IB · PSYCH SL

Psychology SL

Research methods — Paper 3 preparation

Name: ____________________Date: October 2, 2026

1.
A researcher investigates whether caffeine improves reaction time by giving one group of participants a caffeinated drink and another group a decaffeinated drink, then measuring reaction time on a computer task. (a) Identify the independent variable and the dependent variable. (b) Explain how the dependent variable has been operationalized in this study.
[3 marks] · no calculator
Marking points
- Identifies the independent variable as whether the drink contains caffeine or not.
- Identifies the dependent variable as reaction time.
- Explains that operationalization means defining an abstract concept (reaction time/alertness) in a specific, measurable way — here, as the time taken to respond on a specific computer task, allowing it to be numerically recorded and compared between groups.
Examiner tip: Operationalization is always about translating an abstract psychological construct into a specific, measurable procedure — always describe exactly how the variable was measured, not just what it conceptually represents.
2.
Marking analysis: A learner attempts the following task: “A researcher investigates whether caffeine improves reaction time by giving one group of participants a caffeinated drink and another group a decaffeinated drink, then measuring reaction time on a computer task. (a) Identify the independent variable and the dependent variable. (b) Explain how the dependent variable has been operationalized in this study.” Their response addresses only this point: “Identifies the independent variable as whether the drink contains caffeine or not.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[3 marks] · no calculator
Marking points
- Recognises credit for the stated point: Identifies the independent variable as whether the drink contains caffeine or not.
- Identifies the missing requirement: Identifies the dependent variable as reaction time.
- Identifies the missing requirement: Explains that operationalization means defining an abstract concept (reaction time/alertness) in a specific, measurable way — here, as the time taken to respond on a specific computer task, allowing it to be numerically recorded and compared between groups.
Examiner tip: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
3.
Distinguish between an independent samples design and a repeated measures design, and state one advantage of a repeated measures design.
[3 marks] · no calculator
Marking points
- Defines an independent samples design as one in which different participants are used in each condition of the experiment.
- Defines a repeated measures design as one in which the same participants take part in every condition of the experiment.
- States a valid advantage of repeated measures, such as controlling for individual differences between participants (since each participant acts as their own control), requiring fewer participants overall.
Examiner tip: Repeated measures controls individual differences but introduces order effects (practice or fatigue) as a new confound — always be ready to name the specific trade-off a design choice introduces.
4.
Marking analysis: A learner attempts the following task: “Distinguish between an independent samples design and a repeated measures design, and state one advantage of a repeated measures design.” Their response addresses only this point: “Defines an independent samples design as one in which different participants are used in each condition of the experiment.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[3 marks] · no calculator
Marking points
- Recognises credit for the stated point: Defines an independent samples design as one in which different participants are used in each condition of the experiment.
- Identifies the missing requirement: Defines a repeated measures design as one in which the same participants take part in every condition of the experiment.
- Identifies the missing requirement: States a valid advantage of repeated measures, such as controlling for individual differences between participants (since each participant acts as their own control), requiring fewer participants overall.
Examiner tip: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
5.
A study finds a strong positive correlation between hours of social media use and reported levels of anxiety. Explain why this correlational finding cannot be used to conclude that social media use causes anxiety.
[3 marks] · no calculator
Marking points
- States that correlation only measures the strength and direction of a relationship between two variables, without manipulating either variable or controlling for confounds.
- Explains that the direction of causality could run the opposite way: anxious individuals might use social media more (e.g., to seek reassurance or distraction), rather than social media causing the anxiety.
- Explains that a third, confounding variable (such as poor sleep, loneliness, or academic stress) could independently cause both increased social media use and increased anxiety, producing the observed correlation without any direct causal link between the two.
Examiner tip: Always offer a concrete example of reverse causality and a concrete example of a third confounding variable — a generic statement that 'correlation does not equal causation' without specific examples rarely earns full marks.
6.
Marking analysis: A learner attempts the following task: “A study finds a strong positive correlation between hours of social media use and reported levels of anxiety. Explain why this correlational finding cannot be used to conclude that social media use causes anxiety.” Their response addresses only this point: “States that correlation only measures the strength and direction of a relationship between two variables, without manipulating either variable or controlling for confounds.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[3 marks] · no calculator
Marking points
- Recognises credit for the stated point: States that correlation only measures the strength and direction of a relationship between two variables, without manipulating either variable or controlling for confounds.
