Dad Can Do Time Travel … But Grandpa Can't!

Abstract

Think about what your brain does when you remember. As an experiment, try to remember what you had for lunch yesterday. Maybe it will come to you immediately, but chances are that you will have to think back about where you were when you were eating lunch, whom you were with, what you were talking about or thinking about, and so on. Eventually, the memory of your lunch will reappear! What you have actually done is recalled a specific event – that is, a time, place, and series of sensory experiences – that together constitute a complex memory. We refer to this type of memory as episodic memory, because it represents a specific episode or event in your life. In general, episodic memory refers to memory for events, and you recall them by performing “mental time travel”; that is, thinking back to where you were and what you were doing to recall elements of the event that allow you to retrieve the entire event. In some cases, this might happen without much effort (say, if you saw a really memorable movie) and in other cases it might require more concentration or effort. But this process is the core of what most people mean when they talk about “memory.” There are other types of memory, though. Semantic memory is memory for facts, like the names of objects or your knowing that water boils at 100°C. Procedural memory refers to memory that you may not be consciously aware of, but which you can demonstrate – riding a bike is one example of procedural memory that reflects motor skills.