“…For example, for an older person going to the shop, keeping in mind the route and the shopping list, while not being distracted by people and events occurring along the way, is a fundamental means of 'training' the brain, which is presumably performed several times a week. The difficulty of this environmental training depends on where the person lives, and possibly the time of the day and means of transport chosen to reach their destination -an issue explored for example in occupational therapy to maximise opportunities for independent living (Broome et al, 2009;Di Stefano and MacDonald, 2003). Similarly, while the effects of dual tasking in ageing have been extensively documented experimentally (Donoghue et al, 2013;Jain and Kar, 2014;Lindenberger et al, 2000), it is intuitive that crossing a busy road is a challenging form of multi-tasking, especially considering that older people may have slower walking speed, which makes the task difficult even in the absence of distractors (Romero-Ortuno et al, 2010).…”