Source: Psychology 100 Finals Review Packet, The Ohio State University
Difficulty: Introductory. Prerequisites: basic familiarity with research methods (correlation, reliability, validity) and the Personality unit (factor analysis is used here too).
This section covers how psychologists define, measure, and debate intelligence. It spans the history of IQ testing (from Binet to the WAIS), the structure of intelligence (g vs. s, fluid vs. crystallised, multiple intelligences), and the fraught issues of group differences, heritability, and test bias. Understanding this material requires separating what the data show from how the data have been misused (eugenics, stereotype threat).
Intelligence is measured through IQ tests like the WAIS and Stanford-Binet. Psychologists debate whether intelligence is one general factor (g) or many specific abilities. IQ scores follow a bell curve, have been rising over time (the Flynn effect), and are influenced by both genes and environment. Group differences in scores reflect environmental and cultural factors, not simple genetic explanations.
Intelligence quotient (IQ)
A systematic means of quantifying differences among people in their intelligence. The average is set at 100.
Intelligence test
A diagnostic tool designed to measure overall thinking ability.
Abstract thinking
The capacity to understand hypothetical concepts, to reason about things that are not physically present.
g (general intelligence)
A hypothetical factor that accounts for overall differences in intellect among people. Think of it as the shared engine behind all cognitive tasks.
s (specific abilities)
Particular ability levels in narrow domains (e.g. verbal fluency, spatial reasoning). These sit alongside g.
Fluid intelligence
The capacity to learn new ways of solving problems, to reason on the fly. It tends to decline with age.
Crystallised intelligence
Accumulated knowledge of the world acquired over time. It tends to remain stable or increase with age.
Multiple intelligences
The idea (associated with Howard Gardner) that people vary in ability across different domains of intellectual skill, such as musical, bodily-kinaesthetic, and interpersonal intelligence.
Triarchic model
Robert Sternberg's model positing three distinct types of intelligence: analytical, practical, and creative.
Mental age
The age corresponding to the average individual's performance on an intelligence test. A 7-year-old who performs at the level of a typical 9-year-old has a mental age of 9.
Deviation IQ
An expression of a person's IQ relative to same-aged peers, based on how far their score deviates from the mean.
Eugenics
An early 20th-century movement to improve a population's genetic stock by encouraging reproduction among those deemed "fit" and discouraging or preventing it among those deemed "unfit." A cautionary example of science misused.
Wechsler Adult Intelligence Scale (WAIS)
The most widely used intelligence test for adults, consisting of 14 subtests assessing different types of mental abilities.
Stanford-Binet IQ test
An intelligence test based on the original measure developed by Binet and Simon, adapted by Lewis Terman of Stanford University.
Culture-fair IQ tests
Abstract reasoning items that do not depend on language and are believed to be less influenced by cultural factors than other IQ tests.
Bell curve
A distribution of scores in which most fall near the middle, with progressively fewer toward the extremes (tails). IQ scores follow this pattern.
Intellectual disability (mental retardation)
A condition characterised by onset prior to adulthood, an IQ below 70, and significant limitations in daily functioning.
Flynn effect
The finding that average IQ scores have been rising at roughly 3 points per decade across many countries. The reasons are debated but likely include better nutrition, education, and environmental complexity.
Test bias
The tendency of a test to predict outcomes better in one group than another.
Within-group heritability
The extent to which the variability of a trait within a group is genetically influenced.
Between-group heritability
The extent to which differences in a trait between groups are genetically influenced. Crucially, high within-group heritability does not imply that between-group differences are genetic.
Stereotype threat
The fear that one may confirm a negative group stereotype. This anxiety alone can depress test performance.
g (general intelligence) is the idea that one underlying factor drives performance across all cognitive tasks. s (specific abilities) are the domain-specific skills layered on top.
Fluid intelligence is raw problem-solving ability; it peaks in early adulthood and declines. Crystallised intelligence is accumulated knowledge; it holds steady or grows.