- Identifies the missing requirement: Explains that the direction of causality could run the opposite way: anxious individuals might use social media more (e.g., to seek reassurance or distraction), rather than social media causing the anxiety.
- Identifies the missing requirement: Explains that a third, confounding variable (such as poor sleep, loneliness, or academic stress) could independently cause both increased social media use and increased anxiety, producing the observed correlation without any direct causal link between the two.
Examiner tip: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
7.
State one strength and one limitation of using a case study to investigate a rare psychological phenomenon, such as a specific type of brain damage.
[2 marks] · no calculator
Marking points
- States a valid strength, such as a case study allowing in-depth, detailed study of a rare phenomenon that would be impossible to study with a large sample, often generating rich qualitative data and new hypotheses.
- States a valid limitation, such as findings from a single case being difficult to generalize to the wider population, since the individual's unique characteristics or circumstances may not be representative.
Examiner tip: Case studies trade generalizability for depth — this single trade-off explains almost every strength and limitation commonly cited for this method.
8.
Marking analysis: A learner attempts the following task: “State one strength and one limitation of using a case study to investigate a rare psychological phenomenon, such as a specific type of brain damage.” Their response addresses only this point: “States a valid strength, such as a case study allowing in-depth, detailed study of a rare phenomenon that would be impossible to study with a large sample, often generating rich qualitative data and new hypotheses.” Evaluate the response against the complete 2-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[2 marks] · no calculator
Marking points
- Recognises credit for the stated point: States a valid strength, such as a case study allowing in-depth, detailed study of a rare phenomenon that would be impossible to study with a large sample, often generating rich qualitative data and new hypotheses.
- Identifies the missing requirement: States a valid limitation, such as findings from a single case being difficult to generalize to the wider population, since the individual's unique characteristics or circumstances may not be representative.
Examiner tip: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
9.
A researcher conducts a naturalistic observation of children's play behaviour in a playground, without the children being aware they are being observed. (a) State one strength of this method regarding ecological validity. (b) Explain one way researchers can improve the reliability of observational data when more than one observer is involved.
[2 marks] · no calculator
Marking points
- States that naturalistic observation has high ecological validity, since behaviour is observed in a real, natural setting rather than an artificial laboratory environment, making it more likely to reflect genuine everyday behaviour.
- Explains that researchers can establish inter-observer reliability by having multiple observers independently code the same behaviour using a standardized coding scheme, then statistically comparing their ratings for agreement.
Examiner tip: High inter-observer reliability (strong agreement between independent observers) is the standard way to demonstrate that observational data is not simply reflecting one observer's personal, subjective interpretation.
10.
Marking analysis: A learner attempts the following task: “A researcher conducts a naturalistic observation of children's play behaviour in a playground, without the children being aware they are being observed. (a) State one strength of this method regarding ecological validity. (b) Explain one way researchers can improve the reliability of observational data when more than one observer is involved.” Their response addresses only this point: “States that naturalistic observation has high ecological validity, since behaviour is observed in a real, natural setting rather than an artificial laboratory environment, making it more likely to reflect genuine everyday behaviour.” Evaluate the response against the complete 2-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[2 marks] · no calculator
Marking points
- Recognises credit for the stated point: States that naturalistic observation has high ecological validity, since behaviour is observed in a real, natural setting rather than an artificial laboratory environment, making it more likely to reflect genuine everyday behaviour.
- Identifies the missing requirement: Explains that researchers can establish inter-observer reliability by having multiple observers independently code the same behaviour using a standardized coding scheme, then statistically comparing their ratings for agreement.
Examiner tip: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
11.
Explain why social desirability bias is a particular concern when using self-report questionnaires to measure a sensitive topic, such as alcohol consumption.
[3 marks] · no calculator
Marking points
- Explains that social desirability bias occurs when participants answer in a way they believe will be viewed favourably by others, rather than answering completely honestly.
- Explains that for a sensitive topic like alcohol consumption, participants may systematically under-report their true consumption to avoid appearing irresponsible or to conform to perceived social norms.
