Acute Stress and Perceptual Load Consume the Same Attentional Resources: A Behavioral-ERP Study.

Stress and perceptual load affect selective attention in a paradoxical manner. They can facilitate selectivity or disrupt it. This EEG study was designed to examine the reciprocal relations between stress, load and attention. Two groups of subjects, one that performed the Trier Social Stress Test (TSST), and a control group, were asked to respond to a target letter under low and high perceptual load in the absence or presence of a distractor. In the control group, the distractor increased response times (RTs) for high and low load. In the TSST group, distractor increased RTs under low load only. ERPs showed that distractor's presentation attenuated early visual P1 component and shortened its latency. In the TSST group, distractor reduced P1 component under high load but did not affect its latency. Source localization demonstrated reduced activation in V1 in response to distractors presence in the P1 time window for the TSST group compared to the control group. A behavioral replication revealed that in the TSST group distractors were less perceived under high load. Taken together, our results show that stress and perceptual load affect selectivity through the early stages of visual processing and might increase selectivity in a manner that would block conscious perception of irrelevant stimuli

Source localization by sLORTA in four time windows.

<p>Graphical representations of the sLORETA results comparing the amplitudes of ERPs elicited by picture under high load condition in control and TSST group, in the four time-windows. Areas with significantly increased activity (yellow) and significantly decreased activity (light blue) due to picture presence, are presented (<i>p</i> < .05). Less activation in V1 was observed in the TSST group due to picture presence early at ~100ms after stimulus onset.</p

The emotional perceptual load task.

<p>The emotional perceptual load task.</p

Means and SE of amplitude’s peak and latency for each ERP component.

<p><b>A</b>: The mean amplitudes' peak for occipito-perietal P1, N1, P2 and LPP, (lower) and frontal N1, P1, N2 and LPP (upper), component as a function of perceptual load and picture presence in each group. <b>B:</b> The mean amplitudes’ latency for the occipito-perietal P1, N1, P2 and LPP, (lower) and frontal N1, P1, N2 and LPP (upper), component as a function of perceptual load and picture presence in each group. Bars represent SE.</p

F-statistics of each effect analysis in control and TSST groups.

<p>F-statistics of each effect analysis in control and TSST groups.</p

Salivary cortisol levels.

<p>ANOVA repeated measures indicated a significant increase in cortisol levels in the TSST group (n = 11) during the task compared to before the task <i>p <</i> .<i>01</i> but, not in the control group (n = 5), <i>n</i>.<i>s</i>.. The bars represent standard errors (SE).</p

Grand averaged representative potentials.

<p>Event-related potentials at frontal (upper; F1, F2, F3, F4, F5, F6, F7, F8 and Fz) and occipito-parietal (lower: O1, O2, Oz, POz, PO3, PO4 and PO8) areas elicited by each of the four conditions: low load no picture, low load picture, high load no picture and high load picture, are depicted for participates in Control (left; <i>n</i> = 17) and TSST (right; <i>n</i> = 17) groups. Arrow represents the beginning of the trial. Latency and amplitude peak were calculated for four occipito-parietal components: P1, N1, P2, LPP, and for four frontal components: N1, P1, N2 and LPP.</p

Behavioral response time results.

<p>ANOVA repeated measures indicated a significant three-way interaction picture valence X load X group, <i>p <</i> .05. In the control group (n = 17), negative pictures under low perceptual load increased RTs compared to neutral pictures, but not under high perceptual load. In addition, picture presence (negative and neutral) increased RTs in both low and high perceptual load. In the TSST group (n = 17), RTs were not increased due to negative pictures under both low and high perceptual loads; however, picture presence increased RTs in low load but not in high load conditions. In both groups RTs were generally slower under high load than in low load condition. The error bars represent SE. <i>Note</i>: <i>RT = response time in ms</i>.</p