Eye-Fixation-Related Potentials (EFRPs) As a Predictor of Human Error Occurrences During a Visual Inspection Task.

Estimation of human attentional states using an electroencephalogram (EEG) has been demonstrated to help prevent human errors associated with the degradation. Since the use of the lambda response -one of eye-fixation-related potentials time-locked to the saccade offset- enables such estimation without external triggers, the measurements are compatible for an application in a real-world environment. With aiming to apply the lambda response as an index of human errors during the visual inspection, the current research elucidated whether the mean amplitude of the lambda response was a predictor of the number of inspection errors. EEGs were measured from 50 participants while inspecting the differences between two images of the circuit board. Twenty percent of the total number of image pairs included differences. The lambda response was obtained relative to a saccade offset starting a fixation of the inspection image. Participants conducted four sessions over two days (625 trials/ session, 2 sessions/ day). A Poisson regression of the number of inspection errors using a generalized linear mixed model showed that a coefficient of the mean amplitude of the lambda response was significant , suggesting that the response has a role in th$(\hat \beta = 0.24,p < 0.01)$e prediction of the number of human error occurrences in the visual inspection.

Functional Connectivity and Networks Underlying Complex Tool-Use Movement in Assembly Workers: An fMRI Study.

The aim of this study was to identify the functional connectivity and networks utilized during tool-use in real assembly workers. These brain networks have not been elucidated because the use of tools in real-life settings is more complex than that in experimental environments. We evaluated task-related functional magnetic resonance imaging in 13 assembly workers (trained workers, TW) and 27 age-matched volunteers (untrained workers, UTW) during a tool-use pantomiming task, and resting-state functional connectivity was also analyzed. Two-way repeated-measures analysis of covariance was conducted with the group as a between-subject factor (TW > UTW) and condition (task > resting) as a repeated measure, controlling for assembly time and accuracy as covariates. We identified two patterns of functional connectivity in the whole brain within three networks that distinguished TW from UTW. TW had higher connectivity than UTW between the left middle temporal gyrus and right cerebellum Crus II (false discovery rate corrected p-value, p-FDR = 0.002) as well as between the left supplementary motor area and the pars triangularis of the right inferior frontal gyrus (p-FDR = 0.010). These network integrities may allow for TW to perform rapid tool-use. In contrast, UTW showed a stronger integrity compared to TW between the left paracentral lobule and right angular gyrus (p-FDR = 0.004), which may reflect a greater reliance on sensorimotor input to acquire complex tool-use ability than that of TW. Additionally, the fronto-parietal network was identified as a common network between groups. These findings support our hypothesis that assembly workers have stronger connectivity in tool-specific motor regions and the cerebellum, whereas UTW have greater involvement of sensorimotor networks during a tool-use task.

Signal correlation between wet and original dry electrodes in electroencephalogram according to the contact impedance of dry electrodes.

The development of dry electroencephalogram (EEG) electrodes is a topic of interest. A benefit of using dry EEG electrodes is that they do not require any skin preparation. As a result, the condition of the skin with which the dry electrodes come in contact is always different among experiments. Thus, in order to quantify the performance of EEG recordings using dry electrodes, we need an indicator of signal quality for these electrodes. In this study, we showed that signal quality changed according to the contact impedance between the skin and our dry electrodes. The results indicate that our dry electrodes could record EEG signals with high quality when the contact impedance was less than 350 kµ. However, contact between the skin and an electrode often changes even during experiments, and therefore, we contend that the contact impedance should be reduced to less than 300 kµ for safety reasons.