- Explains that this systematically biases the collected data toward socially acceptable answers, threatening the validity of the study's conclusions about the true behaviour in the population.
Examiner tip: Social desirability bias is specifically a threat to validity (the data no longer accurately reflects real behaviour), not to reliability (participants might still answer consistently, just consistently inaccurately).
12.
Marking analysis: A learner attempts the following task: “Explain why social desirability bias is a particular concern when using self-report questionnaires to measure a sensitive topic, such as alcohol consumption.” Their response addresses only this point: “Explains that social desirability bias occurs when participants answer in a way they believe will be viewed favourably by others, rather than answering completely honestly.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[3 marks] · no calculator
Marking points
- Recognises credit for the stated point: Explains that social desirability bias occurs when participants answer in a way they believe will be viewed favourably by others, rather than answering completely honestly.
- Identifies the missing requirement: Explains that for a sensitive topic like alcohol consumption, participants may systematically under-report their true consumption to avoid appearing irresponsible or to conform to perceived social norms.
- Identifies the missing requirement: Explains that this systematically biases the collected data toward socially acceptable answers, threatening the validity of the study's conclusions about the true behaviour in the population.
Examiner tip: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
13.
Distinguish between an opportunity sample and a self-selected (volunteer) sample, and explain one way each sampling method could introduce bias into a study's results.
[4 marks] · no calculator
Marking points
- Defines an opportunity sample as one drawn from whoever is conveniently available to the researcher at the time and place of data collection.
- Explains that an opportunity sample can introduce bias because the available population (e.g., people in a specific location at a specific time) may not represent the wider target population.
- Defines a self-selected sample as one in which participants volunteer themselves to take part, typically in response to an advertisement or open call.
- Explains that a self-selected sample can introduce bias because people who volunteer may differ systematically from the general population (e.g., being more motivated, interested in the topic, or having more free time), a problem known as volunteer bias.
Examiner tip: Every sampling method has a characteristic bias tied to how it selects participants — opportunity sampling risks unrepresentative convenience, while self-selection specifically risks an unusually motivated or interested sample.
14.
Marking analysis: A learner attempts the following task: “Distinguish between an opportunity sample and a self-selected (volunteer) sample, and explain one way each sampling method could introduce bias into a study's results.” Their response addresses only this point: “Defines an opportunity sample as one drawn from whoever is conveniently available to the researcher at the time and place of data collection.” Evaluate the response against the complete 4-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[4 marks] · no calculator
Marking points
- Recognises credit for the stated point: Defines an opportunity sample as one drawn from whoever is conveniently available to the researcher at the time and place of data collection.
- Identifies the missing requirement: Explains that an opportunity sample can introduce bias because the available population (e.g., people in a specific location at a specific time) may not represent the wider target population.
- Identifies the missing requirement: Defines a self-selected sample as one in which participants volunteer themselves to take part, typically in response to an advertisement or open call.
- Identifies the missing requirement: Explains that a self-selected sample can introduce bias because people who volunteer may differ systematically from the general population (e.g., being more motivated, interested in the topic, or having more free time), a problem known as volunteer bias.
Examiner tip: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
15.
Distinguish between internal validity and ecological validity in an experimental study.
[2 marks] · no calculator
Marking points
- Defines internal validity as the extent to which a study's results can be confidently attributed to the manipulation of the independent variable, rather than to confounding variables or flaws in the research design.
- Defines ecological validity as the extent to which a study's findings can be generalized to real-world settings and behaviours beyond the specific research context in which they were obtained.
Examiner tip: A tightly controlled laboratory experiment often has high internal validity but lower ecological validity (the artificial setting may not reflect real life) — recognising this common trade-off is central to evaluating any study.
16.
Marking analysis: A learner attempts the following task: “Distinguish between internal validity and ecological validity in an experimental study.” Their response addresses only this point: “Defines internal validity as the extent to which a study's results can be confidently attributed to the manipulation of the independent variable, rather than to confounding variables or flaws in the research design.” Evaluate the response against the complete 2-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[2 marks] · no calculator
Marking points
- Recognises credit for the stated point: Defines internal validity as the extent to which a study's results can be confidently attributed to the manipulation of the independent variable, rather than to confounding variables or flaws in the research design.
