A psychologist gives adults a five-minute letter-cancellation task. Half of the adults chew one piece of sugar-free gum throughout the task, while the other half complete it without chewing gum. Each adult's score is the number of target letters correctly crossed out from 30.
State the null hypothesis for this investigation.
182 exam-style questions on OCR GCSE Psychology 7.1 Planning Research, covering 7.1.1 Hypotheses, 7.1.2 Variables, 7.1.3 Experimental Designs, 7.1.4 Populations and Sampling, 7.1.5 Ethical issues, and 7.1.6 Dealing with ethical issues and BPS Code. Each one has a worked solution and a mark scheme showing where the marks go.