Experiential avoidance (EA) has been broadly defined as attempts to avoid thoughts, feelings, memories, physical sensations, and other internal experiences — even when doing so creates harm in the long run. The process of EA is thought to be maintained through negative reinforcement — that is, short-term relief of discomfort is achieved through avoidance, thereby increasing the likelihood that the avoidance behavior will persist.  Importantly, the current conceptualization of EA suggests that it is not negative thoughts, emotions, and sensations that are problematic, but how one responds to them that can cause difficulties.  In particular, a habitual and persistent unwillingness to experience uncomfortable thoughts and feelings (and the associated avoidance and inhibition of these experiences) is thought to be linked to a wide range of problems.
 EA has been popularized by recent third-wave cognitive-behavioral theories such as acceptance and commitment therapy (ACT). However, the general concept has roots in many other theories of psychopathology and intervention.
 Defense mechanisms were originally conceptualized as ways to avoid unpleasant affect and discomfort that resulted from conflicting motivations.  These processes were thought to contribute to the expression of various types of psychopathology.  Gradual removal of these defensive processes are thought to be a key aspect of treatment and eventually return to psychological health.
 Process-experiential therapy merges client-centered, existential, and Gestalt approaches.  Gestalt theory outlines the benefits of being fully aware of and open to one's entire experience.  One job of the psychotherapist is to "explore and become fully aware of [the patient's] grounds for avoidance" and to "[lead] the patient back to that which he wishes to avoid" (p. 142).  Similar ideas are expressed by early humanistic theory: "Whether the stimulus was the impact of a configuration of form, color, or sound in the environment on the sensory nerves, or a memory trace from the past, or a visceral sensation of fear or pleasure or disgust, the person would be 'living' it, would have it completely available to awareness…he is more open to his feelings of fear and discouragement and pain...he is more able fully to live the experiences of his organism rather than shutting them out of awareness."
 Traditional behavior therapy utilizes exposure to habituate the patient to various types of fears and anxieties, eventually resulting in a marked reduction in psychopathology.  In this way, exposure can be thought of as "counter-acting" avoidance, in that it involves individuals repeatedly encountering and remaining in contact with that which causes distress and discomfort.
 In cognitive theory, avoidance interferes with reappraisals of negative thought patterns and schema, thereby perpetuating distorted beliefs.  These distorted beliefs are thought to contribute and maintain many types of psychopathology.
 The concept of EA is explicitly described and targeted in more recent CBT modalities including acceptance and commitment therapy (ACT), dialectical behavior therapy (DBT), functional analytic psychotherapy (FAP), and behavioral activation (BA).
 Seemingly disparate forms of pathological behavior can be understood by their common function (i.e., attempts to avoid distress).  Some examples include:
 Perhaps the most significant impact of EA is its potential to disrupt and interfere with important, valued aspects of an individual's life.  That is, EA is seen as particularly problematic when it occurs at the expense of a person's deeply held values.  Some examples include:
 The Acceptance and Action Questionnaire (AAQ) was the first self-report measure explicitly designed to measure EA, but has since been re-conceptualized as a measure of "psychological flexibility".  The 62-item Multidimensional Experiential Avoidance Questionnaire (MEAQ) was developed to measure different aspects of EA. The Brief Experiential Avoidance Questionnaire (BEAQ) is a 15-item measure developed using MEAQ items, which has become the most widely used measure of experiential avoidance.