Abstract
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. ISIs ranged from 100 ms to 5700 ms over a series of three experiments. The experimental logic was that decreases in accuracy with increasing ISIs reflected decay of the visual short-term memory representation. In each of the three experiments, unique decay characteristics were found for the properties of size, color, and shape. Color information showed significant decay between 100 and 700 ms, and then it stabilized and showed no further decay up until the longest ISI of 5700 ms. Size information showed no decay between 100 and 1900 ms, after which it decayed gradually until an 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 to form object representations.