Case 4 Origins of aggression: nature
1. Which hormones play a role in aggression?
- Norepinephrine
- High testosterone levels
- Diminished serotonin functioning (lower serotonin levels->high aggression)
- Individual fluctuations in testosterone important for aggression. No clear association
testosterone and aggression.
2. Which brain parts are involved in aggression and what is their function and also are
they overactive or underactive?
Article Engelhardt
- Previous research has shown that media violence exposure can cause desensitization to
violence, which in theory can increase aggression. However, no study to date has
demonstrated this association. In the present experiment, participants played a violent
or nonviolent video game, viewed violent and nonviolent photos while their brain
activity was measured, and then gave an ostensible opponent unpleasant noise blasts.
Participants low in previous exposure to video game violence who played a violent
(relative to a nonviolent) game showed a reduction in the P3 component of the event-
related brain potential (ERP) to violent images (indicating physiological
desensitization), and this brain response mediated the effect of video game content on
subsequent aggressive behavior. These data provide the first experimental evidence
linking violence desensitization with increased aggression, and show that a neural
marker of this process can at least partially account for the causal link between violent
game exposure and aggression.
- Desensitization theory proposes that repeated exposure to violence results in
habituation of the initially negative cognitive, emotional, and physiological responses
people experience when they see blood and gore. This theory is supported by research
showing that violent media exposure is associated with decreased cardiovascular,
electrodermal, neural, and empathic responses during depictions of real violence.
- Desensitization to violent media, in turn, has been theoretically linked to increases in
aggressive behavior. Habitual exposure to violent media may reduce aggressive
inhibitions and empathy for the pain and suffering of others, and weaken typical
aversions to violence, all of which should increase the likelihood of aggressive
responses.
- In the present experiment, participants varying in levels of previous violent video
game exposure played either a violent or nonviolent video game in the lab. Acute
desensitization following game play was determined using the amplitude of the P300
(P3) component of the event-related brain potential (ERP) elicited by photos depicting
real violence, and aggression was measured via levels of unpleasant noise blasts
participants gave an ostensible opponent.
- we predicted that participants randomly assigned to play a violent video game would
show smaller P3 amplitudes to violent images compared to participants assigned to
play a nonviolent game. we also predicted that participants who play a violent (relative
to a nonviolent) game would subsequently behave more aggressively. Finally, we
predicted that the P3 elicited by violent pictures would negatively predict aggressive
behavior, and would mediate the relationship between violent game exposure and
aggressive behavior.
1
, - participants who played a violent game were more aggressive than those who played a
nonviolent game. This effect was similar in magnitude for participants low and high in
previous violent video game exposure. Violent images elicited smaller P3s among
participants high in previous violent video game exposure than among those low in
previous exposure. Follow-up contrasts showed that participants low in previous
violent game exposure who played a violent game in the lab had smaller P3
amplitudes to violent images than did their peers who played a nonviolent game.
Participants high in previous violent game exposure had small P3 amplitudes to
violent images regardless of whether they played a violent or nonviolent game in the
lab. the P3 elicited by violent images negatively predicted aggression (i.e., smaller P3s
predicted more aggression). at least for individuals whose prior exposure to video
game violence was low, playing a violent video game caused a reduction in the brain's
response to depictions of real-life violence, and this reduction, in turn, predicted an
increase in aggression.
- The fact that video game exposure did not affect the P3 amplitudes of high-exposure
participants is interesting, and suggests a number of possibilities. First, it could be that
these individuals are already so desensitized that an acute exposure to violent media
was insufficient to bring about further changes in their neural responses to violence.
Second, it could be that some unmeasured factor causes both an affinity for violent
media and a reduced P3 response to violent imagery in violent gamers. In either case,
the fact that playing a violent video game increased aggression for both low- and high-
exposure participants, but the P3 response to violence was reduced for high-exposure
participants regardless of the game they played, suggests that additional mechanisms
not measured here are important to consider.
3. Is there evidence that non-invasive brain stimulation effects aggression?
Article Dambacher
- neural networks associated with aggression included various regions within prefrontal
cortex, the insular cortex, the cingulate cortex, striatal areas and the amygdala. anger-
related (thus approach-related) brain states have also been allocated to the left
prefrontal cortex.
- Non-invasive brain stimulation methods such as
Transcranial Magnetic Brain Stimulation (TMS) or
transcranial Direct Current Stimulation (tDCS) are
mechanistic or causal techniques that are able to further
clarify the role of the prefrontal cortex in mediating
aggressive behavior. While TMS can enhance or disturb
brain activity in a specific region by means of
electromagnetic induction, tDCS induces low electric
currents into brain tissue to either decrease or increase the
excitability of the stimulated areas.
- One of the cognitive mechanisms playing a role in
aggressive behavior is the processing of social cues such
as, for instance, social situation, social counterpart or
social content of communication. Social cue processing is biased in aggressive
individuals. reactive and
- proactive aggression revert to biases in different stages of social information
processing. Thereby, reactive aggression seems to result from deviations in rather
2
1. Which hormones play a role in aggression?
- Norepinephrine
- High testosterone levels
- Diminished serotonin functioning (lower serotonin levels->high aggression)
- Individual fluctuations in testosterone important for aggression. No clear association
testosterone and aggression.
