Sustained training with novel distractors attenuates the behavioral interference of emotional pictures but does not affect the electrocortical markers of emotional processing

Abstract

Introduction: Research has recently shown that behavioral interference prompted by emotional distractors is subject to habituation when the same exemplars are repeated, but promptly recovers in response to novel stimuli. The present study investigated whether prolonged experience with distractors that were all novel was effective in shaping the attentional filter, favoring stable and generalizable inhibition effects.

Methods: To test this, the impact of emotional distractors was measured before and after a sustained training phase with only novel distractor pictures, and that for a group of participants depicted only a variety of neutral contents, whereas a different group was exposed only to emotional contents.

Results: Results showed that emotional interference on reaction times was attenuated after the training phase (compared to the pre-test), but emotional distractors continued to interfere more than neutral ones in the post-test. The two groups did not differ in terms of training effect, suggesting that the distractor suppression mechanism developed during training was not sensitive to the affective category of natural scenes with which one had had experience. The affective modulation of neither the LPP or Alpha-ERD showed any effect of training.

Discussion: Altogether, these findings suggest that sustained experience with novel distractors may attenuate attention allocation toward task irrelevant emotional stimuli, but the evaluative processes and the engagement of motivational systems are always needed to support the monitoring of the environment for significant cues.

Keywords: Alpha-ERD; LPP; behavioral interference; emotional scenes; training.

Figure 1

Schematic diagram showing the sequence of events in the present study. The trial sequence was the same over the whole experiment, with an initial dark-gray blank screen appearing for 500 msec, followed by a Gabor patch (target stimulus) presented for 150 msec. In half of the trials with a random occurrence, one picture of a natural scene appeared as a distractor stimulus simultaneously with the Gabor patch, flanking it to the left or right, and stayed on the screen until the Gabor patch disappeared. Participants were instructed to focus their attention on the Gabor patch and to determine its orientation (vertical or horizontal) by pressing one of two buttons while ignoring the distracting scenes. In the pre-test as well as in the post-test distractors were pictures depicting both emotional and neutral contents. In the practice phase, distractors were only neutral pictures for group 1 or only emotional pictures for group 2.

Figure 2

The effects of distractor occurrence on the LPP amplitude. (A) Grand-averaged ERP waveforms (average across the sensor cluster) for emotional and neutral distractors in the pre-test block. Insets show the scalp topography (450–900 msec) of the difference in the LPP between emotional and neutral distractors. (B) The bar graphs show the mean of the LPP amplitude (window 450–900 ms) for distractor-absent, emotional, and neutral distractors in the pre- and the post-test.

Figure 3

The effects of distractor occurrence on the Alpha-ERD. (A) Time-frequency plot of the emotional-neutral difference at occipitotemporal sensor sites, regardless of distractor laterality. (B) Topography of alpha power changes (450–900 ms window) for emotional and neutral distractors appearing on the left or on the right of the visual hemifield. (C) The bar graphs show the mean of the alpha power changes (window 450–900 ms) for distractor-absent, emotional and neutral distractors in the pre- and the post-test.

Figure 4

RTs in the discrimination orientation task for each trial type. Behavioral interference is plotted as a function of block, showing that the RT slowdown was maximum with the occurrence of emotional distractors, compared with neutral distractors or trials with no distractors. The emotional interference was clearly attenuated in the post-test. Error bars show ±1 SEM calculated within participants using the method of O’Brien et al. (2014). The inset shows the single subject plots of the emotional interference (emotional minus neutral) in the pre and post-test for each training group.