Neural Correlates of Hate: A Neurobiological Perspective
Hate, often seen as a destructive emotion, has been the subject of scientific investigation to understand its neural underpinnings. A study by Professor Semir Zeki and John Romaya at the Wellcome Laboratory of Neurobiology at UCL delved into the brain areas associated with hate, revealing a 'hate circuit' distinct from those related to fear, threat, and danger, yet sharing a connection with aggression.
Brain regions such as the medial frontal gyrus, putamen, premotor cortex, frontal pole, and insula are activated when viewing a hated face.
These findings are an extension of previous research from the same laboratory on the brain mechanisms of romantic and maternal love. Professor Zeki explains, "Hate is often considered to be an evil passion that should, in a better world, be tamed, controlled, and eradicated. Yet to the biologist, hate is a passion that is of equal interest to love. Like love, it is often seemingly irrational and can lead individuals to heroic and evil deeds."
Methodology and Findings
To compare the results with previous findings on romantic love, Zeki and Romaya specifically studied hate directed against an individual. Seventeen subjects, both female and male, had their brains scanned while viewing pictures of their hated person as well as that of neutral faces with which they were familiar.
The 'hate circuit' includes structures in the cortex and sub-cortex, with components crucial for generating aggressive behavior and translating it into action through motor planning. The subcortical activity involves two distinct structures: the putamen and insula.
Professor Zeki added: "Significantly, the putamen and insula are also both activated by romantic love. This is not surprising." The putamen could be involved in preparing aggressive acts in a romantic context, such as when a rival presents a danger.
The insula is involved in both hate and romantic love.
Cortical Activity and Intensity of Hate
A marked difference in the cortical pattern produced by love and hate is that, whereas with love large parts of the cerebral cortex associated with judgment and reasoning become de-activated, with hate only a small zone, located in the frontal cortex, becomes de-activated.
Interestingly, the activity in some of these structures in response to viewing a hated face is proportional in strength to the declared intensity of hate, thus allowing the subjective state of hate to be objectively quantified.
Unlike romantic love, which is directed at one person, hate can be directed against entire individuals or groups, as is the case with racial, political, or gender hatred. The study thus shows that there is a unique pattern of activity in the brain in the context of hate.
In a block-design fMRI study, 17 normal human subjects were scanned while viewing the face of a person they hated and also faces of acquaintances for whom they had neutral feelings. A hate score was obtained for the object of hate for each subject and this was used as a covariate in a between-subject random effects analysis.
Viewing a hated face resulted in increased activity in the medial frontal gyrus, right putamen, bilaterally in premotor cortex, in the frontal pole and bilaterally in the medial insula. Also, three areas were found where activation correlated linearly with the declared level of hatred: the right insula, right premotor cortex, and the right fronto-medial gyrus. One area of deactivation was found in the right superior frontal gyrus.
Summary of Brain Activity During Hate
The study identifies specific brain regions that exhibit increased activity when a person views the face of someone they hate. These areas include:
- Medial Frontal Gyrus: Involved in cognitive functions and emotional regulation.
- Right Putamen: Associated with motor control and learning.
- Premotor Cortex: Plays a role in planning and executing movements.
- Frontal Pole: Involved in higher-order cognitive processes.
- Medial Insula: Related to emotional awareness and interoception.
Additionally, the intensity of activation in the right insula, right premotor cortex, and right fronto-medial gyrus correlated with the declared level of hatred. This suggests that these regions are directly involved in processing the subjective experience of hate.
Brain activity during viewing a hated face.
Quantifying Hate: Linking Subjective Experience to Brain Activity
One of the most intriguing findings of the study is the correlation between the declared intensity of hate and the activity in specific brain structures. This suggests that the subjective experience of hate can be objectively quantified by measuring the activity in these regions.
This finding opens up new possibilities for understanding the neural mechanisms underlying hate and for developing interventions to reduce its impact.
Figures from the Study
The images used in the study were converted to grayscale and normalized with respect to visual area and average brightness. They were roughly matched in terms of spatial frequency and intensity contrast. The faces were all of the same sex, the expressions were similar, and a vertically aligned full-face image was selected in each case. An individual set of four such faces was presented to each subject.
A search volume of 5,225 voxels was defined using the t-statistic for the effect Hated face>Neutral faces with the statistical threshold set at p≤0.01 (uncorrected). Within this search volume voxels were identified where the effect Hated face>Neutral faces covaried with the hate questionnaire score. The voxel-level statistical threshold was set at p≤0.05, family-wise corrected for multiple comparisons within the search volume.
References
- Bartels A, Zeki S. The neural basis of romantic love. Neuroreport.
- Bartels A, Zeki S. The neural correlates of maternal and romantic love. Neuroimage.
- Hatfield E, Sprecher S. Measuring passionate love in intimate relations. J Adolescence.
- Sternberg RJ. Understanding and Combating Hate. In: Sternberg RJ, editor. The Psychology of Hate. American Psychological Association; 2004.
- Kawabata H, Zeki S. Neural correlates of beauty. J Neurophysiol.