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Gesche M. Huebner, Karl R. Gegenfurtner; The efficiency of encoding - how to get most images into visual memory. Journal of Vision 2010;10(7):756. doi: 10.1167/10.7.756.
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© ARVO (1962-2015); The Authors (2016-present)
The ability of humans to extract meaningful visual information from briefly presented images and to remember them is astonishing. But what is the most efficient way of presenting visual information to achieve maximum performance in terms of remembered items? To address these questions we tested participants in a memory task for natural images where we varied the number of items presented simultaneously, the viewing time and the interstimulus interval (ISI). The viewing phase was followed by a test phase consisting of a 2-AFC recognition task of the images. Performance in terms of percentage of correct answers for the various conditions was then converted into capacity estimates, under consideration of the guessing probability and the number of items presented. This capacity estimation was then scaled to a fixed time unit to be able to compare performance under the different conditions. It proved to be more efficient to only show one object per trial very briefly rather than to show more objects simultaneously for a longer time period. In the final version of our experiment, we combined four presentation times (50, 100, 200, 300 ms) and four interstimulus intervals (0, 50, 100, 200 ms) resulting in 16 conditions. Performance increased significantly with longer trial durations from about 55% to 75% correct. Increases in the presentation time had a larger impact than increases in the ISI. Performance in all conditions was above chance level. When considering memory capacity for a given time unit, in all conditions about 1.3 objects were remembered per second. Thus, in terms of efficiency, variations in presentation time and ISI did not matter very much.
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