M05.06.02 Type A and B Personalities

This section provides an overview of intelligence and personality testing commonly encountered in medical settings. Understanding these assessments is crucial for medical students to interpret and integrate test results into patient care.

Intelligence Testing

• Intelligence Quotient (IQ): A standardized score estimating a person’s general intellectual ability compared to others of the same age.
  • Calculation:
    • Mental age (MA) method: IQ = MA/CA (chronological age) × 100
    • Deviation from the norm method: Mean IQ = 100, Standard Deviation (SD) = 15
      • Intellectual disability: < 2 SD below the mean
  • Distribution: Bell-shaped curve with a mean of 100 and an SD of 15.
  • Heritability: Estimated to be around 70%, with recent studies suggesting a maternal influence.
  • Limitations: IQ is not an absolute measure of intelligence but a relative score within a population.

Commonly Used IQ Tests:

• Wechsler Adult Intelligence Scale, Revised (WAIS-R): For adults aged 17 and above.
• Wechsler Intelligence Scale for Children, Revised (WISC-R): For children aged 6-17.
• Wechsler Preschool and Primary Scale of Intelligence (WPPSI): For children aged 4-6.
• Stanford-Binet Scale: For children aged 2-18 (particularly useful for younger children, those with impairments, and the very gifted).

Table 6-2. Distribution of IQ Scores in the General Population

Personality Testing

Personality tests assess characteristic patterns of thoughts, feelings, and behaviors. Two main categories exist:

• Objective Tests:
  • Utilize standardized stimuli (questions) and limited response options.
  • Scored mechanically using a key, requiring no clinical expertise.
  • Results are interpreted by comparing them to established norms (e.g., Minnesota Multiphasic Personality Inventory-2 ).
• Projective Tests:
  • Utilize ambiguous stimuli (e.g., inkblots, pictures) with a wide range of possible responses.
  • Relies on clinical interpretation based on established associations between responses and personality characteristics.
  • Requires experienced clinicians for scoring using standardized methods.

Examples of Projective Tests:

• Rorschach inkblot test
• Thematic Apperception Test (TAT)
• Sentence completion test
• Projective drawings (house-tree-person)

Note:

• Stanford-Binet (1905) was the first formal IQ test for children.
• MMPI-2 is the most widely used personality test.

Bibliography:

• Kaplan, HI, & Sadock, BJ. (2007). Synopsis of Psychiatry (10th ed.). Lippincott Williams & Wilkins.
• Wechsler, D. (1981). WAIS-R: Wechsler Adult Intelligence Scale—Revised. The Psychological Corporation.
• Wechsler, D. (1989). WISC-R manual: Wechsler Intelligence Scale for Children—Revised. The Psychological Corporation.