2025 IB DP Psychology Practice Paper with Answers

Neuroplasticity refers to the brain's capacity to reorganize its neural pathways and adapt its structure as a result of experience, learning, or environmental demands. This involves mechanisms such as dendritic branching (where new synaptic connections are formed) and synaptic pruning (where unused connections are eliminated). A key study demonstrating this is Draganski et al. (2004). The researchers aimed to investigate whether learning a new skill (juggling) would lead to structural changes in the brain. They used a sample of 24 non-jugglers who underwent a baseline structural MRI scan. Half of the participants were taught to juggle and practiced for three months, while the other half served as a control group. A second MRI scan was conducted after three months, and a final scan was done three months after the jugglers had stopped practicing. The results showed that the juggling group had a significant increase in grey matter in the mid-temporal area of both hemispheres, an area associated with visual memory and movement. Three months after stopping practice, this grey matter had decreased. The control group showed no changes. This study demonstrates neuroplasticity because it shows that the physical structure of the brain dynamically adapted (increased in grey matter density) in response to learning a new motor skill, and subsequently underwent pruning when the environmental demand (practice) was removed.

Marks are awarded using the standard IB psychology SAQ rubric (9 marks total): [1 to 3 marks] The response defines neuroplasticity accurately, explaining concepts like dendritic branching or synaptic pruning, showing basic understanding of the biological mechanism. [4 to 6 marks] The response describes a relevant study (e.g., Draganski et al. or Maguire et al.) with accurate details of the aim, method, and results. [7 to 9 marks] The response clearly explains how the findings of the chosen study demonstrate neuroplasticity, drawing a direct link between the behavioral change/experience and the physical brain changes observed.

Schema theory states that our mind organizes information into mental frameworks called schemas, which are based on past experiences and help us process new information quickly. These schemas influence cognitive processing, particularly encoding and retrieval, by allowing us to predict expectations; however, this can lead to distortions because memory is reconstructive rather than photographic. This was demonstrated in a study by Brewer and Treyens (1981), who investigated the role of schemas in the retrieval of spatial memory. Eighty-six university students were left in an office for 35 seconds. The room contained typical office objects (schema-consistent items like a typewriter and desk) and highly atypical objects (schema-inconsistent items like a skull), as well as missing objects that are typically found in offices (like books). Participants were then asked to write down everything they could remember. The results showed that participants were highly likely to recall typical office items, and many recalled typical items that were not actually present, such as books. This occurred because their pre-existing schema of an office influenced their active reconstruction of the scene, causing them to falsely insert schema-consistent items to make sense of the memory. This study illustrates schema theory by showing that memory is not a passive recording but an active reconstruction heavily influenced by pre-existing cognitive schemas.

Marks are awarded using the standard IB psychology SAQ rubric (9 marks total): [1 to 3 marks] The response accurately explains the concept of schemas, detailing their function in processing information, saving cognitive energy, and/or causing distortion through reconstruction. [4 to 6 marks] The response provides an accurate description of a relevant study (e.g., Brewer and Treyens, 1981), detailing its aim, procedure, and results. [7 to 9 marks] The response links the study's results back to schema theory, showing how schema-driven processing directly accounts for the specific memory distortions observed in the study.

Social Cognitive Theory (SCT), proposed by Albert Bandura, argues that humans learn behavior through the observational learning of models in their environment. This process is mediated by cognitive factors. For observational learning to occur, four conditions must be met: Attention (noticing the model's behavior), Retention (remembering what was observed), Reproduction (having the physical and mental ability to replicate the behavior), and Motivation (having a reason to mimic the behavior, often influenced by vicarious reinforcement or identification with the model). Bandura, Ross and Ross (1961) demonstrated this theory in their Bobo Doll experiment. They aimed to see if children would learn and imitate aggressive behavior through observation. Children aged 3 to 6 were divided into groups: one group watched an adult model behave aggressively toward a Bobo doll (beating, kicking, and shouting), another watched a non-aggressive model playing quietly, and a control group watched no model. When the children were placed alone in a room with the Bobo doll, those who had observed the aggressive model imitated the exact aggressive actions and words of the model. This study supports Social Cognitive Theory because it clearly demonstrates observational learning; the children paid attention, retained the information, and reproduced the behavior, motivated by their identification with the adult model and the absence of any negative consequences.

