What is the difference between a single-blind and a double-blind procedure?

In a single-blind procedure, only the participants are unaware of their condition. In a double-blind procedure, both the participants and the researcher are unaware, which controls for both demand characteristics and investigator effects.

How does randomisation differ from standardisation?

Randomisation uses chance to assign participants or order stimuli to prevent researcher bias. Standardisation ensures that the environment and instructions are identical for all participants to maintain consistency.

What is the difference between an extraneous variable and a confounding variable?

An extraneous variable is any 'extra' variable that might affect the DV. A confounding variable is an extraneous variable that changes systematically with the IV, making it impossible to tell which one caused the effect.

What error occurs if a researcher integrates their own expectations into the participant instructions?

This is known as an investigator effect or researcher bias. It threatens internal validity because the participant's behavior may be a response to the researcher's cues rather than the independent variable.

Why is it a mistake to assume that random assignment fixes all research issues?

While random assignment controls for participant variables, it does not prevent issues like demand characteristics, investigator effects, or environmental extraneous variables that occur during the task.

What happens to a study's validity if participants guess the hypothesis?

This triggers demand characteristics, where participants may change their behavior to be 'good' or 'bad' subjects. This results in artificial data that does not reflect natural behavior.

Define 'Demand Characteristics'.

Cues in an experiment that tell the participant what behavior is expected or what the study is about, leading them to change their behavior accordingly.

What is 'Standardisation' in research?

The process of making every aspect of the research procedure identical for all participants, including the script, the room, and the timing, to minimize situational variables.

Define 'Investigator Effects'.

Any effect of the investigator’s behavior or characteristics (conscious or unconscious) on the research outcome or the participants' performance.

Why is a placebo used in clinical research?

A placebo acts as a control for participant expectations. It allows researchers to see if the effect is due to the actual treatment or simply the participant's belief that they are being treated.

Research Issues & Controls | AQA A-Level Psychology

Research Issues & Controls

Summary

Research issues and controls focus on identifying and mitigating extraneous variables that threaten the internal validity of a study. By implementing rigorous techniques such as blinding, randomisation, and standardisation, researchers ensure that changes in the dependent variable are solely attributable to the manipulation of the independent variable.

1. Definition & Core Concepts

Internal Validity: This refers to the extent to which a researcher can confidently state that the observed effect on the dependent variable (DV) was caused by the independent variable (IV) and not by other factors.
Extraneous Variables: These are any variables other than the IV that could potentially influence the results of an experiment, such as participant intelligence or room temperature.
Confounding Variables: A specific type of extraneous variable that varies systematically with the IV, making it impossible to determine which variable caused the change in the DV.

Diagram showing the relationship between Independent, Dependent, and Confounding variables. The confounding variable interferes with the causal link between the IV and DV.

2. Demand Characteristics

Definition: These occur when participants pick up on cues in the research environment that reveal the study's aim, leading them to change their behavior to match (or oppose) expectations.
Participant Reactivity: Participants may act in a way they perceive as 'helpful' (the 'Please-U' effect) or deliberately unhelpful (the 'Screw-U' effect) based on these cues.
Environmental Cues: Factors such as the laboratory setting, the instructions given, or even the researcher's non-verbal communication can trigger these artificial responses.

3. Investigator Effects

Researcher Bias: This involves any influence the researcher has on the outcome, whether conscious or unconscious, through their physical presence or behavior.
Personal Characteristics: Attributes like the researcher's age, gender, ethnicity, or even their tone of voice can unintentionally influence how participants respond to tasks.
Expectancy Effects: If a researcher expects a certain result, they may unconsciously provide subtle cues (e.g., nodding or smiling) when a participant behaves in a way that supports the hypothesis.

4. Control Methodologies

5. Key Distinctions

6. Exam Strategy & Tips