Age Differences in the Capacity of Visual Short-term Memory: Effects of Stimulus Type and Information Load

1.40 times) than meaningful items (1.07 times). In Experiment 1, we found an increased information load for abstract items, and greater age differences in information load for abstract items. In Experiment 2, we wanted to see if the pattern of age differences found in visual search would be replicated in a STM task. In other words, would greater age differences in visual search for abstract items be reflected in greater age differences in STM for abstract items? Experiment 2 examined STM accuracy for the same abstract and meaningful items as Experiment 1, and used the same participants. CHAPTER VIII Experiment 2 Experiment 2 assessed the effects of age and item type on STM performance in a Delayed Match to Sample (DMTS) task. Our goals included: 1) comparing age differences in STM accuracy for items from abstract and meaningful classes, 2) comparing intra-class differences in accuracy for items with low, medium, and high load, and 3) comparing subsets of abstract and meaningful items matched for load on accuracy. Though the intention was to analyze matched subsets for both age groups, these subsets of items were matched and analyzed in younger adults only because there were no overlapping subsets of abstract and meaningful items in older adults. The version of the Delayed Match to Sample (DMTS) task used in this experiment is a simple storage task that involves the simultaneous presentation of five stimuli followed by an unfilled delay and a single-item recognition memory test. The dependent variable, proportion correct (accuracy), was used as the measure of STM capacity. In Experiment 2, we first expected to find higher accuracy for meaningful than abstract items. Second, we predicted that younger adults would have higher overall accuracy than older adults. Third, we predicted greater age differences for abstract items. By analyzing a subset of meaningful and abstract items that were matched on information load in younger adults, we also expected to disentangle the contribution of information load and item type tomemory accuracy. We reasoned that if accuracy for abstract items in the matched subset