One topic of interest to cognitive psychologists is how information is stored and retrieved from short-term memory. In the 1960s, there were two competing types of models: parallel models, in which all information could be retrieved from short-term memory at once, and serial models, in which information was retrieved item by item. In order to determine which model was correct, Sternberg (1966) conducted a series of experiments using a methodology that is replicated in this Sternberg Search experiment. In this experiment, you will be shown a set of digits of one of three sizes (set size condition; 1 digit, 3 digits, or 5 digits) and will be given some time to commit them to short-term memory. There will then be a delay and you will be shown a probe item and will be asked whether the probe item was in the series (probe present/absent condition). Parallel and serial models of retrieval make different predictions about your response times in the different set sizes and probe present/absent conditions. Parallel models predict that all information is instantly accessible and therefore there should be no effect of set size and no effect of whether the probe was present or absent in the series. Serial models, on the other hand, predict both a set size effect (it will take, on average, longer to search through a larger set of digits to make a response) and an effect of probe present/absent conditions (it should take longer to determine that a probe is absent because you must search through the whole set before you can respond).

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