Marks are awarded using the standard IB psychology SAQ rubric (9 marks total): [1 to 3 marks] The response explains the basic mechanisms of Social Cognitive Theory, identifying key concepts such as observational learning, modeling, and the cognitive mediational processes (attention, retention, reproduction, and motivation). [4 to 6 marks] The response describes a relevant study (e.g., Bandura et al., 1961) with accurate details regarding the design, sample, and findings. [7 to 9 marks] The response explicitly links the study's findings back to Social Cognitive Theory, explaining how the observed imitation demonstrates the cognitive processes of observational learning.

### Essay Plan & Content Guide

#### 1. Introduction
* **Define thinking and decision-making:** Thinking is the process of using information and creating new ideas, while decision-making is the cognitive process of identifying and choosing alternatives based on values, preferences, and beliefs.
* **Introduce the Dual Process Model (DPM):** Developed by Stanovich and West (2000) and popularized by Daniel Kahneman (2011), the model suggests that thinking is split into two distinct modes: System 1 (intuitive, automatic, fast, unconscious, requiring low cognitive effort) and System 2 (rational, deliberate, slow, conscious, requiring high cognitive effort).
* **Thesis Statement:** While the Dual Process Model provides a highly predictive and empirically supported framework for understanding cognitive shortcuts and decision-making errors, it has been criticized for being overly reductionist, conceptually vague, and lacking clear neurobiological differentiation.

#### 2. Description of the Model
* **System 1 Thinking:** Operates automatically and quickly, with little or no effort and no sense of voluntary control. It relies on heuristics (mental shortcuts) to make rapid decisions under pressure or with limited information. It is prone to systematic errors (cognitive biases).
* **System 2 Thinking:** Allocates attention to the effortful mental operations that demand it. It is slower, analytical, rule-governed, and logical. It can override the intuitive responses generated by System 1, but this process requires significant working memory capacity and cognitive effort (which is limited, leading to cognitive laziness).

#### 3. Empirical Support
* **Study 1: Wason Selection Task (Wason, 1968)**
* *Aim:* To investigate the difficulty of making logical decisions using abstract tasks and the role of intuitive matching bias (System 1).
* *Procedure:* Participants are shown four cards (e.g., A, K, 4, 7) and given a rule: "If a card has a vowel on one side, then it has an even number on the other side." They must decide which card(s) to turn over to test the rule.
* *Findings:* Most participants incorrectly chose 'A' and '4' (relying on matching bias, a System 1 heuristic). The correct logical answer is 'A' and '7' (which requires System 2 logic to falsify the hypothesis).
* *Link to DPM:* This demonstrates that abstract reasoning often triggers an automatic, error-prone System 1 response unless concrete, real-world context (such as the drinking age version by Cox and Griggs, 1982) is provided to activate System 2.

* **Study 2: Alter et al. (2007)**
* *Aim:* To investigate whether cognitive disfluency (difficulty in reading) triggers System 2 thinking.
* *Procedure:* Participants completed the Cognitive Reflection Test (CRT), which consists of trick questions that have intuitive but incorrect answers (e.g., "A bat and a ball cost $1.10. The bat costs $1.00 more than the ball. How much does the ball cost?"). Half the participants read the test in an easy-to-read, clear font (fluent condition), while the other half read it in a difficult, light grey, italicized font (disfluent condition).
* *Findings:* Participants in the disfluent condition answered significantly more questions correctly than those in the fluent condition.
* *Link to DPM:* The physical difficulty of reading the text acted as a cognitive cue that disengaged the automatic, error-prone System 1 processing and mobilized the analytical, deliberate System 2 processing.

#### 4. Critical Evaluation
* **Strengths:**
* **High Empirical Validity:** Strongly supported by numerous laboratory experiments (e.g., Stroop effect, anchoring studies, Wason Selection Task).
* **Practical Applicability:** Successfully explains real-world phenomena such as economic behaviors (behavioral economics), marketing strategies, clinical diagnostic errors by doctors, and stereotyping/prejudice.
* **Predictive Power:** Accounts for why highly intelligent individuals still make irrational or biased decisions under specific constraints (e.g., time pressure, high cognitive load).

