The oscillatory fingerprints of self-prioritization: Novel markers in spectral EEG for self-relevant processing

Self-prioritization is a very influential modulator of human information processing. Still, little is known about the time-frequency dynamics of the self-prioritization network. In this EEG study, we used the familiarity-confound free matching task to investigate the spectral dynamics of self-prioritization and their underlying cognitive functions in a drift-diffusion model. Participants (N = 40) repeatedly associated arbitrary geometric shapes with either "the self" or "a stranger." Behavioral results demonstrated prominent self-prioritization effects (SPEs) in reaction time and accuracy. Remarkably, EEG cluster analysis also revealed two significant SPEs, one in delta/theta power (2-7 Hz) and one in beta power (19-29 Hz). Drift-diffusion modeling indicated that beta activity was associated with evidence accumulation, whereas delta/theta activity was associated with response selection. The decreased beta suppression of the SPE might indicate more efficient sensorimotor processing of self-associated stimulus-response features, whereas the increased delta/theta SPE might refer to the facilitated retrieval of self-relevant features across a widely distributed associative self-network. These novel oscillatory biomarkers of self-prioritization indicate their function as an associative glue for the self-concept.

How far can the self be extended? Automatic attention capture is triggered not only by the self-face

The preferential processing of self-related information is thought to be driven by its high level of familiarity. However, some behavioral studies have shown that people may exhibit a preference for initially unfamiliar stimuli that have been associated with themselves arbitrarily. One of the key questions that needs to be addressed concerns the role of early attention in the prioritization of newly acquired information associated with the self. Another question is whether both highly familiar as well as new information referring to a subjectively significant person (i.e. close-other) benefits from preferential attentional processing. We aimed to tackle both questions by investigating the neural mechanisms involved in processing extremely familiar stimuli, like one's own face or the face of a close-other, as well as stimuli (abstract shapes) that were newly linked to each person. We used a dot-probe paradigm that allowed us to investigate the early stages of attentional prioritization. Our analysis of the N2pc component unveiled that attention was automatically captured by the self-face, a shape associated with oneself, and the face of the close person. However, a shape associated with the close-other did not elicit the same attentional response, as the N2pc was absent. Thus, both the self-face and information referring to the extended self (self-assigned shape, close-other's face) benefit from preferential early and automatic attentional processing.

Self-Prioritization Reconsidered: Scrutinizing Three Claims

Such is the power of self-relevance, it has been argued that even arbitrary stimuli (e.g., shapes, lines, colors) with no prior personal connection are privileged during information processing following their association with the self (i.e., self-prioritization). This prioritization effect, moreover, is deemed to be stimulus driven (i.e., automatic), grounded in perception, and supported by specialized processing operations. Here, however, we scrutinize these claims and challenge this viewpoint. Although self-relevance unquestionably influences information processing, we contend that, at least at present, there is limited evidence to suggest that the prioritization of arbitrary self-related stimuli is compulsory, penetrates perception, and is underpinned by activity in a dedicated neural network. Rather, self-prioritization appears to be a task-dependent product of ordinary cognitive processes.

Towards the self and away from the others: evidence for self-prioritization observed in an approach avoidance task

Processing advantages arising from self-association have been documented across various stimuli and paradigms. However, the implications of "self-association" for affective and social behavior have been scarcely investigated. The approach-avoidance task (AAT) offers an opportunity to investigate whether the privileged status of the "self" may also translate into differential evaluative attitudes toward the "self" in comparison to "others". In the current work, we first established shape-label associations using the associative-learning paradigm, and then asked the participants to engage in an approach-avoidance task to test whether attitudinal differences induced on the account of self-association lead to participants having different approach-avoidance tendencies toward the "self-related" stimuli relative to the "other-related" stimuli. We found that our participants responded with faster approach and slower avoidance tendencies for shapes associated with the "self" and slower approach and faster avoidance tendencies for the shapes associated with the "stranger." These results imply that "self-association" may lead to positive action tendencies toward "self-associated" stimuli, and at the same time lead to neutral or negative attitudes toward stimuli not related to the "self". Further, as the participants responded to self-associated vs. other-associated stimuli cohorts, these results may also have implications for the modulation of social group-behaviors in favor of those like the self and against those in contrast to the self-group.

EXPRESS: Self-Relevance and the Activation of Attentional Networks

Recent theoretical accounts maintain that core components of attentional functioning are preferentially tuned to self-relevant information. Evidence in support of this viewpoint is equivocal, however, with research overly reliant on personally significant (i.e., familiar) stimulus inputs (e.g., faces, forenames) and a diverse range of methodologies. Addressing these limitations, here we utilized arbitrary items (i.e., geometric shapes) and administered the Attention Network Test (ANT) to establish the extent to which self-relevance (vs. friend-relevance) moderates the three subsystems of attentional functioning - alerting, orienting, and executive control. The results revealed that only executive control was sensitive to the meaning of the stimuli, such that conflict resolution was enhanced following the presentation of self-associated compared to friend-associated shapes (i.e., cues). Probing the origin of this effect, a further computational analysis (i.e., Shrinking Spotlight Diffusion Model analysis) indicated that self-relevance facilitated the narrowing of visual attention. These findings highlight when and how the personal significance of otherwise trivial material modulates attentional processing.

