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The acoustic environment is critical in Air Traffic Control (ATC), as operators exchange information with planes and must also be aware of the occurrence of auditory alarms. In such situations, observing inattentional deafness is likely. In this study, we aimed to identify the physiological indicators of inattentional deafness through the analysis of the P300 evoked potential, known to be an indicator of attention allocation, an important step to a stimulus reaching consciousness. Based on the assumption that the high mental load generated by an ATC task may reduce the alarm detection rate, we wished to test whether this effect would be reflected in the alarm-evoked P300 amplitude. Participants had to perform simulated ATC tasks within the LABY microworld while electroencephalographic (EEG) activity was recorded. Simultaneously to the LABY tasks, participants were asked to respond to target tones (the “alarm”) and to ignore standard tones. Behavioral results showed that 4.6% of alarms were not reported. For these alarm detection failures, the EEG analysis showed a diminution of the P300 amplitude in comparison to a control condition in which participants only focused on the tones. These results suggest that the P300 amplitude seems to be a valid physiological indicator of vulnerability to inattentional deafness in complex environments. Relevant applications include the prevention of alarm omission and the assessment of warning designs.

International audience; The current study examines the role of cognitive and perceptual loads in inattentional deafness (the failure to perceive an auditory stimulus) and the possibility to predict this phenomenon with ocular measurements. Twenty participants performed ATC scenarios – in the Laby ATC-like microworld – guiding one (low cognitive load) or two (high cognitive load) aircraft while responding to visual notifications related to 7 (low perceptual load) or 21 (high perceptual load) peripheral aircraft. At the same time, participants were played standard tones which they had to ignore (probability = 0.80), or deviant tones (probability = 0.20) which they had to report. Behavioral results showed that 28.76 % of alarms were not reported in the low cognitive load condition and up to 46.21 % in the high cognitive load condition. On the contrary, perceptual load had no impact on the inattentional deafness rate. Finally, the mean pupil diameter of the fixation that preceded the target tones was significantly lower in the trials in which the participants did not report the tones, likely showing a momentary lapse of sustained attention, which in turn was associated to the occurrence of inattentional deafness.

International audience; The Air Traffic Control (ATC) environment is complex and safety-critical. Whilst exchanging information with pilots, controllers must also be alert to visual notifications displayed on the radar screen (e.g. warning which indicates a loss of minimum separation between aircraft). Under the assumption that attentional resources are shared between vision and hearing, the visual interface design may also impact the ability to process these auditory stimuli. Using a simulated ATC task, we compared the behavioral and neural responses to two different visual notification designs - the operational alarm that involves blinking colored “ALRT” displayed around the label of the notified plane (“Color-Blink”), and the more salient alarm involving the same blinking text plus four moving yellow chevrons (“Box-Animation”). Participants performed a concurrent auditory task with the requirement to react to rare pitch tones. P300 from the occurrence of the tones was taken as an indicator of remaining attentional resources. Participants who were presented with the more salient visual design showed better accuracy than the group with the suboptimal operational design. On a physiological level, auditory P300 amplitude in the former group was greater than that observed in the latter group. One potential explanation is that the enhanced visual design freed up attentional resources which, in turn, improved the cerebral processing of the auditory stimuli. These results suggest that P300 amplitude can be used as a valid estimation of the efficiency of interface designs, and of cognitive load more generally.

International audience; The Air Traffic Control (ATC) environment is complex and safety-critical; operators work in dynamic situations and must make high-risk decisions under stress and temporal pressure. Whilst exchanging information with the aircrafts under their responsibility via radio, operators must also be alert to the occurrence of auditory alarms, such as the collision avoidance alert or danger area infringement warning. In addition, auditory warnings are increasingly integrated within ATC workstations. The high perceptual load involved in ATC means that controllers’ attention must be shared between several subtasks, with few or no remaining attentional capacity for processing information that is not related directly to the focal task. In this kind of situation, the likelihood of a controller failing to become aware of an auditory alarm, i.e. inattentional deafness, is high. Characterizing physiological symptoms associated with inattentional deafness would enable online detection of the phenomenon in safety-critical situations (nuclear power station supervision, piloting or air traffic control). We designed an ecological ATC thanks to the simulation environment called the “LABY” microworld. Twenty participants were required to guide one (low cognitive load) or two planes (high cognitive load) around a given route, while dealing with visual notifications relating to peripheral aircrafts. During the task, participants were played either standard tones which they were told to ignore, or deviant tones (“the alarm”, probability = 0.20) which they were told to report (20 alarms per scenario). We hypothesized that the detection rate of auditory alarms will decrease with cognitive workload. In order to explore this possibility, Behavioral results showed that 28.8% of alarms were not reported when guiding one plane, and up to 46.2% when guiding two planes (high load). The cognitive load increase led to a reduced visual notification detection rate, but the performance to guiding the central aircrafts was maintained, as well as the reaction times to report auditory alarms when perceived. This high rate of inattentional deafness is essential to further physiological studies on alarm omission in aeronautics, such as ERP or eye movement analysis. Potential applications are related to the integrative online detection and prevention of alarm omission, and the online measurement of workload in ecological situation.

Operating an aircraft is cognitively challenging: pilots have to control the plane and must remain responsive to potential verbal-auditory stimuli (e.g. Air Traffic Control Communication) and auditory alerts (e.g. Terrain Awareness and Warning System). Fifteen participants had to control an aircraft in order to target one of three differently-colored aircrafts displayed on a computer screen. The name of the color (written in black ink) corresponding to the aircraft to target was displayed in the center of the screen. Simultaneously with the onset of the written name of the color, a spoken color name distractor that participants had to ignore was played. This auditory distractor was either congruent (10%, spoken color name matched the written color) or incongruent (10%, spoken color name did not match the written color). The task difficulty varied in terms of working memory load with an n-back-like sub-task. In the low load condition, participants had to target the aircraft corresponding to the currently presented written instruction (n = 0). In the high load condition, participants had to target the aircraft corresponding to the instruction presented two trials before (n = 2). Behavioral analysis showed that increased mental workload provoked a decrease in piloting performance, i.e. participants tended to forget the correct instruction. On the physiological level, EEG/ERP measurements related to instructions showed that increased mental workload was accompanied by lower P3b amplitude. We assume that the lower P3b amplitude reflects the depletion of the cognitive resources allocated to the processing of the instructions. These results suggest that P3b can be a relevant indicator of the openness of the system to sudden and unexpected critical stimuli such as auditory alerts.