For most people, memory is about time. It is easier to remember a set of items in a memory test if they are presented a few seconds before memory retrieval, than if they are presented several hours before. When memory fails, as it does normally in old age, or under pathological conditions such as Alzheimer’s disease, this failure is reflected in the inability to remember over an extended period of time – although the ability to remember over a few seconds may remain intact. Increasingly, however, memory researchers are becoming interested in the ability not to remember over time, but to keep memories distinct and resistant to confusion. If asked to remember where you parked your car this morning, yesterday morning and the day before, the task is difficult not because you need to remember over a long period – you can easily remember many things that happened three days ago – but because the similar memories of your car in that same parking lot are so easily confused. The ability to separate the components of memories into distinct complex memory representations that are unique and less easily confused has been simulated by computational models of memory and has been referred to as ‘pattern separation’. The psychological and neurobiological mechanisms underlying pattern separation are a particular interest of this lab.