Gardner's multiple intelligences theory challenges the single-factor view, proposing at least eight distinct intelligences.
Sternberg's triarchic model splits intelligence into analytical (academic problem-solving), practical (street smarts), and creative (novel solutions).
Binet and Simon developed the first modern intelligence test in France, using the concept of mental age.
Lewis Terman adapted it into the Stanford-Binet IQ test.
The WAIS is the current gold standard for adult IQ testing, with 14 subtests.
IQ is now calculated as a deviation IQ: your score relative to your age group's average (mean = 100, standard deviation = 15).
Culture-fair IQ tests try to strip out language and cultural knowledge to measure reasoning more purely.
Scores distribute along a bell curve: most people cluster around the average.
The eugenics movement used early IQ testing to justify forced sterilisation and immigration restrictions. It remains a powerful cautionary example.
The Flynn effect shows that IQ scores have risen steadily across generations, suggesting major environmental contributions to measured intelligence.
Within-group heritability tells you how much of the variation within one group is genetic. It says nothing about why two groups might differ (that would be between-group heritability, which is much harder to establish).
Test bias means a test predicts outcomes better for one group than another. Stereotype threat is a separate phenomenon: the anxiety of potentially confirming a negative stereotype can itself lower performance.
IQ tests are used in educational placement, clinical diagnosis (intellectual disability requires an IQ below 70 plus functional impairment), and research. Understanding their limitations, cultural assumptions, and the distinction between within-group and between-group heritability is essential for interpreting results responsibly.
Students often confuse fluid and crystallised intelligence. Fluid is on-the-spot reasoning (declines with age); crystallised is accumulated knowledge (stays or grows). Picture fluid as "thinking fast" and crystallised as "knowing a lot."
High within-group heritability does not mean that differences between groups are genetic. This is one of the most commonly tested logical errors in psychology.
The Flynn effect does not mean people are getting smarter in an absolute sense. It means scores on existing tests are rising, likely due to environmental changes.
Culture-fair tests are not truly culture-free. They reduce linguistic and cultural bias, but no test eliminates it entirely.
⚠️ Know the difference between g and s, and between fluid and crystallised intelligence.
⚠️ Be able to explain why within-group heritability cannot be used to explain between-group differences.
⚠️ Know the Flynn effect and what it implies about the role of environment.
⚠️ Stereotype threat is a commonly tested concept. Know the mechanism: anxiety about confirming a stereotype impairs performance.
⚠️ Distinguish mental age from deviation IQ as two different ways of expressing test results.
True or False: Crystallised intelligence tends to decline sharply with age. Answer: False. Crystallised intelligence remains stable or increases. Fluid intelligence declines.
Fill in the blank: The finding that IQ scores have risen over generations is called the ______ effect. Answer: Flynn effect.
True or False: High within-group heritability proves that between-group differences are genetic. Answer: False. Within-group heritability says nothing about the causes of between-group differences.
Fill in the blank: The most widely used adult IQ test is the ______. Answer: Wechsler Adult Intelligence Scale (WAIS).
True or False: Stereotype threat can lower test performance even when the person is fully capable. Answer: True.
Q: A child of 8 performs at the level of a typical 10-year-old on an intelligence test. What is the child's mental age, and how does this relate to IQ?
A: The child's mental age is 10. In the original ratio IQ formula, IQ = (mental age / chronological age) x 100 = (10/8) x 100 = 125. Modern tests use deviation IQ instead, but the concept of mental age remains foundational.
Q: Why can culture-fair IQ tests not eliminate all cultural bias?
A: Because even abstract reasoning tasks are influenced by familiarity with test-taking, educational exposure, and cognitive styles that vary across cultures. "Culture-fair" reduces bias; it does not remove it.
Q: Explain why the Flynn effect is evidence for environmental influences on intelligence.
A: Genetic changes in a population happen over thousands of years, not decades. A 3-point-per-decade rise in IQ scores is far too fast to be genetic, pointing to environmental factors such as improved nutrition, schooling, and exposure to complex information.
