Intolerance of Uncertainty Scale

The Intolerance of Uncertainty Scale (IUS-27) is a validated self-report questionnaire widely used in cognitive behavioral therapy to measure how an…

Questions: 27
Duration: 10 min
Original title: IUS-27 — Intolerance of Uncertainty Scale
Adaptation: Intolerance of Uncertainty Scale
Authors: Freeston, M.H., Rhéaume, J., Letarte, H., Dugas, M.J., & Ladouceur, R.
Created: 1994

The Intolerance of Uncertainty Scale (IUS-27) is a validated self-report questionnaire widely used in cognitive behavioral therapy to measure how an individual responds to ambiguous, unpredictable, or novel situations. Originally developed to understand the cognitive mechanisms underlying generalized anxiety disorder, it captures a dispositional trait where uncertainty is perceived as unacceptable and threatening, regardless of the actual probability of a negative outcome.

For clinicians, the IUS-27 is an essential tool to formulate anxiety disorders and obsessive-compulsive traits. It helps map the rigid limiting beliefs that fuel daily anxiety and drive patients toward excessive worry or paralysis. By tracking this construct over time, clinicians can measure the shift from rigid experiential avoidance toward greater psychological flexibility.

Example result

Fictitious result, computed from a sample set of answers.

Overall score

78/ 135

A 27-item self-report questionnaire assessing emotional, cognitive, and behavioral reactions to uncertainty and ambiguous situations, the perceived implications of being uncertain, and attempts to control the future. The IUS is a self-administered questionnaire comprising 27 items that focus on emotional, cognitive, and behavioral reactions to ambiguous situations, the implications of uncertainty, and attempts to control the future. Developed within Dugas and Ladouceur's cognitive-behavioral model of generalized anxiety disorder (GAD), intolerance of uncertainty is conceptualized therein as a core variable of excessive worry. Intended for adults, in initial assessment and treatment monitoring.

cliniquemixed · condition: generalized anxiety disorder · adults with GAD seeking psychotherapy (81.5% women) · Canada · n = 108 · 2025

27135

M = 87.1 ± 19.78

cliniquemixed · condition: generalized anxiety disorder · before videoconference CBT · Canada · n = 46 · 2021 · Marcotte-Beaumier et al. (2021)

27135

M = 83.67 ± 20

Scoring

Sum (unifactorial) or sum by subscale (bifactorial), total score from 27 to 135, each item is scored on a 5-point scale (from 1 to 5).

Uncertainty has negative implications for self-perception and behaviors

46/ 75

Belief that uncertainty has negative consequences on behavior and self-image.

items 1, 2, 3, 9, 12, 13, 14, 15, 16, 17, 20, 22, 23, 24, 25

1575

Uncertainty is unfair and spoils everything

32/ 60

Belief that uncertainty is unfair and spoils everything.

items 4, 5, 6, 7, 8, 10, 11, 18, 19, 21, 26, 27

1260

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What the test measures

The IUS-27 measures the trait of intolerance of uncertainty by breaking it down into distinct cognitive, emotional, and behavioral facets. High scores reflect a persistent difficulty in tolerating the unknown, often manifesting as maladaptive control-seeking patterns.

Emotional distress: The degree to which ambiguous situations elicit feelings of anxiety, frustration, or vulnerability.
Cognitive paralysis: The tendency for doubt to disrupt decision-making and prevent the person from forming a firm opinion.
Behavioral inhibition: The inability to take action or function effectively when outcomes are not guaranteed.
Unfairness of uncertainty: The rigid belief that life should be fully predictable and that surprises are inherently negative or unjust.

This instrument is intended for use with adult populations in clinical and research settings, particularly those presenting with generalized anxiety, chronic worry, or related emotional disorders.

When and why to use it

Clinicians typically administer the IUS-27 when excessive worry or a need for absolute predictability becomes a central clinical issue. It is particularly useful for identifying the underlying maintaining processes that keep anxiety cycles active.

Intake baseline: To quantify the patient's difficulty with uncertainty, which often differentiates generalized anxiety from other symptom presentations.
Treatment planning: To help patients recognize their intolerance before initiating behavioral experiments designed to challenge automatic thoughts about the unknown.
Monitoring change: To evaluate whether the patient is successfully learning to tolerate productive discomfort over the course of therapy.
Targeting rigid rules: To pinpoint specific beliefs (e.g., "I must know what will happen tomorrow") that require targeted cognitive restructuring.

Using a validated score provides a structured, objective metric of this underlying vulnerability trait, adding precision to clinical impressions of worry and allowing for standardized tracking of treatment efficacy.

