Defining, explaining and classifying psychological disorders

What the exam asks

• Section I (Multiple Choice): Expect short scenarios where you must identify whether a behavior meets the criteria for a disorder (dysfunction, distress, deviation), match an explanation of a person’s symptoms to one of the seven psychological perspectives or integrative models (biopsychosocial, diathesis-stress), or distinguish between the DSM and ICD.
• Section II (EBQ and AAQ): In the EBQ, the diathesis-stress model, biopsychosocial model, diagnostic stigma, or any of the seven perspectives are useful concepts to apply in Parts B(ii) and C(ii) when explaining how research evidence supports your claim. In the AAQ, cultural norms and diagnostic bias frequently link to generalizability (Part E).

Core ideas

Defining a psychological disorder (The 3 Ds)

Psychologists evaluate three criteria—always within the context of a person’s culture and developmental stage—before identifying a pattern of thoughts, feelings, or behaviors as a disorder:

1. Level of dysfunction (maladaptiveness): Does the behavior interfere with everyday functioning, such as holding a job, attending school, or maintaining relationships? (This is the most critical clinical criterion.)
2. Perception of distress: Does the behavior cause significant emotional pain, suffering, or subjective discomfort to the individual or others?
3. Deviation from social norms: Is the behavior statistically atypical or contrary to the cultural expectations of the person’s society? Deviation alone never defines a disorder; an eccentric hobby or culturally sanctioned grief ritual is not pathological unless accompanied by dysfunction or distress.

Classification and diagnosis

Diagnosing a psychological disorder requires specialized clinical training and evidence-based assessment tools (such as structured interviews and standardized psychometric tests) to ensure reliability and validity.