Edited by: Nuno Sousa, University of Minho, Portugal
Reviewed by: Gustav Schelling, Ludwig-Maximilians-Universität München, Germany; Etsuro Ito, Waseda University, Japan
*Correspondence: Rong Cao
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Inhibition of return (IOR) is an important effect of attention. However, the IOR of emergency managerial experts is unknown. By employing emergency and natural scene pictures in expert-novice paradigm, the present study explored the neural activity underlying the IOR effects for emergency managerial experts and novices. In behavioral results, there were no differences of IOR effects between novices and emergency managerial experts, while the event-related potentials (ERPs) results were different between novices and experts. In Experiment 1 (novice group), ERPs results showed no any IOR was robust at both stimulus-onset asynchrony (SOA) of 200 ms and 400 ms. In Experiment 2 (expert group), ERPs results showed an enhanced N2 at SOA of 200 ms and attenuated P3 at cued location in the right parietal lobe and adjacent brain regions than uncued location at SOA of 200 ms. The findings of the two experiments showed that, relative to the novices, IOR for the emergency managerial experts was robust, and dominated in the right parietal lobe and adjacent brain regions, suggesting more flexible attentional processing and higher visual search efficiency of the emergency managerial experts. The findings indicate that the P3, possible N2, over the right parietal lobe and adjacent brain regions are the biological indicators for IOR elicited by post-cued emergency pictures for emergency managerial experts.
Attention orients directly the most relevant stimuli and ignores irrelevant stimuli to given targets, and is thought to play an important role in human information processing (Eriksen and Hoffman,
Previous studies have suggested that it takes at least a decade to be an expert in a specific domain (Bryan and Harter,
To date, the issue for neural substrate of IOR effects has been examined by prior event-related potentials (ERPs) studies, and the ERPs technique has been proved to be a useful approach to examining the neural mechanism underlying the IOR for its high temporal resolution. N1, N2 and P3 are components of ERPs. N1 is a negative-going evoked potential, peaking between 150 and 200 ms after the onset of a stimulus in posterior scalp and distributing over the parietal and occipital lobe, which reflects discrimination process (Vogel and Luch,
Although prior studies have examined cognitive and neural differences between experts and novices in some domains, the neural mechanisms underlying IOR for the managerial experts and novices remain unclear. Moreover, the brain activities underlying IOR effects for emergency managerial experts and novices are totally lack of understanding. In context of crisis, the rapid process is essential for emergency managerial experts. Because of expert judgments being very rapid (Gobet and Simon,
Twenty-five volunteers of novices (3 females and 22 males, mean age 26.24 years, range from 20 years to 35 years old) participated in Experiment 1, consisting of general college students from the Northwest university and civil servants. They did not perform in related work of emergency management. Only one of them was left-hand. All participants reported normal or corrected-to-normal vision and had no history of current or past neurological or psychiatric illness and took no medications known to affect the central nervous system. Furthermore, written informed consent was obtained from all the participants before the beginning of experiment, and the experiment was approved by the Departmental Research Ethics Committee.
The stimuli of the present experiment consist of two kinds of pictures: emergency and landscape pictures. Two-hundred and fifty-six emergency pictures contain four types of crisis events according to the Emergency Response Law of the People’s Republic of China, including natural disaster pictures (such as earthquake, flood pictures etc.), accidental disaster pictures (such as air crash, explosion pictures etc.), public health event pictures (such as SARS epidemic, pandemic influenza pictures etc.), and social security event pictures (such as attack terrorism, air raid pictures etc.). Two-hundred and fifty-six landscape pictures, which matched with the emergency pictures in perceptual features, such as size, pixel and so on, were selected as stimuli. Because pictures could automatically attracts individuals’ attention when a cue appears in visual field (Gutiérrez-Domínguez et al.,
There was instruction before the beginning of the experiment. Participants were seated in a dimly illuminated, sound attenuated room, faced with a computer screen at a distance of 75 cm. The computer monitor screen (CRT: 1024 × 768) was placed and all stimuli were presented within 6° of visual angle in two sides of the screen. The background color of the monitor was black. At the start of each trial, a small white cross lasting 750 ms as to fixation was presented on the computer screen. Participants were instructed to maintain their eyes on central fixation during the task performance. After this, two kinds of pictures (emergency pictures and landscape pictures) would be presented at the same time, and the duration was 200 ms. Following the pictures, two intervals of 0 ms or 200 ms (SOA = 200 ms or 400 ms) were randomly presented. When the intervals disappeared, a rectangle or a triangle as a target would appear at random. Participants were asked to responsed to the target (rectangle or triangle) irrespective of its location by pressing one key as quickly and accurately as possible. If the target was a rectangle, press “F” button; otherwise, press “J” button. The assignment of response key to each condition was counter-balanced across participants. A target was not disappeared until a response was made or for a maximum of 2000 ms. The inter-trial-interval (ITI) was a empty screen that randomly varied between 500 ms and 800 ms.
