A new study published in Social Neuroscience explored how the human brain processes faces of political leaders, testing whether partisanship influences these early neural responses. Using electroencephalography (EEG), researchers found that people tend to show stronger brain activity when viewing politicians’ faces compared to strangers. However, they did not observe differences in neural responses based on whether the politician aligned with or opposed the viewer’s political affiliation. These findings indicate that while politicians’ faces appear to command more attention, early neural signals may not yet reflect partisan bias.
Partisan identity has been tied to biased reasoning, altered memory, and emotional reactions to political opponents. Yet much of this evidence comes from surveys or behavioral tasks, leaving open the question of whether such bias is also reflected in the earliest stages of perception. Previous research in social neuroscience has shown that social categories like race can influence the brain’s early responses to faces. The current study aimed to extend this work to the political domain by testing whether partisanship shapes the way the brain initially processes politicians’ faces.
“We were intrigued by the question of how deeply partisanship shapes our perception, especially at the neural level. Prior research shows partisanship can distort memory and reasoning, but much of that work is based on self-report or behavioral tasks. We wanted to go a step further and see whether partisan biases appear in the brain within milliseconds of seeing a politician’s face, before a person has time to consciously reflect,” said study author Gustavo Couto de Jesus of the University of Amsterdam.
“Faces are powerful stimuli for studying bias and social identity. They’re rich with emotional and social information, and we naturally use them to quickly assess traits like trustworthiness, competence, and group membership. Prior research even shows that the way we process faces can reflect out-group categorization and dehumanization. That makes them ideal for probing the subtle, often unconscious ways we respond to political leaders.”
“To explore this, we used event-related potentials (ERPs), a method that tracks electroencephalographic (EEG) brain activity with millisecond precision, and combined it with a face-viewing task,” Couto de Jesus explained. “We began by conducting a review of previous ERP research in areas such as race and minimal group bias, where early neural differences have been consistently observed in response to in-group and out-group faces.”
“Based on this literature, we expected to find similar early effects when participants viewed in-party versus out-party political leaders, particularly in components like the P200 and N200. The P200 is linked to rapid, automatic attention to salient or potentially threatening stimuli, activated by the out-group, while the N200 is associated with conflict detection and cognitive control, activated by the in-group. Our goal was to determine whether political identity, like other social groupings, influences attentional processes in the earliest stages of face perception.”
The experiment took place in the Netherlands, a country with a multi-party system, allowing researchers to examine partisan effects in a more diverse political context. The study included 51 adult participants, most of them university students, who were asked to identify both their preferred political parties (in-parties) and those they strongly opposed (out-parties).
Participants viewed a series of video clips showing Dutch political leaders and unfamiliar individuals. Each video began with a static neutral facial expression, transitioned into a dynamic emotional expression, and ended with a second static image. For the purposes of the EEG analysis, only the first 800 milliseconds of the neutral face display were analyzed. During this interval, EEG was used to record participants’ brain responses to the different faces.
To measure the strength of participants’ political identification, the researchers used “feeling thermometers,” asking people to rate how warmly they felt toward the political parties in question. Stronger identification was expected to predict greater neural differentiation between in-party and out-party leaders.
The most consistent finding was that the N170 component — a negative deflection in brain activity about 170 milliseconds after seeing a face — was significantly stronger when participants viewed politicians compared to unfamiliar individuals. This suggests that politicians’ faces tend to grab more early-stage visual attention, potentially due to their familiarity or emotional salience. The effect was small but statistically reliable and was also supported by a data-driven analysis looking across the whole brain.
In contrast, the study found no such pattern for the N250 component, which is often thought to reflect facial familiarity. Participants’ brains did not respond differently to politicians and strangers in this time window. This suggests that while politicians’ faces may draw attention, they might not be processed as more personally familiar than strangers’ faces — at least not in the way that would elicit a classic familiarity signal.
The researchers also looked for differences in brain activity when comparing in-party and out-party political leaders, focusing on the P200 and N200 components. These ERP signals have been linked to attentional biases toward in-group or out-group members in studies of race and social categorization. But in this study, no significant differences emerged between in-party and out-party conditions, even when accounting for individual differences in partisanship strength.
“Based on previous research in social neuroscience, particularly studies involving race and minimal group paradigms, we expected to observe early neural differences between in-party and out-party politicians, especially in components like the P200 and N200 that emerge before 350 milliseconds,” Couto de Jesus told PsyPost. “The absence of such effects in our study suggests that partisanship may not operate like other social categories at these initial stages of perceptual processing.”
“We also examined neural responses up to 800 milliseconds after stimulus onset and still found no evidence of differentiation based on party alignment, suggesting that even later, more evaluative stages of processing were not engaged. One possibility is that political group membership, unlike more visually or evolutionarily salient social cues, does not trigger automatic bias in the absence of additional context or task relevance. This points to the idea that partisan identity may be more cognitively mediated, requiring semantic or situational cues to influence neural processing, particularly when individuals are simply viewing faces without being asked to evaluate or react to them.”
