japanese, but blink rate while listening to questions in English was significantly reduced compared to that while listening to Japanese. While anxiety and uneasiness were increased by the English conversation, blink rate and heart rate were decreased. Blinking behavior may be related to thinking and attention.

The sequence of neural activation during a visual search task was investigated using magnetoencephalography and the source locations for the activations were analyzed using a single-dipole algorithm. Five components (M1–5) were detected at mean latencies of 110, 146, 196, 250 and 333 ms in both of two different stimulus conditions; a target popped out in one stimulus condition (pop-out), while it did not in the other condition (non-pop-out). Statistical analysis showed that the M3 amplitude was larger and the M5 latency was shorter in the pop-out condition than in the non-pop-out condition, while there was no difference in the other components between the conditions. Neural sources were localized in the calcarine sulcus (M1) and the posterior fusiform gyrus (M2) of the hemisphere contralateral to the stimuli, the intraparietal sulcus and the posterior superior temporal sulcus (M3) in either of the hemispheres, and the calcarine sulcus (M4) of the same hemisphere in which the early processing (M1 and M2) occurred. The criteria for source localization were not satisfied for M5. The results suggest that the processing for pop-out and non-pop-out stimuli share a common mechanism; after early feature processing in the occipital cortex (M1 and M2), visual information is processed in the parietal and temporal regions (M3) and then some of this information is fed back to the occipital cortex (M4).

Sixteen subjects sat in a rotating optokinetic drum and were instructed to stare moving vertical stripes inside of the optokinetic drum. Speeds of the stripes were five visual angles (12, 24, 36, 48, 60 deg/s). EEGs and EOGs were measured. EEG epochs were averaged at onset of slow phases (pursuits) of the optokinetic nystagmus (OKN). The positive component of latency of about 100 ms appeared predominantly at the occipital region of 15 subjects in all conditions. The positive component might be the same as the lambda response that appears in EFRP to a stationary object.

When electroencephalograms (EEGs) are averaged at eye fixation pauses (at the end of saccades), the specific brain potentials related to the visual information processing can be obtained. This eye-fixation-related potential (EFRP) is a type of event-related potential. In this paper, the authors introduced two systems developed at their laboratory. The first measured the distribution of EFRPs on the scalp with DC amplifiers in order to nullify eye movement artifacts. Three-dimensional EFRP topographies were obtained. The most prominent component (lambda response) of the waveform appeared at occipital sites. The second system was designed to examine the variation in EFRPs over time, using a sliding average method. The dynamic variation in EFRPs could be observed as an animation. The sequence of variations in amplitude was continuously displayed on a screen. This indicated the process of decrease and recovery of the lambda response generated by changes between periods of brightness and darkness.

The variations of eye fixation related potentials (EFRPs) were examined in two tasks under three lighting conditions for assessment of lighting environments. Sixteen subjects participated in two tasks; a difficult and an easy reading task under three lighting conditions: Spot light (S), General light (G) and Mixed light (M). EEG (Oz) and EOG were recorded. EEG epochs time-locked to onset of eye fixations were collected at random and averaged separately in two arrays to obtain a pair of EFRPs. Two wave forms under the S were similar, although those under the G showed the disparity, the largest disparity being in the easy task under the G. Under the S, wave forms of EFRPs were stable in the difficult task. The amplitude changed with the task load. The results suggested that EFRPs might be an index of the work load under lighting conditions.

Phonological priming effects on auditory event-related brain potentials were compared across different numbers of syllables shared between target words and preceding prime words or pseudowords. All items of words and pseudowords consisted of 3 syllables, and the subject's task was to make a judgment whether the item belonged to a designated category. A large negative wave (N400), commencing at about 250 ms poststimulus and lasting for about 700 ms, was observed irrespective of primes and targets. When targets were preceded by word-primes that shared the first one or two syllables, the onset of N400 at the frontal site was earlier and the initial negative-going phase was steeper than in other conditions. In contrast, the magnitude of N400 to targets was reduced, when the primes were pseudowords that shared the first two syllables. These two types of early and later phonological priming effects were interpreted to reflect facilitations during spoken word recognition at the pre-lexical (phonological) and post-lexical (semantic or contextual integration) levels, respectively.