* **Limitations:**
* **Reductionism:** Reducing human cognition to just two systems is highly simplistic. Human thinking may occur on a continuous spectrum rather than in discrete, compartmentalized boxes.
* **Construct Validity (Vagueness):** It is difficult to define and measure where System 1 ends and System 2 begins. Some features of System 1 (like fast execution) can also characterize highly trained System 2 skills (e.g., an expert chess player making a rapid, complex move).
* **Biological Reductionism:** Though neuroimaging (fMRI) studies show different brain regions active during different tasks (e.g., prefrontal cortex for analytical tasks), there is no clear evidence of two distinct, isolated physical systems in the brain corresponding to System 1 and System 2.
* **Role of Emotion:** The model largely ignores the interaction between emotion and cognition (e.g., Antonio Damasio’s Somatic Marker Hypothesis argues that emotional signals are crucial for rational decision-making, which blurs the boundary between System 1 and System 2).

#### 5. Conclusion
* Summarize the main arguments: The Dual Process Model is an invaluable framework for understanding the duality of human choice—balancing speed with accuracy.
* Final judgment: While the labels "System 1" and "System 2" are useful metaphorical constructs rather than physical brain entities, the model’s empirical robustness ensures its central place in cognitive psychology.

### IB Diploma Programme Assessment Criteria for ERQs (22 Marks)

#### Criterion A: Focus on the question (2 marks)
* **2 marks:** The response is fully focused on the question, with a clear thesis statement and a consistently sustained argument regarding the strengths and limitations of the Dual Process Model.
* **1 mark:** The response is partially focused, or identifies the model but drifts into unrelated topics.

#### Criterion B: Knowledge and understanding (6 marks)
* **5-6 marks:** The response demonstrates detailed and accurate knowledge and understanding of the Dual Process Model (clearly outlining the characteristics of System 1 and System 2, heuristics, cognitive load, and the interaction between the systems).
* **3-4 marks:** The response demonstrates acceptable knowledge of the model, but with minor omissions, inaccuracies, or a lack of depth in explaining the mechanisms.
* **1-2 marks:** Knowledge is superficial, inaccurate, or highly limited.

#### Criterion C: Use of research to support decimals/arguments (6 marks)
* **5-6 marks:** Relevant empirical studies (e.g., Wason, 1968; Alter et al., 2007; Kahneman and Tversky) are accurately described (aims, procedures, findings) and explicitly linked to the features of the Dual Process Model.
* **3-4 marks:** Research is cited and described but may contain minor inaccuracies, or the connection between the study and the model is not fully developed.
* **1-2 marks:** Descriptive studies are mentioned but are largely irrelevant, highly inaccurate, or unlinked to the question.

#### Criterion D: Critical thinking (6 marks)
* **5-6 marks:** The response showcases critical evaluation of the model, covering strengths (e.g., application to economics, predictive power) and limitations (e.g., reductionism, lack of neurobiological evidence, construct validity, omission of emotion). Analytical points are balanced, coherent, and well-justified.
* **3-4 marks:** Evaluation is present but may be superficial, generic (e.g., standard "unethical" or "low ecological validity" critiques that do not target the model itself), or one-sided.
* **1-2 marks:** Evaluation is absent or contains only extremely basic or circular statements.

#### Criterion E: Clarity and organisation (2 marks)
* **2 marks:** The essay is logically structured (Introduction, Description, Evidence, Evaluation, Conclusion), uses appropriate psychological terminology throughout, and flows smoothly.
* **1 mark:** The essay has some structure but lacks clear signposting, paragraphs, or logical flow.

### Introduction
- **Define the disorder**: Major Depressive Disorder (MDD) is a mood disorder characterized by persistent low mood, anhedonia (loss of interest or pleasure), fatigue, changes in sleep and appetite, and feelings of worthlessness.
- **Introduce biological explanations**: Biological etiologies suggest that MDD is caused by physiological factors. The two primary explanations are:
1. **Genetic vulnerability**: The inheritance of specific genes that make an individual more susceptible to depression.
2. **Neurochemical imbalances (The Serotonin Hypothesis)**: The idea that low levels of serotonin in the synaptic cleft lead to depressive symptoms.
- **Thesis**: While biological factors provide strong, empirical explanations for MDD, they are reductionist when considered in isolation. A holistic model, such as the Diathesis-Stress Model, is necessary to fully explain the onset of the disorder.

### Explanation 1: Genetic Vulnerability
- **Theory**: Genetics suggests that MDD can be inherited through generations. Rather than a single 'depression gene', it is believed to be polygenic, involving multiple genes that interact with environmental factors.
- **Key Study - Kendler et al. (2006)**:
- **Aim**: To investigate the heritability of MDD in a large sample of twins.
- **Method**: Telephone interviews of over 42,000 Swedish twins.
- **Findings**: The researchers found a concordance rate of 42% for female MZ twins and 29% for male MZ twins, compared to 11% and 30% for DZ twins respectively. Overall heritability was estimated at around 38%.
- **Conclusion**: MDD is moderately heritable, with a higher genetic predisposition in females than males.
- **Evaluation of Genetic Explanation**:
- *Strengths*: Large sample size increases generalizability; twin studies control for many confounding variables.
- *Limitations*: Concordance rates are not 100%, indicating that genetics alone cannot explain the disorder. Environmental factors must play a role.

### Explanation 2: Gene-Environment Interaction (GxE)
- **Theory**: The serotonin transporter gene (5-HTT) is responsible for the reuptake of serotonin. A mutation in this gene (short alleles versus long alleles) affects how individuals handle stress.
- **Key Study - Caspi et al. (2003)**:
- **Aim**: To investigate whether a mutation in the 5-HTT gene combined with stressful life events increases the risk of depression.
- **Method**: Longitudinal study of 847 New Zealand participants. Group 1 had two short alleles; Group 2 had one short and one long allele; Group 3 had two long alleles.
- **Findings**: Participants with one or two short alleles who experienced multiple stressful life events were significantly more likely to develop depression than those with two long alleles.
- **Conclusion**: Genetics (5-HTT) interacts with environmental stress to trigger depression, supporting the Diathesis-Stress Model.
- **Evaluation of Caspi et al. (2003)**:
- *Strengths*: Highly longitudinal, naturalistic setting.
- *Limitations*: Self-reported stressful life events may be subject to memory bias. Some replication studies have failed to find the same strong association, suggesting a complex pathway.

### Explanation 3: Neurochemical Explanation (The Serotonin Hypothesis)
- **Theory**: Serotonin is a neurotransmitter involved in mood regulation. Low levels of serotonin or a lack of sensitivity in post-synaptic receptors are hypothesized to cause MDD.
- **Key Evidence**: The success of Selective Serotonin Reuptake Inhibitors (SSRIs) like Prozac, which block the reuptake of serotonin, leaving more in the synaptic cleft and easing depressive symptoms.
- **Evaluation of Neurochemical Explanation**:
- *Strengths*: Practical application in pharmaceutical treatments, which have helped millions of patients worldwide.
- *Limitations*: Treatment etiology fallacy (just because SSRIs alleviate symptoms does not mean a lack of serotonin caused the disorder in the first place). There is a 'therapeutic delay' (SSRI chemical changes occur within hours, but psychological improvement takes weeks), suggesting downstream neurogenesis or cognitive changes are required.

### Critical Discussion & Synthesis
- **Reductionism vs. Holism**: Purely biological explanations are reductionist because they reduce complex human behaviors to neurotransmitters and DNA, ignoring cognitive distortions (Beck's triad) and sociocultural stressors (poverty, relationship breakdowns).
- **Biopsychosocial Approach**: The Diathesis-Stress Model offers a more robust framework. Biology provides the vulnerability (diathesis), but environmental stressors (sociocultural) and negative schema (cognitive) trigger the actual onset of depression.
- **Ethical Considerations**: Genetic determinism may lead to self-fulfilling prophecies or genetic stigmatization.

### Conclusion
- Summarize that biological explanations (genetics, 5-HTT gene, serotonin hypothesis) provide essential insights into MDD.
- Emphasize that because biological mechanisms cannot fully account for the disorder on their own, they must be integrated with cognitive and sociocultural perspectives to provide a comprehensive treatment and diagnostic framework.

### IB Psychology ERQ Assessment Criteria (22 Marks)

#### Criterion A: Focus on the question (2 marks)
- **2 marks**: The essay is focused on the prompt throughout, clearly identifying and discussing biological explanations (such as genetics or neurotransmission) of one specific psychological disorder (such as MDD).
- **1 mark**: The response is somewhat focused on the prompt but contains significant irrelevancy.