Q: A researcher finds that IQ is 60% heritable within a particular group. Can this figure be used to explain why that group scores differently from another group? Why or why not?
A: No. Within-group heritability describes the proportion of variation within one group that is attributable to genetics. It does not address why two groups differ, since those differences could be entirely environmental.
This section traces the history of how mental illness has been understood (from demons to the medical model), introduces the major categories of disorders (anxiety, mood, personality, psychotic), and covers the key concepts needed to think about diagnosis. The diathesis-stress model is the integrating framework: most disorders arise from a combination of genetic vulnerability and environmental triggers.
Views of mental illness have evolved from demonic explanations to the medical model. Modern classification uses the DSM. Anxiety disorders (phobias, OCD, PTSD, generalised anxiety, panic disorder), mood disorders (depression, bipolar), schizophrenia, and personality disorders are the major categories. The diathesis-stress model explains most disorders as the product of genetic predisposition plus environmental stressors.
Demonic model
A historical view attributing odd behaviour, hearing voices, or talking to oneself to evil spirits. Preceded any scientific understanding of mental illness.
Medical model
The perception that mental illness is due to a physical disorder requiring medical treatment, just like any other disease.
Asylums
Institutions for the mentally ill, created in the 15th century. Conditions were often appalling.
Moral treatment
An approach to mental illness calling for dignity, kindness, and respect for patients. A reform movement against the harshness of asylums.
Deinstitutionalisation
1960s and 1970s government policy focused on releasing hospitalised psychiatric patients into the community and closing mental hospitals. Well-intentioned, but often left patients without adequate support.
Diathesis-stress model
The perspective that mental disorders are a joint product of a genetic vulnerability (the diathesis) and environmental stressors that trigger it. This is the dominant framework for understanding most disorders.
Bulimia nervosa
An eating disorder characterised by a pattern of binging and purging to lose or maintain weight.
Anorexia nervosa
An eating disorder characterised by excessive weight loss and the irrational perception that one is overweight.
Somatoform disorders
Conditions marked by physical symptoms that suggest an underlying medical illness but are psychological in origin.
Hypochondriasis
A continual preoccupation with the notion that one is suffering from a serious physical disease, despite medical reassurance.
Panic attack
A brief, intense episode of extreme fear characterised by sweating, dizziness, racing heartbeat, and feelings of impending death.
Panic disorder
Repeated and unexpected panic attacks, along with persistent worry about future attacks or behavioural changes to avoid them.
Generalised anxiety disorder (GAD)
Continual feelings of worry, anxiety, physical tension, and irritability across many areas of life.
Phobia
An intense, irrational fear of an object or situation that is greatly out of proportion to its actual threat.
Agoraphobia
Fear of being in places or situations from which escape is difficult or help unavailable, often linked to panic disorder.
Specific phobias
Intense fear of particular objects, places, or situations (e.g. spiders, heights, flying).
Social phobia
Marked fear of public situations in which embarrassment or humiliation is possible.
Posttraumatic stress disorder (PTSD)
Marked emotional disturbance after experiencing or witnessing a severely stressful event.
Obsessive-compulsive disorder (OCD)
A condition marked by repeated immersion in obsessions (intrusive, unwanted thoughts) and/or compulsions (repetitive behaviours performed to reduce distress).
Obsessions
Persistent, unwanted ideas, thoughts, or impulses that cause marked distress.
Compulsions
Repetitive behaviours or mental acts performed to reduce or prevent stress.
Anxiety sensitivity
Fear of anxiety-related sensations themselves. People high in anxiety sensitivity are frightened by their own racing heart or shortness of breath.
Major depressive episode
A state of lingering depressed mood or diminished interest in pleasurable activities, with symptoms including weight loss, sleep difficulties, and fatigue.
Cognitive model of depression
The theory that depression is caused by negative beliefs and expectations, not just by external events.
Learned helplessness
The tendency to feel helpless in the face of events perceived as uncontrollable. A classic animal-model explanation for depression.
