ABSTRACT
Previous research has observed that the size of age differences in short-term memory (STM) depends on the type of material to be remembered, but has not identified the mechanism underlying this pattern. The current study focused on visual STM and examined the contribution of information load, as estimated by the rate of visual search, to STM for two types of stimuli – meaningful and abstract objects. Results demonstrated higher information load and lower STM for abstract objects. Age differences were greater for abstract than meaningful objects in visual search, but not in STM. Nevertheless, older adults demonstrated a decreased capacity in visual STM for meaningful objects. Furthermore, in support of Salthouse's processing speed theory, controlling for search rates eliminated all differences in STM related to object type and age. The overall pattern of findings suggests that STM for visual objects is dependent upon processing rate, regardless of age or object type.
ACKNOWLEDGEMENTS
The authors gratefully acknowledge William Hall, Nicole Pukay-Martin, and Jasmine Hudepohl for their assistance with programming, data collection, and scoring. Leslie Vaughan is now an Assistant Professor in the Department of Kinesiology, Occupational Therapy Program, University of Wisconsin at Madison. This research was supported in part by the National Institute on Aging Grant (AG10593) awarded to Marilyn Hartman. Portions of these data were presented at the Cognitive Aging Conference (Atlanta, GA, 2006).