Why being ignored is 'painful' for human beings? Ignoring someone is a manipulatory technique used at times. Ignoring the attacks of someone else through emotional detachment has a very strong effect on the attacker.

Is there a name for this kind of manipulative behavior?
Ignoring is a type of social rejection see extracts from wiki:

Social rejection occurs when an individual is deliberately excluded
from a social relationship or social interaction. ... rejection can be either active, by bullying, teasing, or ridiculing, or passive, by ignoring a person, or giving the &quot;silent treatment.&quot;
...
Researchers have also investigated how the brain responds to social
rejection. One study found that the dorsal anterior cingulate cortex
is active when people are experiencing both physical pain and &quot;social
pain,&quot; in response to social rejection.