 Short term memory holds information for slightly longer periods of time, but still has a limited capacity.According to Linden (2007), "The capacity of STM had initially been estimated at "seven plus or minus two" items (Miller 1956), which fits the observation from neuropsychological testing that the average digit span of healthy adults is about seven (Cowan and others 2005).However, it emerged that these numbers of items can only be retained if they are grouped into so-called chunks, using perceptual or conceptual associations between individual stimuli."