The present study examined how the level of trait anxiety, which is a personality characteristic, influences state anxiety and penalty shoot-out performance under pressure by instruction. The high and low trait anxiety groups were selected by using Spielberger's Trait Anxiety Scale, with trait anxiety scores, and control and pressure conditions manipulated by instructions. The participants were two groups of eight university male soccer players. They individually performed 20 shots from the penalty shoot-out point, aiming at the top right and top left corner areas in the soccer goal. Each condition had 10 trials in a within-subject design. The dependent measures comprised the number of successful goals and the state anxiety scores under each instructional condition. The result showed a significant main effect of instruction. State anxiety scores increased more and the number of successful goals decreased more in high trait anxiety groups than in low trait anxiety groups under pressure instructional condition. These findings suggest that players with higher trait anxiety scores tend to experience increased state anxiety under a pressure-laden condition, and higher state anxiety interferes with goal performance.

This study examined how olfactory perception is influenced by visual cues (ie, color). In Experiment 1, fourteen participants judged perceived mixture ratio of the binary odor (citrus fruit and aromatic tree) by using ratio estimation method under one of two color conditions (yellow and purple). Each color was congruent with one of odor components. Perceived mixture ratios for the odorant congruent with the presented color were higher than those for the odorant incongruent with the color. Experiment 2 was conducted to confirm the possible response-bias effect on their judgment with the same participants. Conditions were same as Experiment 1 except that only one odorant was presented at a time. The effect of color was not observed, indicating that their judgments were not contaminated with response-bias. Thus, these results indicate that the odorant congruent with the presented color was perceived dominantly in a mixed odor, but this could be observed only when the odor stimuli contained that odorant. This study suggests that particular odorant congruent with a color cue is perceived selectively from a mixture odor. This finding may reflect the olfactory selective attention in mixed odor, attracted by the color as a cue to the specific odorant.

Human observers see a single mixed color (yellow) when different colors (red and green) rapidly alternate. Accumulating evidence suggests that the critical temporal frequency beyond which chromatic fusion occurs does not simply reflect the temporal limit of peripheral encoding. However, it remains poorly understood how the central processing controls the fusion frequency. Here we show that the fusion frequency can be elevated by extra-retinal signals during smooth pursuit. This eye movement can keep the image of a moving target in the fovea, but it also introduces a backward retinal sweep of the stationary background pattern. We found that the fusion frequency was higher when retinal color changes were generated by pursuit-induced background motions than when the same retinal color changes were generated by object motions during eye fixation. This temporal improvement cannot be ascribed to a general increase in contrast gain of specific neural mechanisms during pursuit, since the improvement was not observed with a pattern flickering without changing position on the retina or with a pattern moving in the direction opposite to the background motion during pursuit. Our findings indicate that chromatic fusion is controlled by a cortical mechanism that suppresses motion blur. A plausible mechanism is that eye-movement signals change spatiotemporal trajectories along which color signals are integrated so as to reduce chromatic integration at the same locations (i.e., along stationary trajectories) on the retina that normally causes retinal blur during fixation.

The purpose of this study was to examine whether a physical stimulus that deviates from a semantic context can elicit the N400 component of event-related brain potentials (ERPs). ERPs were recorded while 12 students judged the veracity of a simple statement (e.g., red/is not/blue) presented with the order of subject (S), object (O), and verb (V), which is normal in Japanese grammar. In one condition, S was a color patch and O was a word representing the color, while in the other condition, S was a color name and O was patch. In both conditions, a late additional negative potential was elicited by the O stimulus when it was mismatched with S. In addition, the negativities elicited by the incongruous color patch and word had the same morphology and scalp distribution. The results indicate that not only a word but a physical stimulus which deviates from a semantic context can elicit the N400 component.

We used psychophysiological technology to examine the effect of an oral supplement, a combination of lutein, zeaxanthin and blackcurrant extract (LUT), on visual fatigue, within the context of a randomized, double-blind, placebo-controlled cross-over trial. The LUT supplement and placebo samples were randomly assigned to thirteen participants, who took the samples for two LUT (and vice versa) for another 2 week. Each participant completed visual proof reading tasks for 2h during each of four testing sessions. Saccade tests were administered before and after the proof reading task, during which the participants moved their eyes back and forth between two targets positioned in the center of two checkerboards. We recorded EEG, EOG, heart rate, and facial muscle potential/performance during the saccade tests. Blood pressure was measured and subjective fatigue and stress scores were collected before and after the proof reading task. We averaged EEG starting at saccade offset in order to analyze eye fixation related potentials (EFRP). Our results suggested that the proof reading task induced visual fatigue. An analysis of EFRP and other psychophysiological data revealed significant differences between the LUT and placebo conditions. These results suggest that supplementation with LUT could help to reduce symptoms of visual fatigue.

The eye fixation related brain potentials (EFRP) associated with the occurrence of fixation pause can be obtained by averaging EEGs at offset of saccades. EFRP is a kind of event-related brain potential (ERP) measurable at the eye movement situation. In this experiment, EFRP were examined concurrently along with performance and subjective measures to compare the effects of tracking difficulty during a dual-task. Twelve participants were assigned four different types of a tracking task for each 5 min. The difficulty of tracking task is manipulated by the easiness to track a target with a trackball and the easiness to give a correct response to the numerical problem. The workload of the each tracking condition is different in the task quality (the difficulty of perceptual motor level and/or cognitive level). As a result, the most prominent positive component with latency of about 100 ms in EFRP was observed under all tracking conditions. The amplitude of the condition with the highest workload was smaller than that of the condition with the lowest workload, while the effects of the task quality and the correspondency with the subjective difficulty in incremental step were not recognized in this experiment. The results suggested that EFRP was an useful index of the excessive mental workload.

The unique event related brain potential (ERP) called the eye fixation related potential (EFRP) is obtained with averaging EEGs at terminations of saccadic eye movements. Firstly, authors reviewed some studies on EFRP in games and in ergonomics and, secondly introduced a new system for assessment of visual entertainments by using EFRP. The distinctive feature of the system is that we can measure the ERP under the conditions where a subject moves eyes. This system can analyze EEG data from many sites on the head and can display in real time the topographical maps related to the brain activities. EFRP is classified into several components at latent periods. We developed a new system to display topographical maps at three latent regions in order to analyze in more detail psychological and neural activities in the brain. This system will be useful for assessment of the visual entertainment.

The purpose of this study was to compare the lambda response of eye-fixation-related potentials (EFRPs) with the P100 component of pattern-reversal visual-evoked potentials. EFRPs were obtained by averaging EEGs time-locked to the offset of the saccade. The dipole of the lambda response and that of the P100 component were estimated by the dipole-tracing method (Musha & Homma, 1990). The locations of their dipoles at the occipital sites were very close to each other when the difference waveform, which was calculated by subtracting the EFRP to the patternless stimulus from the EFRP to the patterned stimulus, was used for the lambda response. This finding implies that the lambda response and P100 have a common neural generator in the visual cortex. However, the peak latency of the lambda response was shorter than that of P100. The saccades in the EFRP trial were considered to be the cause of the difference.

In this study, participants were required to identify hierarchically structured patterns that appeared at either global or local level. Paquet and Merikle (1984 Canadian Journal of Psychology381 45–53) showed that global interference is affected by exposure duration in the processing of a hierarchical structure. They showed that only global-to-local interference occurred at short exposure durations. In contrast, global-to-local as well as local-to-global interference was observed at long exposure durations. They suggested that the effect of exposure duration with global interference depends on the high-spatial-frequency versus low-spatial-frequency channel. In the present study, exposure duration (short or long) was varied randomly from trial to trial (experiment 1), or held constant (experiment 2). In experiment 1, global-to-local interference occurred at both short and long exposure durations, even though the same physical properties existed as in experiment 2. In experiment 2, both global-to-local and local-to-global interference occurred at only long exposure durations, in line with the results reported by Paquet and Merikle. This suggests that the effect of exposure duration on global interference is explained not only by spatial-frequency channels, but also by attentional shift.

