An industrial psychologist investigates whether upgrading the lighting level in a manufacturing plant increases worker productivity. The psychologist openly measures daily output on the factory floor. Productivity increases by 12% when the lights are made brighter, but also increases by 12% when they are dimmed, and even when they are kept at the baseline level. Once the psychologist leaves the factory floor, productivity returns to normal.
Which methodological phenomenon best explains the workers' temporary increase in productivity?
Demand characteristics
Social desirability bias
Hawthorne effect
Pygmalion effect
644 exam-style questions on OCR A Level Psychology Research methods and techniques. Each one has a worked solution and a mark scheme showing where the marks go.