While Western psychology has typically operated under the "healthy normality" assumption which states that by their nature, humans are psychologically healthy, ACT assumes, rather, that psychological processes of a normal human mind are often destructive. The core conception of ACT is that psychological suffering is usually caused by experiential avoidance, cognitive entanglement, and resulting psychological rigidity that leads to a failure to take needed behavioral steps in accord with core values. As a simple way to summarize the model, ACT views the core of many problems to be due to the concepts represented in the acronym, FEAR: