The “cone of learning, aka the “learning pyramid” or the “cone of experience” is popular — and unreliable — writes cognitive scientist Dan Willingham in Cone of learning or cone of shame?
Many variables affect memory retrieval:
what material is recalled (gazing out the window of a car is an audiovisual experience just like watching an action movie, but your memory for these two audiovisual experiences will not be equivalent)
the age of the subjects
the delay between study and test (obviously, the percent recalled usually drops with delay)
what were subjects instructed to do as they read, demonstrated, taught, etc. (you can boost memory considerably for a reading task by asking subjects to summarize as they read)
how was memory tested (percent recalled is almost always much higher for recognition tests than recall).
what subjects know about the to-be-remembered material (if you already know something about the subject, memory will be much better.
Taking practice tests and spreading out study sessions is effective, researchers conclude. In Why Don’t Students Like School?, Willingham advises: “Try to think about material at study in the same way that you anticipate that you will need to think about it later.”