(First published online 23 March 2016)
doi:https://doi.org/10.1017/S0007114516000337, Published by Cambridge University Press.
Original text and correction
Original text in Fig. 1: n=9 under ‘Food v. no food’ n=7 under ‘Food v. food’.
Correct text: n=12 under ‘Food v. no food’ and n=4 under ‘Food v. food’.