The whole experiment was divided into two sections, practice and experiment. There were 10 trials in practice section, and the task would cycle until the participants understood the experiment procedure. The experiment section contained 512 trials and was divided into four blocks of 128 trials. The different conditions (SOA = 200 ms or 400 ms) were randomly intermixed in each block. The experiment lasted about 25 min. Short breaks (the lengths of breaks were up to each participant) were allowed between blocks. The typical trial is shown in Figure
The RTs and error rates of target stimuli in all conditions were on-line recorded by E-Prime software (Version 2.0). Only RTs of correct responses were used for data analysis. We eliminated the trials in which RTs were less than 100 ms or greater than 1000 ms (Gouzoulis-Mayfrank et al.,
The electroencephalogram (EEG) activity was continuously recorded and off-line data analyses were employed with Neurolab system by a set of 64 scalp Ag/AgCI electrodes placed according to the 10/20 international system. The tip of nose was used as reference during recording, and was re-referenced to M1 and M2 off-line. Vertical and horizontal electrooculogram (HEOG and VEOG) were recorded through electrodes placed on the bilateral external canthi and the left infraorbital and supraorbital areas. Electrode impedances were kept below 5 kΩ. The sampling rate was 500 Hz/channel. The EEG signals of each participant were continuously recorded by amplifier system and filtered online with a 0.05–100 Hz band pass. The data of ERPs were baseline corrected and segmented in epochs of 1000 ms post stimulus and 200 ms prior to stimulus onset. Any electrodes with amplitudes beyond ±100 μυ were excluded from averaging, and the averaged ERPs were low-pass filtered at 30 Hz (24 dB/octave).
In the present experiment, five participants were eliminated according to the criteria of exclusion in behavioral and ERPs data analyses mentioned above. The remaining participants were 20 novices in crisis management domain.
Mean RTs and error rates for all conditions are calculated for each participant and submitted to a 2 (SOA: 200 ms vs. 400 ms) × 2 (Cue validity: cued vs. uncued) repeated measures analysis of ANOVA (see Table
SOA (ms) | Cue validity (M ± SD) | Mean RTs (M ± SD) | Error rates (%) |
---|---|---|---|
200 | cued | 537.52 ± 71.32 | 1.52 ± 1.39 |
uncued | 532.36 ± 67.89 | 1.60 ± 2.25 | |
400 | cued | 515.63 ± 77.15 | 1.95 ± 1.89 |
uncued | 509.20 ± 72.21 | 1.68 ± 1.44 |
The grand-average ERP waveforms for all conditions are presented in Figure
N1 amplitude was measured by mean detection within a time window from 110 ms to 180 ms at CP3, CPZ, CP4, P3, PZ, P4, PO3, POZ and PO4 electrode sites. The N1 amplitude for all conditions were analyzed by employed an ANOVA of 2 (SOA: 200 ms vs. 400 ms) × 2 (Cue validity: cued vs. uncued) × 3 (Hem: left vs. central vs. right hemisphere) × 3 (Site: CP3/CPZ/CP4 vs. P3/PZ/P4 vs. PO3/POZ/PO4) repeated measures analysis.
The main effect of SOA was significant (
N2 amplitude was calculated as the mean amplitude within a time window from 210 ms to 290 ms at the same electrode sites as in N1. The experimental design for N2 was identical with that for N1.
The main effect of SOA was significant (
P3 amplitude was calculated as the mean amplitude within a time window from 290 ms to 520 ms at the same electrode sites as in N1. The experimental design for P3 was identical with that for N1.
The main effect of SOA was significant (
Experiment 1 revealed that there was an IOR effect for emergency pictures at SOA of 400 ms for novices. Using the same task of Experiment 1, the unique feature in Experiment 2 was the participants consisting of emergency managerial experts, thus all methods except participants in Experiment 2 were as the same as Experiment 1.
