Attachment in adults is commonly measured using the Adult Attachment Interview, the Adult Attachment Projective Picture System, and self-report questionnaires. Self-report questionnaires assess attachment style, a personality dimension that describes attitudes about relationships with romantic partners. Adult attachment style is thought to be similar to childhood attachment patterns. There is some research that shows a link between childhood attachment patterns and attachment personality dimensions with romantic partners, but correlations are mild to moderate. The most common approach to defining attachment style is a two-dimension approach in defining attachment style. One dimension deals with anxiety about the relationship, and the other dimension dealing with avoidance in the relationship. Another approach defines four adult attachment style categories: secure, preoccupied, dismissive-avoidant, and fearful-avoidant.