Self-prioritization is supported by interactions between large-scale brain networks

Resting-state functional magnetic resonance imaging (fMRI) has provided solid evidence that the default-mode network (DMN) is implicated in self-referential processing. The functional connectivity of the DMN has also been observed in tasks where self-referential processing leads to self-prioritization (SPE) in perception and decision-making. However, we are less certain about whether (i) SPE solely depends on the interplay within parts of the DMN or is driven by multiple brain networks; and (ii) whether SPE is associated with a unique component of interconnected networks or can be explained by related effects such as emotion prioritization. We addressed these questions by identifying and comparing topological clusters of networks involved in self-and emotion prioritization effects generated in an associative-matching task. Using network-based statistics, we found that SPE controlled by emotion is supported by a unique component of interacting networks, including the medial prefrontal part of the DMN (MPFC), Frontoparietal network (FPN) and insular Salience network (SN). This component emerged as a result of a focal effect confined to few connections, indicating that interaction between DMN, FPC and SN is critical to cognitive operations for the SPE. This result was validated on a separate data set. In contrast, prioritization of happy emotion was associated with a component formed by interactions between the rostral prefrontal part of SN, posterior parietal part of FPN and the MPFC, while sad emotion reveals a cluster of the DMN, Dorsal Attention Network (DAN) and Visual Medial Network (VMN). We discussed theoretical and methodological aspects of these findings within the more general domain of social cognition.

Does Self-Associating a Geometric Shape Immediately Cause Attentional Prioritization?

In many cognitive tasks, stimuli associated with one's self elicit faster responses than stimuli associated with others. This is true for familiar self-representations (e.g., one's own name), for new self-associated stimuli, and for combinations of both. The current research disentangles the potential of self- versus stranger-representations for familiar, new, and paired (familiar + new) stimuli to guide attention. In Study 1 (N = 34), responses to familiar and new self- versus other representations were tested in a dot-probe task with a short stimulus-onset asynchrony (SOA; 100 ms). Study 2 (N = 31) and Study 3 (N = 35) use a long SOA (1,000 ms) to test whether the findings are mirrored in inhibition of return (IOR). We observe significant performance differences for targets following self- versus stranger-associated stimuli (i.e., a cuing effect or IOR depending on the SOA length), yet only when familiar representations are present. This indicates that, under conditions of attentional competition between self- and stranger-representations, familiar self-representations impact the distribution of attention while new self-representations alone do not.

Ventromedial Prefrontal Cortex Drives the Prioritization of Self-Associated Stimuli in Working Memory

Humans show a pervasive bias for processing self- over other-related information, including in working memory (WM), where people prioritize the maintenance of self- (over other-) associated cues. To elucidate the neural mechanisms underlying this self-bias, we paired a self- versus other-associated spatial WM task with fMRI and transcranial direct current stimulation (tDCS) of human participants of both sexes. Maintaining self- (over other-) associated cues resulted in enhanced activity in classic WM regions (frontoparietal cortex), and in superior multivoxel pattern decoding of the cue locations from visual cortex. Moreover, ventromedial PFC (VMPFC) displayed enhanced functional connectivity with WM regions during maintenance of self-associated cues, which predicted individuals' behavioral self-prioritization effects. In a follow-up tDCS experiment, we targeted VMPFC with excitatory (anodal), inhibitory (cathodal), or sham tDCS. Cathodal tDCS eliminated the self-prioritization effect. These findings provide strong converging evidence for a causal role of VMPFC in driving self-prioritization effects in WM and provide a unique window into the interaction between social, self-referential processing and high-level cognitive control processes.SIGNIFICANCE STATEMENT People have a strong tendency to attend to self-related stimuli, such as their names. This self-bias extends to the automatic prioritization of arbitrarily self-associated stimuli held in working memory. Since working memory is central to high-level cognition, this bias could influence how we make decisions. It is therefore important to understand the underlying brain mechanisms. Here, we used neuroimaging and noninvasive neurostimulation techniques to show that the source of self-bias in working memory is the ventromedial PFC, which modulates activity in frontoparietal brain regions to produce prioritized representations of self-associated stimuli in sensory cortex. This work thus reveals a brain circuit underlying the socially motivated (self-referential) biasing of high-level cognitive processing.

When self-prioritization crosses the senses: Crossmodal self-prioritization demonstrated between vision and touch

The investigation of self-prioritization via a simple matching paradigm represents a new way of enhancing our knowledge about the processing of self-relevant content and also increases our understanding of the self-concept itself. By associating formerly neutral material with the self, and assessing the resulting prioritization of these newly formed self-associations, conclusions can be drawn concerning the effects of self-relevance without the burden of highly overlearned materials such as one's own name. This approach was used to gain further insights into the structure and complexity of self-associations: a tactile pattern was associated with the self and thereafter, the prioritization of the exact same visual pattern was assessed - enabling the investigation of crossmodal self-associations. The results demonstrate a prioritization of self-associated material that rapidly extends beyond the borders of a sensory modality in which it was first established.