The decay characteristics of size, color, and shape information in visual short-term memory

Previous studies of the decay of information in visual short-term memory have made the assumption that all visual properties decay in the same way. The present study challenges this assumption by investigating the individual decay characteristics of size, color, and shape information in visual short-term memory using a partial report method. Twelve observers were shown a display of six objects that were either small or large, red or blue, and a circle or a triangle. After a certain delay period (inter-stimulus interval), observers were cued to report the size, color, or shape of one of the six objects. In experiment one, inter-stimulus intervals (ISIs) ranged from 100 ms to 700 ms; in experiment two, 100 ms to 1900 ms; and in experiment three, 100 ms to 5700 ms. The experimental logic was that a pattern of decreasing accuracy across ISIs reflected a decay of the visual short-term memory representation. In each of the three experiments, unique decay characteristics were found for these three visual properties. Color information showed significant decay between 100 and 700 ms, and then it stabilized and showed no further decay up until an ISI of 5700 ms. Size information showed no decay between 100 and 1900 ms, after which it decayed gradually until the longest ISI of 5700 ms. Shape information gradually decayed after 100 ms across all the ISIs. The discovery of different decay characteristics for size, color, and shape information has implications for how properties are stored in visual short-term memory, as well as how properties are integrated in object representations in visual short-term memory.Arts, Faculty ofPsychology, Department ofGraduat