According to The Free Dictionary:
1. To render insensitive or less sensitive.
2. Immunology To make (an individual) nonreactive or insensitive to an antigen.
3. To make emotionally insensitive or unresponsive, as by long exposure or repeated shocks: “This movie in effect may resensitize people who thought they were desensitized to violence” (Steven Spielberg).
4. To make (a photographic film or substance) less sensitive to light.
Examples would be:
Deliberate desensitization for the treatment of phobiasWhen you confront your cadaver during the first week of school, you will begin to learn emotional aloofness. Prospective doctors become desensitized to death’s symbols -bones, blood, corpses, and stench- symbols that disturb most people. Some students become desensitized earlier during premed courses that required them to dissect or even kill living things. In any event, this phase of medical school can still be disturbing. A psychiatrist who interviewed students found that many of them had nightmares about their anatomy experiences.
No matter how great the initial shock, however, it apparently wears off for most students. Before long you become so desensitized that you can eat lunch around the corpse.
Surviving Medical School by Robert H. Coombs (page 137-138)
And now the repeated exposure is also being done virtually:Repeated exposure to the feared object or situation desensitizes the patient to the point where they lose their phobia (or it is greatly reduced).
In psychology, desensitization (also called inurement) is a process for mitigating the harmful effects of phobias or other disorders. It also occurs when an emotional response is repeatedly evoked in situations in which the action tendency that is associated with the emotion proves irrelevant or unnecessary. Agoraphobics, who fear open spaces and social gatherings outside their own home, may be gradually led to increase their interaction with the outside world by putting them in situations that are uncomfortable but not panic-provoking for them. Mastering their anxiety in very small doses can allow them to take greater steps to self-reliance. Desensitization can be an alternative or a supplement to anxiety-reducing medication.
http://en.wikipedia.org/wiki/Desensitiz ... chology%29
Virtual Reality & Cockroaches
Over-exposure to video pornography can also desensitization the viewer to point where the viewer loses sexual responsiveness.
http://www.psychologytoday.com/blog/cup ... ysfunction
http://www.psychologytoday.com/blog/cup ... -goes-down
http://www.psychologytoday.com/blog/cup ... oned-arrow
Update: Study finds that violent video games help to desensitize soldiers to violence, making them less bothered by real-world violence.
http://www.newscientist.com/blogs/onepe ... htmar.html