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The questions

You will find below a series of statements which describe how people may react to the uncertainties of life. Please use the scale to describe to what extent each item is characteristic of you.
1. Uncertainty prevents me from taking a stand.
Explores whether the unknown prevents the individual from solidifying their viewpoints.
- Not at all characteristic
- A little characteristic
- Somewhat characteristic
- Very characteristic
- Entirely characteristic
2. Being uncertain means you are a disorganized person.
Probes the belief that a lack of absolute clarity equates to personal chaos.
- Not at all characteristic
- A little characteristic
- Somewhat characteristic
- Very characteristic
- Entirely characteristic
3. Uncertainty makes life unbearable.
Assesses the catastrophic view that life is unbearable without predictability.
- Not at all characteristic
- A little characteristic
- Somewhat characteristic
- Very characteristic
- Entirely characteristic
4. It's unfair not to have guarantees in life.
Examines the sense of injustice directed at life's inherent lack of certainty.
- Not at all characteristic
- A little characteristic
- Somewhat characteristic
- Very characteristic
- Entirely characteristic
5. I can't relax until I know what will happen tomorrow.
Evaluates the degree to which future unpredictability drives persistent mental tension.
- Not at all characteristic
- A little characteristic
- Somewhat characteristic
- Very characteristic
- Entirely characteristic
6. Uncertainty makes me uncomfortable, anxious, or stressed.
Measures the direct emotional distress triggered by ambiguous situations.
- Not at all characteristic
- A little characteristic
- Somewhat characteristic
- Very characteristic
- Entirely characteristic
7. I am extremely bothered by unexpected events.
Captures the intensity of the negative emotional response to unexpected occurrences.
- Not at all characteristic
- A little characteristic
- Somewhat characteristic
- Very characteristic
- Entirely characteristic
8. It frustrates me not to have all the information I need.
Probes the frustration arising from incomplete data or partial answers.
- Not at all characteristic
- A little characteristic
- Somewhat characteristic
- Very characteristic
- Entirely characteristic
9. Uncertainty prevents me from fully enjoying life.
Assesses whether the need for certainty restricts the individual's overall life engagement.
- Not at all characteristic
- A little characteristic
- Somewhat characteristic
- Very characteristic
- Entirely characteristic
10. One should anticipate everything to avoid surprises.
Examines the rigid rule that hyper-vigilance is required to prevent the unexpected.
- Not at all characteristic
- A little characteristic
- Somewhat characteristic
- Very characteristic
- Entirely characteristic
11. A small, unexpected event can ruin everything, even the best of plans.
Evaluates the fragile belief that minor surprises ruin otherwise well-planned endeavors.
- Not at all characteristic
- A little characteristic
- Somewhat characteristic
- Very characteristic
- Entirely characteristic
12. When it's time to act, uncertainty paralyzes me.
Measures the behavioral inhibition experienced when a guaranteed outcome is absent.
- Not at all characteristic
- A little characteristic
- Somewhat characteristic
- Very characteristic
- Entirely characteristic
13. Being uncertain means that I'm not good enough.
Probes the conditional assumption that experiencing doubt is a mark of inferiority.
- Not at all characteristic
- A little characteristic
- Somewhat characteristic
- Very characteristic
- Entirely characteristic
14. When I am uncertain, I can't move forward.
Explores the tendency to halt all progress when confronted with ambiguity.
- Not at all characteristic
- A little characteristic
- Somewhat characteristic
- Very characteristic
- Entirely characteristic
15. When I am uncertain, I can't function well.
Assesses the subjective impairment in daily functioning caused by a lack of clarity.
- Not at all characteristic
- A little characteristic
- Somewhat characteristic
- Very characteristic
- Entirely characteristic
16. Unlike me, other people always seem to know where they are going in life.
Examines the negative social comparison regarding others' perceived certainty.
- Not at all characteristic
- A little characteristic
- Somewhat characteristic
- Very characteristic
- Entirely characteristic
17. Uncertainty makes me feel vulnerable, unhappy, or sad.
Captures the depressive or dysphoric emotional toll of living with the unknown.
- Not at all characteristic
- A little characteristic
- Somewhat characteristic
- Very characteristic
- Entirely characteristic
18. I always want to know what the future has in store for me.
Evaluates the compulsive need to predict and control future events.
- Not at all characteristic
- A little characteristic
- Somewhat characteristic
- Very characteristic
- Entirely characteristic
19. I hate being caught off guard.
Probes the visceral intolerance for sudden or unanticipated situations.
- Not at all characteristic
- A little characteristic
- Somewhat characteristic
- Very characteristic
- Entirely characteristic
20. The slightest doubt can stop me from acting.
Measures how even minor ambiguities trigger significant behavioral avoidance.
- Not at all characteristic
- A little characteristic
- Somewhat characteristic
- Very characteristic
- Entirely characteristic
21. I should be able to organize everything in advance.
Examines the perfectionistic demand for total proactive control over one's life.
- Not at all characteristic
- A little characteristic
- Somewhat characteristic
- Very characteristic
- Entirely characteristic
22. Being uncertain means that I lack confidence.
Explores the core belief that self-assurance is incompatible with experiencing doubt.
- Not at all characteristic
- A little characteristic
- Somewhat characteristic
- Very characteristic
- Entirely characteristic
23. I find it unfair that other people seem certain about their future.
Assesses the sense of inequality felt when comparing one's own doubt to others' apparent certainty.
- Not at all characteristic
- A little characteristic
- Somewhat characteristic
- Very characteristic
- Entirely characteristic
24. Uncertainty keeps me from sleeping well.
Evaluates the physiological and sleep-related impact of unresolved worries.
- Not at all characteristic
- A little characteristic
- Somewhat characteristic
- Very characteristic
- Entirely characteristic
25. I have to withdraw from any uncertain situation.
Captures the drive for total experiential avoidance when facing the unpredictable.
- Not at all characteristic
- A little characteristic
- Somewhat characteristic
- Very characteristic
- Entirely characteristic
26. The ambiguities of life stress me out.
Probes the generalized stress response to inherently unclear circumstances.
- Not at all characteristic
- A little characteristic
- Somewhat characteristic
- Very characteristic
- Entirely characteristic
27. I can't stand being undecided about my future.
Measures the acute discomfort associated with lacking a definitive life plan.
- Not at all characteristic
- A little characteristic
- Somewhat characteristic
- Very characteristic
- Entirely characteristic