Twenty-five volunteers of emergency managerial experts (1 female and 24 males, mean age: 44.08 years, range from 33 years to 58 years old; mean working years: 10.8, range from 2 to 34 years) participated in Experiment 2 and one of them was a left-hand. All of them were civil servants and engaged in emergency management. Other characteristics of participants were identical with the participants in Experiment 1. Written informed consents were obtained from all the participants before the experiment. The experiment was approved by the Departmental Research Ethics Committee. Five participants were eliminated according to the criteria of rejection in behavioral and ERPs data analyses mentioned above. Therefore, the remaining participants were 20 emergency managerial experts.
Mean RTs and error rates for all conditions are presented in Table
SOA (ms) | Cue validity (M ± SD) | Mean RTs (M ± SD) | Error rates (%) |
---|---|---|---|
200 | cued | 586.80 ± 49.58 | 1.44 ± 1.55 |
uncued | 577.01 ± 48.03 | 1.41 ± 1.28 | |
400 | cued | 545.98 ± 54.88 | 1.56 ± 1.48 |
uncued | 547.29 ± 54.48 | 1.56 ± 2.01 |
The grand-average ERP waveforms for all conditions are presented in Figure
N1 amplitude was calculated as the mean amplitude. The time window for mean detection, the electrode sites and the experimental design for N1 in Experiment 2 were identical with those for N1 in Experiment 1.
The main effects of SOA, Cue validity and Hem were not significant (
N2 amplitude was calculated as the mean amplitude. The time window for mean detection, the electrode sites and the experimental design for N2 in Experiment 2 were identical with those for N1 in Experiment 1.
The main effect of SOA was significant (
P3 amplitude was calculated as the mean amplitude. The time window for mean detection, the electrode sites and the experimental design for P3 in experiment 2 were identical with those for N1 in Experiment 1.
The main effects of SOA, Cue validity, Hem and Site were not significant (
The aim of the present study was to explore the neuro-cognitive mechanism underlying IOR effects for emergency managerial experts and novices. The major findings were provided by behavioral data and ERPs data. In behavioral level, the IOR effects were robust at SOA of 200 ms and 400 ms for the novices and emergency managerial experts. The ERPs results suggested no IOR effects on N1, N2 and P3 amplitudes for the novices. However, the IOR effects on P3, possible on N2 amplitudes were found for the emergency managerial experts, showing a larger N2 and a smaller P3 evoked by targets in cued trials than those in uncued trials over the right parietal lobe and adjacent brain regions at SOA of 200 ms.
The behavioral data of experiments indicated that there were no differences of IOR effects for emergency pictures at SOA of 200 ms and 400 ms between two groups of participants. Therefore, behavioral data cannot provide indexes to distinct the IOR effects between the novices and emergency managerial experts. Except the IOR effects of behavioral data, the brain activities underlying IOR effects, which were reflected by the ERPs data in the present study, could provide some evidence to differentiate the IOR effects between the novices and experts.
For the novices, no IOR effects on N1, N2 and P3 were found, which were inconsistent with the studies by McDonald et al. (
For the emergency managerial experts, no IOR robust on N1 component was found. It was the same with the ERPs data for novice, and was similar to the prior findings by Hopfinger and Mangun (
In conclusion, based on the ERPs data, there is a robust IOR at SOA of 200 ms for the emergency managerial experts, not for the novices; P3 and possible N2 components in the right parietal lobe and adjacent brain regions are the biological indicators for IOR about emergency pictures for emergency managerial experts.
In summary, the purpose of the present study was to explore the IOR effects between emergency managerial experts and novices. In the present study, the expert-novice paradigm and emergency pictures were used. Due to the different experiences with emergency management between participants, the emergency managerial experts have more experiences with emergency stimuli than novices do. So the emergency pictures used by the study might cause increases in stress hormones (in particular cortisol) with pronounced cognitive and behavioral effects including memory consolidation and retrieval in the novices, which could might cause emotional reactions of the novices and influence their attentional processing. To the extent, a limitation of the study is to make sure whether the effects of stress hormones impact the experimental results. For this reason, a simple saliva cortisol measurement for participants could have helped to clarify this issue in further studies.
RC finished the article. LW and SW collected and analyzed the data.
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
This study reported here was supported by Social Science Foundation of China called the study about the emergency decision-making pattern of leaders under crisis (13BGL074).