Terrorism clearly draws attention to the group that perpetuated the crime in the media although it is not clear that it 'works' to achieve the stated goals of the groups that use it. Studies of the efficacy of terrorism indicate that it often backfires, at least violent terrorism. "When terrorists kill civilians or captives, it significantly lowers the likelihood of bargaining success" (Solomon 2013). However, some might argue that the accomplishments of former terrorist organizations in gaining the ability to negotiate with the offending power such as the Irish Republican Army (IRA) and the Palestinian Liberation Organization (PLO) (both of which have long renounced terrorism but which began as paramilitary groups) might suggest that violence is often useful in achieving group objectives (Solomon 2013).
But in these instances, the goals of the groups were relatively concrete (expelling British and Israeli influence, respectively, from contested territories). Other groups, such as Al-Qaida, seem to have a more diffuse goal of merely waging a cultural war against the West that is impossible to say that one has 'won.' Also, "Islamic terrorists often make what seem to outsiders as unrealistic demands because the terrorists see them as sacred, but are able to claim victory if they are even partially met," which means that even what seems like a failure in the eyes of the West is a victory to the terrorist -- simply the ability to do violence and gain attention is 'victory' enough even if the terrorists claim that their ultimate goal is the eradication of secular Western civilization (Solomon 2013).
But there is no denying that "terrorism has succeeded at times in killing policies. A suicide bombing -- one of the first -- that killed 241 U.S. Marines and other U.S. other military service members in Beirut in 1983 destroyed American policy of helping to create a stable government in Lebanon. America withdrew a few months after the attack" (Jenkins 2004). Also, although some governments such as the United States refuse to negotiate with terrorists, other governments will do so to win back hostages in a continuing conflict such as Israel. Thus, at least in terms of achieving short-term goals, terrorism can actually yield dividends to a radical group.
Jenkins, B. (2004). Does terrorism work? The Rand Corporation. Retrieved from:
One common theory as to why people join terrorist groups is the concept of unmet expectations. "Concrete grievances among an identifiable subgroup lead to the development of a social movement aimed at redressing grievances real or perceived. These feelings of discrimination or deprivation must be viewed as unjust and underserved…if terrorists perceive the state as unjust, morally corrupt, or violent, then terrorism [as revenge] may seem legitimate and justified" (Moscoe 2013:1). A good example of this is the IRA in Great Britain, which it believed would not concede to its demands without the pressures of violence, or the PLO which viewed Israel's presence in the West Bank and Gaza Strip to be illegitimate forms of control (Moscoe 2013:1).
However, there may also be psychological components of a desire to affiliate one's self with a terrorist group, such as a desire for a sense of belonging. Economic dissatisfaction is often said to motivate violence, although it should be noted that not all notable terrorists have originated from disaffected groups (some of the leadership of Al-Qaida, including Bin Laden, was quite well-educated). A sense of isolation and a separation between one's self and a hostile world has found to be the most significant psychological component of the terrorist psychology, a "lethal combination of isolation and internal consensus, such that patterns of mutual reassurance, solidarity, and comradeship reinforce beliefs about a hostile outside world" (Moscoe 2013: 7). Discrimination by hegemonic groups can sharpen this sense.
The psychology of becoming part of the terrorist group can reinforce this 'us vs. them' philosophy and also motivate individuals who might not perpetuate crimes against the state alone to act violently. The group provides both solidarity and an all-encompassing worldview that shuts down the possibility of dissent. As the group grows more violent, this psychology can actually be reinforced: "If terrorists commit an attack and a state uses extreme force to send a punishing message back, the terrorists may use that action…