The study by Canli et al. (brain scans and emotions) raised ethical issues of 'right to withdraw' and 'protection from harm'.

Mark scheme

Marking points from the official mark scheme (May/June 2021). The mark or mark type is shown in brackets.

1. [1] 1 mark for description + 1 mark for link x2
2. [1] Right to withdraw: participants can leave a study at any time; for example if they are uncomfortable or distressed; and remove their data; without loss of payment; they should not be pressurised to continue;
3. [1] Right to withdraw may not be apparent if the participant is unaware that they are participating; and may suffer harm as a consequence;
4. [1] Canli et al.'s participants could not easily withdraw from the fMRI machine (as they are hard to get out of, e.g. if they became claustrophobic / because their heads were held still by the bite bar); (link)
5. [2] They were in a scanner; so couldn't leave if they wanted; = 2
6. [1] Protection from harm: a participant should not be exposed to any greater physical or psychological risk than would be expected in their day-to-day life;
7. [1] Canli et al. used an fMRI machine which carries risks for people whose bodies contain metal objects (and a participant might not have known this, so have been at risk);
8. [1] Canli et al. (deliberately) exposed participants to negative images, (which may have been distressing); (link)
9. [1] Canli et al. (apparently) did not use positive images afterwards to reverse the potential mood change; (link)
10. [2] They saw scary/unpleasant images; which could have cause harm; = 2