Manic episode
An experience marked by dramatically elevated mood, decreased need for sleep, increased energy, inflated self-esteem, and impulsive behaviour.
Bipolar disorder
A condition marked by a history of at least one manic episode, typically alternating with depressive episodes.
Schizophrenia
A severe disorder of thought and emotion associated with a loss of contact with reality.
Delusions
Strongly held, fixed beliefs with no basis in reality (e.g. believing one is being monitored by the government).
Psychotic symptoms
Psychological problems reflecting serious distortions in reality, including delusions and hallucinations.
Hallucinations
Sensory perceptions that occur in the absence of an external stimulus. Auditory hallucinations (hearing voices) are the most common in schizophrenia.
Catatonic symptoms
Motor problems including extreme resistance to movement, holding the body in bizarre postures, or curling into a foetal position.
Personality disorder
A condition in which personality traits, appearing first in adolescence, are inflexible, stable across situations, and cause distress or impairment.
Borderline personality disorder
Marked by extreme instability in mood, identity, and impulse control.
Psychopathic personality
Marked by superficial charm, dishonesty, manipulativeness, self-centredness, and risk-taking.
Antisocial personality disorder
Marked by a lengthy history of irresponsible and/or illegal actions, starting in adolescence.
Demonic model came first: unusual behaviour was attributed to evil spirits.
The medical model reframed mental illness as a disease requiring treatment.
Asylums (15th century onward) housed the mentally ill, often in terrible conditions.
Moral treatment was a reform movement advocating humane care.
Deinstitutionalisation (1960s–1970s) closed many institutions, but community support was often inadequate.
Generalised anxiety disorder: chronic, free-floating worry across many domains.
Panic disorder: recurring unexpected panic attacks, plus persistent fear of more attacks.
Agoraphobia: avoidance of places where escape or help might be unavailable.
Specific phobias: intense fear of a particular object or situation (e.g. heights, spiders).
Social phobia: fear of social situations where embarrassment might occur.
OCD: obsessions (intrusive thoughts) and/or compulsions (repetitive behaviours to relieve distress).
PTSD: emotional disturbance following a severe traumatic event.
Anxiety sensitivity is a risk factor: people who fear their own anxiety symptoms are more vulnerable.
Major depressive episode: prolonged low mood, loss of interest, sleep and appetite changes.
The cognitive model of depression says negative beliefs and expectations maintain the disorder.
Learned helplessness: feeling unable to influence outcomes, a pathway into depression.
Manic episode: elevated mood, high energy, impulsiveness, reduced need for sleep.
Bipolar disorder: at least one manic episode, usually alternating with depressive episodes.
A severe disorder involving psychotic symptoms: delusions (fixed false beliefs), hallucinations (sensory experiences without external input), and catatonic symptoms (motor disturbances).
Schizophrenia is not the same as dissociative identity disorder (split personality). This is one of the most widespread misconceptions in psychology.
Anorexia nervosa: extreme weight loss with distorted body perception.
Bulimia nervosa: cycles of binging and purging.
Physical symptoms with no identifiable medical cause.
Hypochondriasis: persistent belief that one has a serious illness despite medical reassurance.
Personality traits that are inflexible, stable, present from adolescence, and cause significant distress.
Borderline personality disorder: instability in mood, identity, and impulse control.
Antisocial personality disorder: long history of irresponsible or illegal behaviour.
Psychopathic personality: superficial charm, dishonesty, manipulation, and lack of empathy.
Most disorders are best understood as a combination of genetic vulnerability (diathesis) and environmental stressors. Neither alone is usually sufficient.
Schizophrenia does not mean "split personality." That confusion stems from the word's Greek roots ("split mind"), but the disorder involves a break from reality, not multiple identities.
Students often mix up panic attacks and panic disorder. A panic attack is a single episode; panic disorder is a pattern of recurring attacks plus worry about future ones.
OCD is not the same as being tidy or organised. Clinical OCD involves distressing, time-consuming obsessions and compulsions that significantly impair functioning.