#### Criterion B: Knowledge and understanding (6 marks)
- **5-6 marks**: Detailed, accurate, and relevant knowledge of biological explanations (e.g., 5-HTT gene, serotonin hypothesis) and the selected disorder is demonstrated. Key terms are clearly defined.
- **3-4 marks**: Moderate knowledge and understanding are demonstrated, but with some inaccuracies or lack of depth.
- **1-2 marks**: Limited or superficial knowledge and understanding.

#### Criterion C: Use of research (6 marks)
- **5-6 marks**: Relevant psychological research (e.g., Kendler et al., 2006; Caspi et al., 2003) is used effectively to support the explanations. The studies are accurately described (aim, method, findings) and explicitly linked to the essay argument.
- **3-4 marks**: Research is cited but described with some inaccuracies, or the link to the explanation is weak.
- **1-2 marks**: Superficial or descriptive use of research with little relevance.

#### Criterion D: Critical thinking (6 marks)
- **5-6 marks**: The response exhibits well-developed critical evaluation. For example, it discusses treatment-etiology fallacy, reductionism vs. holism, methodological limitations of twin/gene studies, or the Diathesis-Stress model.
- **3-4 marks**: There is some evidence of critical thinking, but it is superficial, generic, or not well integrated.
- **1-2 marks**: Very limited or no critical evaluation is present.

#### Criterion E: Clarity and organisation (2 marks)
- **2 marks**: The essay is well-structured, logical, and easy to follow, with a clear introduction, body paragraphs, and a conclusion.
- **1 mark**: The essay has some structure but lacks overall cohesion or organization.

### Introduction
- **Define the disorder**: Major Depressive Disorder (MDD) is a mood disorder characterized by persistent low mood, anhedonia (loss of interest or pleasure), fatigue, changes in sleep and appetite, and feelings of worthlessness.
- **Introduce biological explanations**: Biological etiologies suggest that MDD is caused by physiological factors. The two primary explanations are:
1. **Genetic vulnerability**: The inheritance of specific genes that make an individual more susceptible to depression.
2. **Neurochemical imbalances (The Serotonin Hypothesis)**: The idea that low levels of serotonin in the synaptic cleft lead to depressive symptoms.
- **Thesis**: While biological factors provide strong, empirical explanations for MDD, they are reductionist when considered in isolation. A holistic model, such as the Diathesis-Stress Model, is necessary to fully explain the onset of the disorder.

### Explanation 1: Genetic Vulnerability
- **Theory**: Genetics suggests that MDD can be inherited through generations. Rather than a single 'depression gene', it is believed to be polygenic, involving multiple genes that interact with environmental factors.
- **Key Study - Kendler et al. (2006)**:
- **Aim**: To investigate the heritability of MDD in a large sample of twins.
- **Method**: Telephone interviews of over 42,000 Swedish twins.
- **Findings**: The researchers found a concordance rate of 42% for female MZ twins and 29% for male MZ twins, compared to 11% and 30% for DZ twins respectively. Overall heritability was estimated at around 38%.
- **Conclusion**: MDD is moderately heritable, with a higher genetic predisposition in females than males.
- **Evaluation of Genetic Explanation**:
- *Strengths*: Large sample size increases generalizability; twin studies control for many confounding variables.
- *Limitations*: Concordance rates are not 100%, indicating that genetics alone cannot explain the disorder. Environmental factors must play a role.

### Explanation 2: Gene-Environment Interaction (GxE)
- **Theory**: The serotonin transporter gene (5-HTT) is responsible for the reuptake of serotonin. A mutation in this gene (short alleles versus long alleles) affects how individuals handle stress.
- **Key Study - Caspi et al. (2003)**:
- **Aim**: To investigate whether a mutation in the 5-HTT gene combined with stressful life events increases the risk of depression.
- **Method**: Longitudinal study of 847 New Zealand participants. Group 1 had two short alleles; Group 2 had one short and one long allele; Group 3 had two long alleles.
- **Findings**: Participants with one or two short alleles who experienced multiple stressful life events were significantly more likely to develop depression than those with two long alleles.
- **Conclusion**: Genetics (5-HTT) interacts with environmental stress to trigger depression, supporting the Diathesis-Stress Model.
- **Evaluation of Caspi et al. (2003)**:
- *Strengths*: Highly longitudinal, naturalistic setting.
- *Limitations*: Self-reported stressful life events may be subject to memory bias. Some replication studies have failed to find the same strong association, suggesting a complex pathway.

