Memory Strategically Encodes Externally Unavailable Information

In the present study, we test the theory that humans selectively encode incoming sensory information on an as-necessary basis, when the information would not be accessible otherwise, in order to compensate for cognitive limitations on the quantity of new information that they can encode. We investigate whether external informational sources—much like high-level knowledge obtained from previous experiences—can spare learners from having to encode all new information in fine-grained detail. If this is true, we would expect to observe differences between the way human learners encode new information that they know to be easily available through external informational resources (e.g., names of actors in a movie, the date of a historical event) and those that they know are not (e.g., names of new acquaintances, the date of a wedding anniversary). Specifically, we would expect learners to encode far less detail for information that is available through known external informational resources than for information that is not. We present evidence from a study run on Amazon Mechanical Turk that human memory preferentially encodes information that is not expected to be available from external informational resources.