A negative emotional state impairs individuals' ability to filter distractors from working memory: an ERP study

Abstract

Capacity-limited visual working memory (VWM) requires that individuals have sufficient memory space and the ability to filter distractors. Negative emotional states are known to impact VWM storage, yet their influence on distractor filtering within VWM remains underexplored. We conducted direct neural measurement of participants (n = 56) who conducted a lateralized change detection task with distractors, while manipulating the emotional state by presenting neutral or negative images before each trial. We found a detrimental effect of distractors on memory accuracy under both neutral and negative emotional states. Using the event-related potential (ERP) component, contralateral delay activity (CDA; sensitive to VWM load), to observe the VWM load in each condition, we found that in the neutral state, the participants showed significantly higher late CDA amplitudes when remembering 4 targets compared with 2 targets and 2 targets with 2 distractors but no significant difference when remembering 2 targets compared with 2 targets with 2 distractors. In the negative state, no significant CDA amplitude differences were evident when remembering 4 targets and 2 targets, but CDA was significantly higher when remembering 2 targets with 2 distractors compared with 2 targets. These results suggest that the maximum number of items participants could store in VWM was lower under negative emotional states than under neutral emotional states. Importantly, the participants could filter out distractors when in a neutral emotional state but not in a negative emotional state, indicating that negative emotional states impair their ability to filter out distractors in VWM.

Keywords: Contralateral delay activity; Distractor filtering; Negative emotion; Visual short-term memory.

Fig. 1

Flowchart of the main task. A neutral or negative image was presented before each trial in the corresponding emotional state block of the lateralized change-detection task. The sequence of emotional state blocks was counterbalanced across the participants. The flowchart depicts the scenario with red targets and blue distractors. The participants were instructed to determine whether the orientations of the red rectangles (targets) changed in the cued hemifield. The cued hemifield was the left hemifield in half of the trials (as shown in the flowchart), and the right hemifield in the remaining trials. The participants were instructed to ignore the blue rectangles (distractors). The memory condition varied with a two-target array (2T), a two-target array with two distractors (2T2D), and a four-target array (4T)

Fig. 2

Results of each experimental condition. (A) Accuracy results (mean and standard error of the mean) are presented separately for the neutral emotional state (left) and negative emotional state (right) across different memory conditions. (B) Whole CDA amplitude (300–1000 ms) results for the neutral emotional state (left) and negative emotional state (right) are shown separately under different memory conditions. (C) Early CDA amplitude (300–600 ms) results for the neutral emotional state (left) and negative emotional state (right) are shown separately under different memory conditions. (D) Late CDA amplitude (700–1000 ms) results for the neutral emotional state (left) and negative emotional state (right) are shown separately under different memory conditions. Error bars represent the standard error. (E) Difference waveforms (contralateral waves minus ipsilateral waves) of average ERPs are depicted for different memory conditions in the neutral emotional state. (F) Difference waveforms of average ERPs are presented for different memory conditions in the negative emotional state. The waveforms are time-locked to the onset of the memory array (y-axis at time zero)