(Image: Darren Hopes)
I鈥橫 NOT a person for a pub quiz team. I can dredge up obscure details from conversations long ago, but I can never remember the heights of the mountains I have climbed or the names of pop bands.
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My colleague Richard is the opposite. He鈥檚 great at remembering facts, but all at sea when it comes to details of his past personal experiences. Should he or I be worried?
Memory is actually mostly about forgetting: all brains discard most of the sensory data they receive. 鈥淭omorrow you鈥檒l remember reasonably well a conversation you had today,鈥� says neurobiologist of the University of California, Irvine. 鈥淲ithin a week, a lot of that information will have been lost.鈥� Within a year, the conversation might be gone entirely.
Direct sensory memories only last a few moments. Some go on to make short-term memories, such as the phone number you just dialled. Exact figures are hard to pin down, but an average brain can , for up to 30 seconds.
Only makes it into long-term memory, such as a conversation that contained a personal insult. 鈥淲e have selectively strong memories for events that are emotionally arousing,鈥� says McGaugh. Long-term memories divide into two main types. Semantic memories record facts, such as the concept of a train. Episodic ones are about events we have experienced, such as a particular train journey.
We probably all know someone who has an encyclopaedic factual memory, but extraordinary episodic memories are a more recent discovery. 鈥淭hese people remember events from years ago the way you and I remember events from last week,鈥� says McGaugh. There鈥檚 also the opposite condition, in which people struggle to recall even recent events they have experienced. 鈥淭hey know the event happened, but they can鈥檛 mentally travel back, even one week,鈥� says , who researches autobiographical memory at Boston University in Massachusetts.
Most of us fall between these two extremes. True to the stereotype, . With semantic memory, , whereas . Personality type seems to be a factor, too: people open to new experiences tend to have better autobiographical memory.
Ageing affects the recall of personal experiences more than that of facts, . But if by our 40s we notice we can鈥檛 remember new names, it鈥檚 not that our brains are overloaded 鈥� our memory capacity is practically unlimited. Rather, gradual changes in brain structure, such as a reduction in the density of dendrites that help to form connections between neurons, .
But until you start finding it difficult to carry out a simple task you have done many times before, or follow the flow of a conversation, you shouldn鈥檛 be overly concerned if your memory seems to move in mysterious ways. Ultimately, memory is a personal thing, says psychologist of Durham University in the UK. 鈥淧eople remember things that are important to them. We all have different interests and this changes what our mind processes,鈥� he says. 鈥淢y wife is interested in flowers. When we visit a garden, I just see a jumble of colours, whereas she will remember all sorts of detail.鈥�
Memories are systems with multiple parts that change over time, so it is unsurprising that there is a lot of variation. 鈥淭here are strong individual differences,鈥� says McGaugh. 鈥淚t鈥檚 a characteristic of human memory that we don鈥檛 all remember the same kind of things.鈥�
Read more: 鈥�Is your mind normal? 7 reasons it probably is鈥�
This article appeared in print under the headline 鈥淚s my memory normal?鈥�
