Fixation-related Potentials Research Articles

Estimation of an unexpected-overlooking error by means of the single eye fixation related potential analysis with wavelet transform filter

An unexpected-overlooking error that caused failure to notice near the peripheral vision is one of the accident factors in driving behavior. We estimated how the unexpected-overlooking error affected the amplitude of the lambda wave in the eye fixation related potential (EFRP). Four subjects participated in the experiment. Each subject was required press the right or left switch according to the given task, which was that he/she pressed the right switch when the blue dot appeared in the right detected area or he/she pressed the left switch when the red dot appeared in the right. The single trial data from Pz, which referred to both earlobes, were analyzed by means of a wavelet transform (WT) filter. The difference of the lambda amplitude between the corrected data was applied for analysis of variance. Three subjects showed a significant effect ( P<0.01 or P<0.05), and the remaining one subject did not show a significant consequence of only two errors. The unexpected-overlooking errors had a low amplitude compared to the mean of amplitude throughout the task. It was concluded that the amplitude of the lambda wave might reflect the attention level of a subject.

Eye fixation related potentials in a proof reading task

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.

ＶＤＴ作業時の眼球停留関連電位の変動

ＶＤＴ作業時の眼球停留関連電位の変動

VDT作業時の眼球停留関連電位の変動

VDT作業時の眼球停留関連電位の変動

Brain potentials associated with eye fixations during visual tasks under different lighting systems

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.

Simultaneous identification of eye fixation related potentials and reaction related potentials from single-trial signals.

To obtain the effective components from event related potentials (ERPs), it has been necessary to average the waveforms of several trials. ERP data reflect the psychophysiological state of a subject. Time variation is an important feature in ERP analysis, and so the single-trial method is required. A method is proposed to identify simultaneously both eye fixation related potentials (EFRPs) and reaction related potentials (RRPs) using wavelength transforms. The EFRP is an ERP associated with saccadic eye movement. The RRP is defined as a component similar to P300 gained from the reaction signal. Six subjects participate in the oddball task. The task takes 30 min for each subject. Electroencephalograms (EEGs), electro-oculograms (EOGs) and electromyograms (EMGs) are simultaneously recorded. The EFRP is extracted for the offset of saccade from EOG, and the RRP is extracted for the onset of reaction from EMG. The results show that the estimated waveforms described well each of the components in the EFRP and RRP. Moreover, the simulation results show that the amplitudes of the lambda wave are estimated to within an error of 4%, and those of the latencies are within 0.4%, with an SNR of 4.5dB. Those of P300 were 11 and 4%, respectively. The reliability of the method is proved to be sufficient for estimating ERPs.

照明環境下における眼球停留関連電位の変動の適応型フィルターによる評価

照明環境下における眼球停留関連電位の変動の適応型フィルターによる評価

作業環境の照度変化時の眼球停留関連電位 (ラムダ反応) の変動

作業環境の照度変化時の眼球停留関連電位 (ラムダ反応) の変動