The findings from this study indicate that while the human brain tends to give special attention to the faces of political leaders, early neural responses do not appear to reflect partisan bias.
“We found that politicians’ faces, in general, elicit stronger early neural responses (specifically in the N170 component) than unfamiliar faces, suggesting that political figures are attentionally salient,” Couto de Jesus summarized. “However, we did not find evidence that this early processing differs based on whether the politician belongs to someone’s preferred (in-party) or opposing (out-party) group.”
“In short: political faces grab our brain’s attention early, but partisan bias doesn’t seem to kick in at that stage. These findings suggest that early perceptual processing prioritizes political figures based on their social relevance, but evaluative biases such as those shaped by partisanship may require additional context or meaning to be activated, or simply emerge later.”
The authors caution that their findings may reflect the specific context of the Netherlands, where political polarization is generally lower than in countries like the United States. In such an environment, partisan identities may be less automatically activated, reducing the likelihood of early neural differentiation. More polarized societies might show stronger effects.
Additionally, the study examined only the earliest stages of brain activity. It’s possible that partisan bias emerges at later processing stages — during evaluation, interpretation, or memory — rather than during initial visual perception. Functional brain imaging (fMRI), for instance, might detect longer-lasting effects that occur after more cognitive elaboration.
“Our findings don’t imply that partisanship has no influence on perception — it clearly does, especially when it comes to how people interpret, evaluate, and respond to political information,” Couto de Jesus said. “However, this study suggests that the mere sight of a political leader’s face, presented without any additional message, task, or context, may not be sufficient to trigger partisan bias in the brain’s early stages of processing. This is especially notable given the complexity of our research setting: we conducted the study in the Netherlands, a multiparty system where political allegiances are more fragmented than in two-party systems.”
“Additionally, the politicians we included, two from the participant’s in-party and two from an out-party, may inevitably vary in public familiarity and personal resonance. It’s also important to acknowledge that EEG and ERPs primarily measure cortical activity at the surface of the brain and may not fully capture deeper neural processes, such as those occurring in the amygdala or other subcortical structures involved in emotional processing. If a neural process is too weak and too ‘hidden,’ it can be obfuscated by other more prominent neural processes.”
Future research could also explore how different cues interact with visual processing. They also call for cross-cultural studies comparing countries with different political climates.
“We’d like to explore what kinds of contexts or cues are necessary to activate partisan bias in the brain,” Couto de Jesus explained. “Does it emerge only when we hear a politician speak, when we observe an emotional expression, or when we’re placed in a situation that demands a judgment or decision? One important next step is to examine how visual cues like a politician’s face interact with other types of political information, such as explicit party labels, ideological statements, or emotionally charged messages. Combining these elements could help us better understand how and when motivated reasoning kicks in, as individuals begin to selectively attend to, interpret, and evaluate information through a partisan lens.”
“We’re also interested in whether these dynamics differ across political environments. In more polarized settings, like the United States, partisan identities may be more chronically activated and more likely to produce early neural differentiation.”
“More broadly, we see political information processing as a series of stages, beginning with basic perception, moving through affective and evaluative responses, and ultimately influencing reasoning and decision-making,” Couto de Jesus continued. “Our aim is to examine how each of these stages builds on the one before, and whether early neural responses can predict later biased interpretations or behaviors. By understanding where in this pipeline partisanship begins to exert its influence, we can better grasp the conditions under which political biases are triggered, amplified, or possibly even resisted.”
The findings (or lack thereof) adds a layer of complexity to the understanding of political cognition. They indicate that while political attitudes can influence how people interpret and evaluate information, they may not automatically alter the brain’s earliest perceptual responses. In some contexts, basic visual processing appears to operate independently of partisan bias.
“The study highlights the importance of not over-attributing bias to every cognitive process,” Couto de Jesus explained. “While partisanship clearly shapes how people interpret and respond to political information, our findings suggest that early visual perception and attention, such as seeing a politician’s face without added context, may engage more face-specific attributes or focus on the general politician category.”
“It is also important to acknowledge that how faces are processed can vary widely depending on the design and stimuli. Visually salient group cues may trigger earlier attentional responses than first recalling an individual and then categorizing their partisan identity. To better understand what ERP components like the N170, P200, or N200 reflect in political perception, we need more cross-contextual research. This means using more diverse samples, comparing across political systems, and incorporating richer stimuli that better reflect real-world political experiences. This will help clarify what these neural markers capture and when partisan bias truly begins to shape perception.”
The study, “An ERP-study on the extent to which partisanship conditions the early processing of politicians’ faces,” was authored by Gustavo Couto de Jesus, Maaike D. Homan, Diamantis Petropoulos Petalas, Bert N. Bakker, Joe Bathelt, and Gijs Schumacher.
