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ruud_hortensius Researcher_In_Social_and_Affective_Neuroscience

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About my research

In my research I investigate the neural mechanisms of positive and negative social interactions, that is empathy and aggression. To that goal, I use neuroimaging, brain stimulation, behavioral measures, and virtual reality. Besides interactions between conspecifics, I also study how humans perceive and interact with artificial agents. Below you can find a description of past and present research projects (to be updated):

The bystander effect

A classical finding in social psychology tells us that helping behavior during an emergency is reduced in the presence of others (‘the bystander effect’). In this line of research, we take a novel approach and investigate the neural mechanisms underlying bystander apathy, the influence of personality characteristics, and use behavioral measures to predict helping behavior during a violent conflict. Based on the outcome of these studies we have begun to formulate a theoretical model that describes helping behavior in bystander situations as the net effect of two competing motivational processes.

Basolateral amygdala damaga and threat processing

The amygdala has long intrigued scientists. It is a region that plays a central role in social-emotional behavior. However, it is a heterogeneous structure consisting of different subnuclei with each having different roles. In this project, we investigated the impact of damage to the basolateral nucleus on threat processing. Using measures of functional activation and connectivity, we mapped the complex changes in the underlying neural architecture that give rise to the observed hypersensitivity for threat. 

Threat Reactivity

Detection and recognition are two parallel processes that drive the variety of responses to threatening situations. From freezing, to flight or fight. In a series of experiments, we investigated the independence of detection and recognition and the relation with awareness as reflected in measures of physiology, phenomenology, and behavior. Two separate but interrelated pathways allow for both detection-mediated automatic reactions independent of awareness and recognition-mediated deliberate reactions to threat.

The frontal cortex and aggression

When do people aggress and when do they ruminate after being insulted by another individual? In two experiments, we used transcranial direct current stimulation of the frontal cortex to influence these two seperate reactions after interpersonal provocation. When selectively shifting the balance between the left and right frontal cortex we were able to increase rumination and the coupling between anger and aggression.

Brain stimulation

My very first scientific endeavor involved transcranial magnetic stimulation interleaved with electroencephalography to study motor cortical excitability. After isolating the brain oscillations that influenced excitability levels, we used this information to selectively enhance excitability levels. In a separate study, we examined the basis of phosphenes induced by transcranial alternating current stimulation of the visual cortex and show that these phosphenes have a retinal and not a cortical origin.

Send me a mail


Contact me @ruudhortensius


Visit my Google Citations page


Visit the Social Brain in Action Lab and Social Robots website


Last update: August 20 2017


*The Bangor Social Robotics Workshop on the Emerging Social Neuroscience of Human-Robot Interaction that Emily Cross and I organized took place on the 17th and 18th of August!  A short summary can be found here.


*Two cultures merge! We received a ESRC Impact Acceleration Award for an artist-in-residency. Artist Merel Bekking will collaborate with Emily Cross and me on an art installation involving robots! More info soon!


*A very first preprint! Felix Hekele, Emily Cross and I wrote a review on the perception and reaction to emotions expressed by artificial agents. Read it at PsychArXiv


*My research on the bystander effect was features in an article in Psychologie Magazine.