### Explanation 3: Neurochemical Explanation (The Serotonin Hypothesis)
- **Theory**: Serotonin is a neurotransmitter involved in mood regulation. Low levels of serotonin or a lack of sensitivity in post-synaptic receptors are hypothesized to cause MDD.
- **Key Evidence**: The success of Selective Serotonin Reuptake Inhibitors (SSRIs) like Prozac, which block the reuptake of serotonin, leaving more in the synaptic cleft and easing depressive symptoms.
- **Evaluation of Neurochemical Explanation**:
- *Strengths*: Practical application in pharmaceutical treatments, which have helped millions of patients worldwide.
- *Limitations*: Treatment etiology fallacy (just because SSRIs alleviate symptoms does not mean a lack of serotonin caused the disorder in the first place). There is a 'therapeutic delay' (SSRI chemical changes occur within hours, but psychological improvement takes weeks), suggesting downstream neurogenesis or cognitive changes are required.

### Critical Discussion & Synthesis
- **Reductionism vs. Holism**: Purely biological explanations are reductionist because they reduce complex human behaviors to neurotransmitters and DNA, ignoring cognitive distortions (Beck's triad) and sociocultural stressors (poverty, relationship breakdowns).
- **Biopsychosocial Approach**: The Diathesis-Stress Model offers a more robust framework. Biology provides the vulnerability (diathesis), but environmental stressors (sociocultural) and negative schema (cognitive) trigger the actual onset of depression.
- **Ethical Considerations**: Genetic determinism may lead to self-fulfilling prophecies or genetic stigmatization.

### Conclusion
- Summarize that biological explanations (genetics, 5-HTT gene, serotonin hypothesis) provide essential insights into MDD.
- Emphasize that because biological mechanisms cannot fully account for the disorder on their own, they must be integrated with cognitive and sociocultural perspectives to provide a comprehensive treatment and diagnostic framework.

### IB Psychology ERQ Assessment Criteria (22 Marks)

#### Criterion A: Focus on the question (2 marks)
- **2 marks**: The essay is focused on the prompt throughout, clearly identifying and discussing biological explanations (such as genetics or neurotransmission) of one specific psychological disorder (such as MDD).
- **1 mark**: The response is somewhat focused on the prompt but contains significant irrelevancy.

#### Criterion B: Knowledge and understanding (6 marks)
- **5-6 marks**: Detailed, accurate, and relevant knowledge of biological explanations (e.g., 5-HTT gene, serotonin hypothesis) and the selected disorder is demonstrated. Key terms are clearly defined.
- **3-4 marks**: Moderate knowledge and understanding are demonstrated, but with some inaccuracies or lack of depth.
- **1-2 marks**: Limited or superficial knowledge and understanding.

#### Criterion C: Use of research (6 marks)
- **5-6 marks**: Relevant psychological research (e.g., Kendler et al., 2006; Caspi et al., 2003) is used effectively to support the explanations. The studies are accurately described (aim, method, findings) and explicitly linked to the essay argument.
- **3-4 marks**: Research is cited but described with some inaccuracies, or the link to the explanation is weak.
- **1-2 marks**: Superficial or descriptive use of research with little relevance.

#### Criterion D: Critical thinking (6 marks)
- **5-6 marks**: The response exhibits well-developed critical evaluation. For example, it discusses treatment-etiology fallacy, reductionism vs. holism, methodological limitations of twin/gene studies, or the Diathesis-Stress model.
- **3-4 marks**: There is some evidence of critical thinking, but it is superficial, generic, or not well integrated.
- **1-2 marks**: Very limited or no critical evaluation is present.

#### Criterion E: Clarity and organisation (2 marks)
- **2 marks**: The essay is well-structured, logical, and easy to follow, with a clear introduction, body paragraphs, and a conclusion.
- **1 mark**: The essay has some structure but lacks overall cohesion or organization.