Learning how to exploit sources of information.

How is our strategy for forming memories shaped by experience with a task? Previous work using surprise questions (i.e., unexpected by the participant) has shown a remarkable inability to report attributes of an attended target in a search display. This representational poverty presumably reflects a form of information exploitation, in which control processes specialize the conversion of available information into memory representations. We hypothesize that such control is refined by repeated experience with a task, and as a result, memory representations will specialize as task experience accrues, such that report accuracy for an unexpected question will progressively worsen as the number of preceding trials increases. To test this, subjects were asked to report the location of a letter among three digits. The ability to respond correctly to a surprise question about the identity of that letter became worse as the experiment progressed. A follow-up study evaluated whether this incremental worsening of report accuracy could be explained as a buildup of proactive interference by varying the set of letters for the surprise test. The results were unchanged relative to the original experiment, which argues against a primary contribution of proactive interference in the worsening performance. The effect was replicated in a similar paradigm using color disks. These findings illustrate that repeated performance of a prescriptive task engages an adaptive modification of control processes that focus information processing on specific attributes of a stimulus that are expected to be necessary in the future, regardless of their immediate task relevance.