The effects of the variation in emphasis on speed and accuracy on short term memory (STM) scanning, as measured by reaction time (RT)



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This experiment was conducted to determine the effects of the variation in emphasis on speed and accuracy on item-recognition in Short Term Memory (STM), as measured by Reaction Time (RT). From this measure, inferences are made as to whether STM-scanning is serial and exhaustive, or serial and self-terminating, or parallel. Sternberg's varied-set procedure is largely replicated. Results show STM-scanning to be parallel when speed is highly rewarded and inaccuracy moderately penalized. The first quarter of the serial-presentation trials in the experimental condition without the advantage of practice show relatively higher RTs when compared to the same memory set-sizes in later serial-presentation position trials. This, and not serial and exhaustive STM-scanning, and the position in the memory set the positive test digits are obtained are factors influencing the speed of subjects' execution of the motor responses. Differences in time of STM-scanning or comparison are due to the inherent differences in the number of stages or points required in STM-scanning between set-size 1, set-size 2 to 5, and set-size 6, and not because STM-scanning is serial and exhaustive. A model of STM-scanning has been proposed on the basis of the present findings. This model illustrates STM-scanning as parallel and the fact that the differences in mean RTs of set-size 2 to 5 of the present experiment have been shown to be due to factors other than memory comparison.