2. Which brain parts are involved in aggression and what is their function and also are
they overactive or underactive?
Article Engelhardt
- Previous research has shown that media violence exposure can cause desensitization to
violence, which in theory can increase aggression. However, no study to date has
demonstrated this association. In the present experiment, participants played a violent
or nonviolent video game, viewed violent and nonviolent photos while their brain
activity was measured, and then gave an ostensible opponent unpleasant noise blasts.
Participants low in previous exposure to video game violence who played a violent
(relative to a nonviolent) game showed a reduction in the P3 component of the event-
related brain potential (ERP) to violent images (indicating physiological
desensitization), and this brain response mediated the effect of video game content on
subsequent aggressive behavior. These data provide the first experimental evidence
linking violence desensitization with increased aggression, and show that a neural
marker of this process can at least partially account for the causal link between violent
game exposure and aggression.
- Desensitization theory proposes that repeated exposure to violence results in
habituation of the initially negative cognitive, emotional, and physiological responses
people experience when they see blood and gore. This theory is supported by research
showing that violent media exposure is associated with decreased cardiovascular,
electrodermal, neural, and empathic responses during depictions of real violence.
- Desensitization to violent media, in turn, has been theoretically linked to increases in
aggressive behavior. Habitual exposure to violent media may reduce aggressive
inhibitions and empathy for the pain and suffering of others, and weaken typical
aversions to violence, all of which should increase the likelihood of aggressive
responses.
- In the present experiment, participants varying in levels of previous violent video
game exposure played either a violent or nonviolent video game in the lab. Acute
desensitization following game play was determined using the amplitude of the P300
(P3) component of the event-related brain potential (ERP) elicited by photos depicting
real violence, and aggression was measured via levels of unpleasant noise blasts
participants gave an ostensible opponent.
- we predicted that participants randomly assigned to play a violent video game would
show smaller P3 amplitudes to violent images compared to participants assigned to
play a nonviolent game. we also predicted that participants who play a violent (relative
to a nonviolent) game would subsequently behave more aggressively. Finally, we
predicted that the P3 elicited by violent pictures would negatively predict aggressive
behavior, and would mediate the relationship between violent game exposure and
aggressive behavior.
1
, - participants who played a violent game were more aggressive than those who played a
nonviolent game. This effect was similar in magnitude for participants low and high in
previous violent video game exposure. Violent images elicited smaller P3s among
participants high in previous violent video game exposure than among those low in
previous exposure. Follow-up contrasts showed that participants low in previous
violent game exposure who played a violent game in the lab had smaller P3
amplitudes to violent images than did their peers who played a nonviolent game.
Participants high in previous violent game exposure had small P3 amplitudes to
violent images regardless of whether they played a violent or nonviolent game in the
lab. the P3 elicited by violent images negatively predicted aggression (i.e., smaller P3s
predicted more aggression). at least for individuals whose prior exposure to video
game violence was low, playing a violent video game caused a reduction in the brain's
response to depictions of real-life violence, and this reduction, in turn, predicted an
increase in aggression.
- The fact that video game exposure did not affect the P3 amplitudes of high-exposure
participants is interesting, and suggests a number of possibilities. First, it could be that
these individuals are already so desensitized that an acute exposure to violent media
was insufficient to bring about further changes in their neural responses to violence.
Second, it could be that some unmeasured factor causes both an affinity for violent
media and a reduced P3 response to violent imagery in violent gamers. In either case,
the fact that playing a violent video game increased aggression for both low- and high-
exposure participants, but the P3 response to violence was reduced for high-exposure
participants regardless of the game they played, suggests that additional mechanisms
not measured here are important to consider.
3. Is there evidence that non-invasive brain stimulation effects aggression?
Article Dambacher
- neural networks associated with aggression included various regions within prefrontal
cortex, the insular cortex, the cingulate cortex, striatal areas and the amygdala. anger-
related (thus approach-related) brain states have also been allocated to the left
prefrontal cortex.
- Non-invasive brain stimulation methods such as
Transcranial Magnetic Brain Stimulation (TMS) or
transcranial Direct Current Stimulation (tDCS) are
mechanistic or causal techniques that are able to further
clarify the role of the prefrontal cortex in mediating
aggressive behavior. While TMS can enhance or disturb
brain activity in a specific region by means of
electromagnetic induction, tDCS induces low electric
currents into brain tissue to either decrease or increase the
excitability of the stimulated areas.
- One of the cognitive mechanisms playing a role in
aggressive behavior is the processing of social cues such
as, for instance, social situation, social counterpart or
social content of communication. Social cue processing is biased in aggressive
individuals. reactive and
- proactive aggression revert to biases in different stages of social information
processing. Thereby, reactive aggression seems to result from deviations in rather
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