Cardiac afferent activity modulates the expression of racial stereotypes

Abstract

Negative racial stereotypes tend to associate Black people with threat. This often leads to the misidentification of harmless objects as weapons held by a Black individual. Yet, little is known about how bodily states impact the expression of racial stereotyping. By tapping into the phasic activation of arterial baroreceptors, known to be associated with changes in the neural processing of fearful stimuli, we show activation of race-threat stereotypes synchronized with the cardiovascular cycle. Across two established tasks, stimuli depicting Black or White individuals were presented to coincide with either the cardiac systole or diastole. Results show increased race-driven misidentification of weapons during systole, when baroreceptor afferent firing is maximal, relative to diastole. Importantly, a third study examining the positive Black-athletic stereotypical association fails to demonstrate similar modulations by cardiac cycle. We identify a body-brain interaction wherein interoceptive cues can modulate threat appraisal and racially biased behaviour in context-dependent ways.

Figure 1. Study 1.

(a) Graphical representation of the experimental procedure. In this adaptation of the WIT, participants (n=30) had to discriminate between pictures (targets) of tools and weapons that were preceded by pictures (primes) of a White or a Black male face. Prime onset was synchronized with different phases of the cardiac cycle—systole or diastole—to investigate the modulatory role of cardiac afferent signalling on the expression of this stereotype. (b) Cumulative frequencies of stimuli onset (ms) relative to the R-wave peak for each cardiac cycle condition. Trials were then re-coded a-posteriori according to their onset time—stimuli presented between 200–400 ms were defined as systole and those between 450–800 ms defined as diastole. Excluded time intervals are displayed in faded colour. (c) Average accuracy rates (and standard errors) as a function of object type, prime and cardiac cycle. Results reveal that participants showed a relative enhancement of racial bias when primes were presented during the period of maximal baroreceptor activity (at systole) compared with reduced bias when it was minimal (at diastole).

Figure 2. Study 2.

(a) Graphical representation of the experimental procedure. In this adapted version of the FPST, participants (n=30) were presented for a brief period (200 ms) with pictures of a White or Black male holding either a weapon or a harmless object (for example, phone, wallet) in his hand, and had to make the split-second decision of whether to ‘shoot' or ‘don't shoot' him, respectively. Crucially, we time-locked the presentation of the target to coincide either with the cardiac systole or the cardiac diastole. (b) Cumulative frequencies of stimuli onset (ms) relative to the R-wave peak for each cardiac cycle condition. Trials were then re-coded a-posteriori according to their onset time—stimuli presented between 200–400 ms were defined as systole and those between 450–800 ms defined as diastole. Excluded time intervals are displayed in faded colour. (c) Average accuracy rates (and s.e.) as a function of object type, race and cardiac cycle. Participants were more likely to ‘shoot' unarmed Black than unarmed White individuals when stimuli was perceived during systole compared to when perceived during diastole. For publication purposes, the images were blurred around the targets' faces to conceal the models' identity.

Figure 3. Study 3.

(a) Graphical representation of the experimental procedure. The sport-fruit identification task (SFIT) is a modified version of the experimental paradigm used in Study 1 in which participants (n=30) need to discriminate between pictures (targets) of fruits and sport-objects that are preceded by pictures (primes) of a White or a Black male face. As in Study 1, we synchronized prime onset to coincide with the cardiac systole or diastole. (b) Cumulative frequencies of stimuli onset (ms) relative to the R-wave peak for each cardiac cycle condition. Trials were then re-coded a-posteriori according to their onset time—stimuli presented between 200–400 ms were defined as systole and those between 450–800 ms defined as diastole. Excluded time intervals are displayed in lighter shades. (c) Average accuracy rates (and standard errors) as a function of object type, race and cardiac cycle. Primes successfully induced response bias as reflected by the prime × object interaction. In particular, we observed greater accuracy in the identification of sport-objects preceded by Black (versus White) faces and improved identification of fruits preceded by White (versus Black) faces. However, in contrast with Study 1, this effect was not modulated by cardiac cycle. Together with the results from Study 1, Study 3 shows that cardiac cycle effects in the processing of racial cues are context dependent, such that the salient negative association Black-threat, but not the positive Black-athletic stereotype, is modulated by baroreceptor-mediated effects of interoceptive feedback.