Which two variables were negatively correlated in Maguire et al.'s (2000) study of taxi drivers' brains?
volume of grey matter in the posterior hippocampus and length of time as a taxi driver
volume of grey matter in the anterior hippocampus and length of time as a taxi driver
volume of grey matter in the anterior hippocampus and age of the taxi drivers
volume of grey matter in the posterior hippocampus and volume of grey matter in the anterior hippocampus