Learning by Scent Coding

Matthew Stibbe describes an interesting way of coping with exams:

Taking a hint from Proust and his madeleine, when I was at university, I used to smell code my different card decks with aromatherapy oils. Lavender for medieval history, lemon for 19^th century culture and intellect and so on. When I went into each of the seven exams I took in my third year, I’d dab the appropriate smell on my sleeve and the contents of the cards came flooding back. I came across the cards in December when I was unpacking after moving house. The little oil stains were still there but the smell had gone but to this day the scent of lemons gets me thinking about Ruskin, Darwin and William Morris.

Surely this is fairly close to cheating: couldn't the scents be regarded as performance-enhancing drugs? Still, it would be rather hard for the examination boards to ban all perfumes and scents from examination rooms.