Antisocial personality disorder and psychopathic personality overlap but are not identical. Antisocial PD is defined by behaviour (law-breaking, irresponsibility); psychopathy emphasises personality traits (charm, manipulation, low empathy).
⚠️ The diathesis-stress model is a unifying concept tested across many disorders. Know how it works and be able to apply it to a specific disorder.
⚠️ Distinguish the anxiety disorders from one another: GAD (general worry), panic disorder (recurring attacks), phobias (specific fears), OCD (obsessions/compulsions), PTSD (trauma response).
⚠️ Know the key symptoms of schizophrenia: delusions, hallucinations, catatonic symptoms.
⚠️ The cognitive model of depression and learned helplessness are two commonly tested explanations for depression.
⚠️ Bipolar disorder requires at least one manic episode. Depression alone is not bipolar.
True or False: Schizophrenia is the same as having multiple personalities. Answer: False. Schizophrenia involves psychotic symptoms (delusions, hallucinations). Multiple personalities is dissociative identity disorder.
Fill in the blank: The model that explains mental disorders as a combination of genetic vulnerability and environmental stress is the ______ model. Answer: Diathesis-stress model.
True or False: Bipolar disorder can be diagnosed based on depressive episodes alone. Answer: False. At least one manic episode is required.
Fill in the blank: Persistent, unwanted thoughts that cause distress are called ______; repetitive behaviours performed to reduce that distress are called ______. Answer: Obsessions; compulsions.
True or False: Deinstitutionalisation successfully provided all former patients with adequate community support. Answer: False. Many patients ended up without proper support or housing.
Q: A patient experiences weeks of elevated mood, decreased need for sleep, and impulsive spending, followed by a period of deep sadness and withdrawal. What is the most likely diagnosis?
A: Bipolar disorder. The elevated phase describes a manic episode, and the low phase is consistent with a depressive episode.
Q: How does the diathesis-stress model account for the fact that not everyone with a family history of depression becomes depressed?
A: The model holds that genetic vulnerability (diathesis) is necessary but not sufficient. Without significant environmental stressors to activate the vulnerability, the disorder may never develop.
Q: A person fears they are seriously ill despite repeated medical tests showing nothing wrong. What condition is this, and under what category does it fall?
A: Hypochondriasis, a somatoform disorder. The physical preoccupation has a psychological rather than medical origin.
Q: Distinguish between agoraphobia and specific phobias.
A: Agoraphobia is fear of situations from which escape is difficult or help unavailable (often linked to panic disorder). Specific phobias are intense fears of particular objects or situations (e.g. snakes, heights). Agoraphobia is about situations in general; specific phobias are about a defined trigger.
Intelligence connects to Personality (factor analysis is the shared statistical method; personality traits can influence test-taking behaviour and academic motivation) and to Social Psychology (stereotype threat links IQ research to prejudice and group dynamics). Psychological Disorders connects to Psych Treatments (the next doc covers the therapies designed for these disorders) and to Stress and Health (stress is a trigger in the diathesis-stress model, and disorders like PTSD sit at the intersection of stress research and clinical psychology).
IQ, intelligence quotient, WAIS, Stanford-Binet, g factor, general intelligence, specific abilities, fluid intelligence, crystallised intelligence, multiple intelligences, Gardner, triarchic model, Sternberg, mental age, deviation IQ, eugenics, Flynn effect, bell curve, culture-fair test, test bias, within-group heritability, between-group heritability, stereotype threat, demonic model, medical model, asylums, moral treatment, deinstitutionalisation, diathesis-stress, bulimia nervosa, anorexia nervosa, somatoform, hypochondriasis, panic attack, panic disorder, GAD, phobia, agoraphobia, social phobia, PTSD, OCD, obsessions, compulsions, anxiety sensitivity, depression, cognitive model, learned helplessness, manic episode, bipolar disorder, schizophrenia, delusions, hallucinations, catatonic, personality disorder, borderline, antisocial, psychopathy