The eye fixation related potential (EFRP) associated with the occurrence of fixation pauses can be obtained by averaging EEGs at termination of saccades. EFRP is a kind of ERP measurable at the eye movement situation. Variations of EFRP were examined during a proof reading task for a long time. Two paragraphs of sentences were presented on the left and the right sides of a CRT. The paragraph on one side had some irrelevant words. Ten subjects were asked to detect the irrelevant words. The task started at 09.20 h and finished at 16.00 h and consisted of five blocks. The duration of each block was 1-h task and 10-min rest including a lunch (70 min). EEG and EOG were recorded during the task. EEGs were averaged at termination of saccades to obtain EFRP. EFRP showed little changes during the morning blocks. However, the mean amplitude between 100 and 200 ms of the positive component in the last two blocks decreased significantly compared with other blocks. The error rate, the performance and the score of fatigue increased at the end of the task. EFRP would reflect decline of mental concentration (i.e. carelessness) caused by visual fatigue.

Publisher Summary This chapter discusses the measurement of work load using brain potentials during video display terminal (VDT) tasks. For this purpose the variation of eye fixation-related potential (EFRP) is examined in which the subject is instructed to draw a same pattern at the fight side on the CRT as the stimulus figure presented at the left side without using copy command. However, no systematic variation or A B decrement in EFRP among blocks is found in the result. The pattern of the variation in amplitude seemed to relate to the arousal level. The test of the subjective symptoms on fatigue indicated that the subject felt fatigued by the tasks. The values were measured after the task, not during the task. In this study, the relationship between EFRP and fatigue of the subjects is not found. However, if the task continued longer period, EFRP might change more clearly. This research indicated that EFRP would be applicable as an index of the work load in the VDT task.

This study employed facial electromyography (EMG) as an index of subtle changes of facial expression due to changes in feelings assumed to be caused by odors. Facial EMG has been confirmed to discriminate positive feelings from negative ones, even when facial expressions are too faint to be observed. Most previous facial EMG studies [1,2] have used imagery strategy to create an emotional context. However, in this study, we measured EMG using olfactory stimuli.

The purpose of this study was to examine the effects on event-related brain potentials (ERPs) of occasionally presented deviants in a sequence of tones. The sequence consisted of a series of frequent standard C5 tones from the diatonic musical scale, in which three deviants (F#5, C6, and F#6) and a target (C4) were occasionally embedded. Twenty subjects were asked to detect the target. The deviants elicited frontal N2. The amplitude of the N2 was smaller for C6 than for the other two deviants, whereas peak latencies increased as a function of the frequency distance between the deviant and the standard. The smaller N2 to C6 than that to the other deviants was considered to reflect closer subjective distance due to the octave relationship between C6 and the standard C5.

The mismatch negativity (MMN), well established in auditory modality, reflects the automatic processing. In somatosensory modality, however, no MMN like component has been reported, in contrast to numerous studies concerning auditory MMN. In the present study, we investigated the response corresponding to MMN by using the deviant stimuli in a homogenous somatosensory stimuli sequence, while the subjects were reading a novel. In the first block, electric pulses were given repetitively to one finger as standard stimuli (90%) and occasionally to another finger as deviant stimuli (10%). In the second block, the stimulating site was exchanged. Each block was performed randomly and separately. In both blocks with ISI of 500 ms, the deviant stimuli elicited a positive deflection dominant at Cz, ranging from 100 to 200 ms in latency, suggesting that this positive deflection is related to the physical changes of the evoking stimulus. In addition the latency is comparable to one of the auditory MMN. Furthermore, we employed also the longer ISI (1000 ms) to confirm whether or not the present positivity is equivalent to MMN. As a result, the amplitude of this positivity was drastically decreased in the 1000 ms-lSI condition, suggesting that this somatosensory positivity may be related to the sensory memory like the auditory MMN.

