The psychological roots of terrorist actions can be difficult to pin down. Extremist thinking is "rigid, primitive, and unsophisticated" and their emotional state best described as "impassioned filled with disappointment, frustration, fear, disgust, anger, and hatred," finds an article published in 2007 in the journal Aggression and Violent Behavior.
The author cited a variety of factors for these cognitive and psychological states, ranging from a poor education system marked by memorization, a personal life scarred by failure (to hold a job, to marry, to adjust to modernity, etc.), or dissatisfaction with a combination of "social, economic, political cultural, or religious conditions."
No study of the terrorist's mindset could ever completely explain their behavior. But the closer psychologists and policymakers get to understanding extremist psychological and cognitive patterns, the better equipped security and officials will be to deal with terrorists.