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Vigilance Enhancement using Challenge Integration in a Naturalistic Surveillance Task

Indu P. Bodala1, 2*, ANASTASIOS BEZERIANOS1, 3, Nitish V. Thakor1, 2 and Hasan AL-Nashash4
  • 1 National University of Singapore, Singapore Institute for Neurotechnology (SINAPSE), Singapore
  • 2 National University of Singapore, NUS Graduate School for Integrative Sciences and Engineering (NGS), Singapore
  • 3 University of Patras, Dept. of Medical Physics, School of Medicine, Greece
  • 4 American University of Sharjah, Department of Electrical Engineering, College of Engineering, United Arab Emirates

Background Lapses in attention are ubiquitous and degrade the performance during tasks that require maintenance of sustained attention or vigilance over long duration such as monitoring, surveillance, etc. Our capacity to maintain sustained attention is limited and is influenced by several factors such as sleep, stress levels, motivation levels, stimulus properties, etc. [1]. Failures in sustained attention can result in dangerous consequences. It is therefore important to develop strategies that can enhance vigilance and integrate them into everyday systems. In this study, vigilance level in a naturalistic surveillance task was manipulated by modifying the stimulus properties to create challenging task conditions [2]. As supported by ‘underload’ hypothesis [3], challenge integration leads to higher sustained attention. EEG and eye tracking data were collected and analyzed. We found that the vigilance level was significantly higher for challenge integrated phase compared to that of monotonous phase. Approach An industrial surveillance task was designed where the subjects have to identify an animated human-like target intruder wearing a certain military uniform among other animated distractors. The experiment was divided into three phases. The first phase is a monotonous target detection phase where the target appeared once in 60-90 seconds. This phase is intended to make the subjects less vigilant and goes on for duration of 15 minutes. Then we activate simulated rain in the environment that acts as a challenging visual stimulus. This challenge was given intermittently for a duration of 3 minutes with an interval of 2 minutes between successive challenge stimuli. This is termed as phase 2 and continued for a duration of 20 minutes which implies that there are four successive periods of 3 minutes with challenge and 2 minutes without challenge. Phase 3 is again similar to phase 1 with no challenge stimulus. Target appearance rate was kept constant throughout the experiment. 64 channel EEG and eye tracking data were collected and analyzed from twelve healthy subjects [2]. Results EEG We analyzed the variations in relative delta power, frontal midline theta and the ratio of frontal theta to parietal alpha which were well founded in literature as the indices that can measure vigilance level or task engagement [4-6]. A reverse change in the dynamic of relative delta power was found due to challenge integration for the electrodes on the frontoparietal and occipital cortices (p < 0.05). During monotonous phase, the relative delta power increased indicating vigilance decrement whereas it decreased when challenge was activated and was maintained constant after the removal of challenge. Similar but opposite trend was observed in the case of frontal midline theta (F3, F2, F4, F6, FC3, FC4 and FC6) and the ratio of frontal theta power (F3, F2, F4, F6, FC3, FC4 and FC6) to parietal alpha power (P3, P4, P5, P6, P7 and P8) (p < 0.05 in both cases). These measures decreased with vigilance decrement and increased during the challenge integrated phase. The means and standard errors of relative delta, frontal midline theta and ratio of frontal theta to parietal alpha during phase 1, phase 2 and phase 3 are plotted in figure 1. Eye tracking Eye movements provide a window into brain processes especially attention and planning in visual tasks. Statistically significant changes were found in the case of saccade amplitude, saccade velocity and eye blink rate due to challenge integration. The saccadic variables, amplitude and velocity, decreased with vigilance decrement and increased during challenge integrated phase whereas the opposite trend was observed in the case of blink rate (p <0.05 in all cases). These observations were also supported by the studies which found similar changes due to vigilance decrement [7, 8]. We also observed statistically significant correlations between EEG and eye tracking measures. The means and standard errors of saccade velocity, saccade amplitude ad blink rate during phase 1, phase 2 and phase 3 are plotted in figure 2. Discussion In our previous studies, it was found that noisy visual stimuli increase mental workload [9]. Hence, the increase in sustained attention due to integrated challenge can be thought of as a valid strategy that can be supported by ‘underload’ hypothesis which explains that vigilance decrement is due to the withdrawal of attentional resources due to insufficient mental workload [3]. However, the maintenance of vigilance level for a long duration due to challenge integration or even after the removal of the challenge has yet to be investigated. This may also requires us to take into account the ‘overload’ hypothesis which explains that vigilance decrement is due to the depletion of attentional resources due to accumulated fatigue [3]. Moreover, the challenge stimulus is given to all the subjects at fixed time intervals. For the subjects to sense the attention lapses and correct them, the subjects need to have a robust and sensitive feedback signal that is individualized and can reflect moment-to-moment sustained attention fluctuations [10]. In addition, the changes in top-down endogenous factors such as motivation, sleep and stress which contribute to maintenance of vigilance level have also to be well understood. It may prove even more effective to develop strategies that can influence top-down sustained attention such as using reward/punishment strategies to manipulate motivation [11]. These aspects will be studied in detail in our future experiments. Conclusion This study helped us to understand the vigilance mechanisms in naturalistic tasks and the role of bottom-up factors such as stimulus properties in maintaining vigilance using EEG and eye tracking data. This knowledge is important to develop non-invasive task strategies that can be integrated into work setting for the enhancement of the personnel’s efficiency.

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Keywords: Vigilance enhancement, cognitive enhancement, EEG power, eye tracking, visual search

Conference: SAN2016 Meeting, Corfu, Greece, 6 Oct - 9 Oct, 2016.

Presentation Type: Oral Presentation in SAN 2016 Conference

Topic: Oral Presentations

Citation: Bodala IP, BEZERIANOS A, Thakor NV and AL-Nashash H (2016). Vigilance Enhancement using Challenge Integration in a Naturalistic Surveillance Task. Conference Abstract: SAN2016 Meeting. doi: 10.3389/conf.fnhum.2016.220.00028

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Received: 24 Jul 2016; Published Online: 30 Jul 2016.

* Correspondence: Ms. Indu P Bodala, National University of Singapore, Singapore Institute for Neurotechnology (SINAPSE), Singapore, Singapore, ipb29@cl.cam.ac.uk