Investigating retention in LTM
The investigators set out to establish how much information (such as faces and names) graduates could remember many years after graduation.
They traced 392 American high school graduates and tested how well they recalled the names and faces of their class mates.
The study found that the ability to recognise a face or name was remarkably good (90%) for up to 30 years. Not unexpectedly, the ability to recall a name when shown a portrait was less good. However, after 50 years performance on both tests was quite poor, indicating that there might be a general ageing effect.
Bahrick argues that the period from 6 to 35 years represents a ‘permanent memory store’, during which memories are highly resistant to forgetting.
Bahrick’s study makes very effective use of people’s existing memories to assess the duration of LTM. Conducting such a study as an experiment would be impossible for obvious reasons.
However the type of knowledge examined (memory for faces and names) is of a fairly restricted nature and may not represent the duration of LTM in respect of other knowledge. A number of studies have shown that different types of material are forgotten at different rates. For example, Conway et al (1991) surveyed psychology students at the Open University and showed that there were wide differences in the remembering of different topics. Statistical knowledge was the best retained, possibly because this involved procedures and skills rather than just facts.
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