- Identifies the missing requirement: Defines ecological validity as the extent to which a study's findings can be generalized to real-world settings and behaviours beyond the specific research context in which they were obtained.
Examiner tip: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
17.
State three ethical considerations a researcher must address when conducting a psychological experiment involving human participants.
[3 marks] · no calculator
Marking points
- States informed consent: participants must be given enough information about the study to decide, before taking part, whether to participate voluntarily.
- States protection from harm: researchers must ensure participants are not exposed to physical or psychological harm beyond what they would experience in ordinary daily life.
- States the right to withdraw (or confidentiality/debriefing) as a third valid ethical consideration, allowing participants to leave the study at any time without penalty, or ensuring their data remains anonymous/confidential.
Examiner tip: The core ethical principles (informed consent, protection from harm, right to withdraw, confidentiality, debriefing) are foundational knowledge expected across every psychology research methods question, not just a dedicated ethics question.
18.
Marking analysis: A learner attempts the following task: “State three ethical considerations a researcher must address when conducting a psychological experiment involving human participants.” Their response addresses only this point: “States informed consent: participants must be given enough information about the study to decide, before taking part, whether to participate voluntarily.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[3 marks] · no calculator
Marking points
- Recognises credit for the stated point: States informed consent: participants must be given enough information about the study to decide, before taking part, whether to participate voluntarily.
- Identifies the missing requirement: States protection from harm: researchers must ensure participants are not exposed to physical or psychological harm beyond what they would experience in ordinary daily life.
- Identifies the missing requirement: States the right to withdraw (or confidentiality/debriefing) as a third valid ethical consideration, allowing participants to leave the study at any time without penalty, or ensuring their data remains anonymous/confidential.
Examiner tip: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
19.
Explain why replication (repeating a study to see if the same results are obtained) is important for the credibility of psychological research findings.
[2 marks] · no calculator
Marking points
- Explains that a single study's findings could be due to chance, a specific unrepresentative sample, or an undetected flaw in the method, rather than reflecting a genuine, reliable psychological effect.
- Explains that successful replication across different researchers, samples, and sometimes cultural contexts increases confidence that the finding reflects a genuine, generalizable psychological phenomenon rather than a one-off result.
Examiner tip: A finding that fails to replicate across multiple independent attempts is a serious warning sign, which is precisely why psychology as a field has placed growing emphasis on large-scale replication studies in recent years.
20.
Marking analysis: A learner attempts the following task: “Explain why replication (repeating a study to see if the same results are obtained) is important for the credibility of psychological research findings.” Their response addresses only this point: “Explains that a single study's findings could be due to chance, a specific unrepresentative sample, or an undetected flaw in the method, rather than reflecting a genuine, reliable psychological effect.” Evaluate the response against the complete 2-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[2 marks] · no calculator
Marking points
- Recognises credit for the stated point: Explains that a single study's findings could be due to chance, a specific unrepresentative sample, or an undetected flaw in the method, rather than reflecting a genuine, reliable psychological effect.
- Identifies the missing requirement: Explains that successful replication across different researchers, samples, and sometimes cultural contexts increases confidence that the finding reflects a genuine, generalizable psychological phenomenon rather than a one-off result.
Examiner tip: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
21.
Distinguish between quantitative and qualitative data, and state one strength of qualitative data.
[3 marks] · no calculator
Marking points
- States that quantitative data are numerical and can be statistically analysed.
- States that qualitative data are descriptive (words, meanings, experiences).
- States a strength of qualitative data, such as greater depth and insight into participants' perspectives.
Examiner tip: Neither type is better; each answers different research questions.
22.
Marking analysis: A learner attempts the following task: “Distinguish between quantitative and qualitative data, and state one strength of qualitative data.” Their response addresses only this point: “States that quantitative data are numerical and can be statistically analysed.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[3 marks] · no calculator
Marking points
- Recognises credit for the stated point: States that quantitative data are numerical and can be statistically analysed.
- Identifies the missing requirement: States that qualitative data are descriptive (words, meanings, experiences).
- Identifies the missing requirement: States a strength of qualitative data, such as greater depth and insight into participants' perspectives.
Examiner tip: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
23.
Explain how triangulation can increase the credibility of qualitative research.
[3 marks] · no calculator
Marking points
- Defines triangulation as using multiple methods, sources, researchers or theories to study the same question.
- Explains that if different approaches lead to similar conclusions, confidence that the findings are not an artefact of one method increases.
- Gives an example, such as combining interviews with observation.
Examiner tip: Credibility is the qualitative counterpart of validity; triangulation is a main way to support it.
24.
Marking analysis: A learner attempts the following task: “Explain how triangulation can increase the credibility of qualitative research.” Their response addresses only this point: “Defines triangulation as using multiple methods, sources, researchers or theories to study the same question.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[3 marks] · no calculator
Marking points
- Recognises credit for the stated point: Defines triangulation as using multiple methods, sources, researchers or theories to study the same question.
- Identifies the missing requirement: Explains that if different approaches lead to similar conclusions, confidence that the findings are not an artefact of one method increases.
- Identifies the missing requirement: Gives an example, such as combining interviews with observation.
Examiner tip: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
25.
Explain what is meant by demand characteristics and how a single-blind design can reduce them.
[3 marks] · no calculator
Marking points
- Defines demand characteristics as cues that lead participants to guess the aim and change their behaviour accordingly.
- Explains that a single-blind design keeps participants unaware of which condition they are in or the true aim.
- Explains that this reduces the chance behaviour is shaped by expectations, improving internal validity.
Examiner tip: Demand characteristics threaten validity because behaviour reflects what participants think is wanted.
26.
Marking analysis: A learner attempts the following task: “Explain what is meant by demand characteristics and how a single-blind design can reduce them.” Their response addresses only this point: “Defines demand characteristics as cues that lead participants to guess the aim and change their behaviour accordingly.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[3 marks] · no calculator
Marking points
- Recognises credit for the stated point: Defines demand characteristics as cues that lead participants to guess the aim and change their behaviour accordingly.
- Identifies the missing requirement: Explains that a single-blind design keeps participants unaware of which condition they are in or the true aim.
- Identifies the missing requirement: Explains that this reduces the chance behaviour is shaped by expectations, improving internal validity.
Examiner tip: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
27.
Explain what is meant by generalizability and one way a researcher can increase it.
[3 marks] · no calculator
Marking points
- Defines generalizability as the extent to which findings from a sample apply to the wider population or other settings.
- Explains a way to increase it, such as using a larger, more representative sample (e.g. random sampling across groups).
- Notes that an unrepresentative sample limits how far conclusions can be applied.
Examiner tip: Generalizability depends on the sample's representativeness as much as its size.
28.
Marking analysis: A learner attempts the following task: “Explain what is meant by generalizability and one way a researcher can increase it.” Their response addresses only this point: “Defines generalizability as the extent to which findings from a sample apply to the wider population or other settings.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[3 marks] · no calculator
Marking points
- Recognises credit for the stated point: Defines generalizability as the extent to which findings from a sample apply to the wider population or other settings.
- Identifies the missing requirement: Explains a way to increase it, such as using a larger, more representative sample (e.g. random sampling across groups).
- Identifies the missing requirement: Notes that an unrepresentative sample limits how far conclusions can be applied.
Examiner tip: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
29.
Explain why debriefing is an important ethical practice after a study involving deception.
[3 marks] · no calculator
Marking points
- Explains that debriefing reveals the true aim and the reason for deception so participants understand what happened.
- Explains that it allows researchers to check for and reduce distress or harm caused by the procedure.
- Explains that participants can ask questions and withdraw their data, restoring autonomy.
Examiner tip: Deception is only acceptable if justified and followed by a full debrief.
30.
Marking analysis: A learner attempts the following task: “Explain why debriefing is an important ethical practice after a study involving deception.” Their response addresses only this point: “Explains that debriefing reveals the true aim and the reason for deception so participants understand what happened.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[3 marks] · no calculator
Marking points
- Recognises credit for the stated point: Explains that debriefing reveals the true aim and the reason for deception so participants understand what happened.
- Identifies the missing requirement: Explains that it allows researchers to check for and reduce distress or harm caused by the procedure.
- Identifies the missing requirement: Explains that participants can ask questions and withdraw their data, restoring autonomy.
Examiner tip: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.