This article applies to:
Experiment Author: Susan Campbell. Adapted from STEP and used with permission of Brian MacWhinney
The top experiment shows 1-6 digits and then a probe that may or may not have been in the list. The second experiment shows 2 or 4 digits, then a probe.
This should show that scanning through digits in memory is a serial process that takes a certain amount of time per digit. Even if the digit is present, however, it takes almost exactly the same time it would take if the digit were not present, suggesting that the search is exhaustive rather than terminating.
In this experiment a list of digits between 1-6 numbers appears, followed by a tone. After the tone, another digit appears in red. Determine whether the digit in red at the end was presented in the list before it as quickly and accurately as possible. Respond with the "1" key for Yes and the "2" key for No. This experiment has 36 trials.
There are two versions of this experiment. Version 2 has feedback at the end of each trial. The experiment structure in E-Studio is also different.
NOTE: Both experiments present the Instructions TextDisplay with a specified Duration. In the event the Instructions display too quickly, you may change the Duration to Infinite and add an InputMask.
Sternberg, S. (1966). High speed scanning in human memory. Science 153, 652-654.
Cited Experiment Abstract
When subjects judge whether a test symbol is contained in a short memorized sequence of symbols, their mean reaction-time increases linearly with the length of the sequence. The linearity and slope of the function imply the existence of an internal serial-comparison process whose average rate is between 25 and 30 symbols per second.