Summary.-5 subjects were assigned two tasks during which they were simultaneously presented brightness-changes of the spot light on the CRT and the speech in a foreign language. They were asked to count the number of the changes in the visual task and listen to che speech to discern the content in the auditory task. A pair of averaged visual evoked potentials (VEP) to the brightness-changes were obtained for each task to calculate a subset correlation as an index of the variance of VEP. The mean correlation coefficient of VEP across the subjects was significantly higher during the visual task than that in the auditory task. This means that VEP mas more stable during the visual task. The result suggests that the subset correlation measure might be available to evaluate visual information-processing load. Enhanced amplitudes of the visual evoked potential (VEP) with higher information-procssing load have been reported in some papers (Donchin & Cohen, 1967; Harter & Salmon, 1972; Van Voorhis & Hillyard, 1977). Since the amplitude and the wave form of VEP are also varied with such factors as the stimulus pattern and the manner of stimulus presentation, it is considerably hard to identify the components of VEP collected among different conditions. Sabat (1978) mentioned that the wave form of the evoked potentials was more variable when attention to the stimulus was distracted. Callaway ( 1975 ) , who reviewed some methods evaluating the variability of the evoked potential, discussed that the subset correlation, which is similar to the split-half reliability coefficient, provides an index of similarity (or its inverse, variability) between AEPs collected under varying conditions. In the present experiment, we examined the possibility that the subset correlation measure would be applicable to evaluation for information-processing load.

The purpose of this study was to examine the nature of N2 component in event-related brain potentials (ERPs) which was associated with the deviation from the internal model of the semantic environment. Of the visually presented stimuli 60% were nouns belonging to the same semantic category (C), 20% belonged to other categories (NC), and the other 20% were nonwords (NW). 10 subjects were asked to detect NW and to press a key. The NW elicited central N2 with peak latency about 440 msec. and parietal P3 around 590 msec. Furthermore, smaller and later N2 peaked at about 480 msec. and distributed front-centrally, appeared in response to other categories. Differences of N2 in amplitudes and latencies may reflect differences of mismatches among nonwords, other categories, and the same semantic category.

Temporal relationships between saccade size and lambda complex were studied for four sizes of saccades. Occipital EEGs, time-locked to onset and offset of the saccade, were averaged 50 times for each size of saccade. With averaging time-locked to onset, the latency from onset of the saccade and amplitude increased for later components in proportion to the saccade size, while there was little change in the early positive component. In offset averages, the latency of the later responses from offset of the saccade was constant while the time of the early component from offset of the saccade increased with increasing saccade size. It was concluded that the lambda complex consisted of two groups of components: one associated with onset and one with offset of the saccade. The lambda response itself appears to be the response evoked by the afferent inflow at fixation.

Electrical coupling between areas on the human scalp can be estimated using information transmission as a measure of contingency. Such a measure of coupling changes as a subject’s cognitive operations change. Based on a study of six subjects, detection of cognitively induced changes in coupling is optimum when contingencies are computed from EEG epochs that are about 1.6 sec in duration, sampled every 4 msec with each sample classified as to polarity and first difference.

The purpose of the experiment was to examine the assumption that the lambda response would be associated with offset of the saccade. The occipital EEG and eye movements were recorded under the condition in which the subjects looked at the stimulus object freely. EEGs triggered at onset and offset of saccades were averaged separately by a computer. Lambda responses appeared to be more definite and were larger in amplitude in onset averages than in offset averages. The result showed that the lambda response was associated with offset of the saccade, and not with its onset. It is suggested that the lambda response might be a kind of visual evoked potential elicited by the afferent inflow beginning at fixation pause.

On the basis of the result in earlier studies that the lambda response was associated with offset of the saccade, e.g., onset of the fixation pause, the relationship between the lambda response and the visual information processing load was examined. Eleven subjects were presented simultaneously random patterns including visual signals on a Goldman perimeter and tone pips including auditory signals at random. In the visual task, the subject was instructed to search on the random pattern and detect the visual signals. In the auditory task, he was instructed to listen to tone pips without ceasing eye movements and detect the tone signals. EEGs from Oz and Cz, and the vertical and the horizontal EOGs were recorded. The vector EOG was calculated from the both EOGs for detecting the absolute value of the saccade size. The occipital EEGs time-locked to offset of saccades were averaged 100 times to obtain lambda responses. The vertex EEGs time-locked to tone signals were averaged 100 times to obtain vertex potentials to auditory stimuli (AEP). Amplitudes of the lambda response (NO-P100 and P100-N180) in the visual task were significantly higher than in the auditory task. Amplitudes of AEP (N1 and N1-P2) in the auditory task were enhanced significantly more than in the visual task. The results showed that the lambda response varied with information-processing load. The lambda response can be applicable as an index of visual information processing in eye movement situations.