RESUMO
Healthy aging is associated with decline in the ability to maintain visual information in working memory (WM). We examined whether this decline can be explained by decreases in the ability to filter distraction during encoding or to ignore distraction during memory maintenance. Distraction consisted of irrelevant objects (Exp. 1) or irrelevant features of an object (Exp. 2). In Experiment 1, participants completed a spatial WM task requiring remembering locations on a grid. During encoding or during maintenance, irrelevant distractor positions were presented. In Experiment 2, participants encoded either single-feature (colors or orientations) or multifeature objects (colored triangles) and later reproduced one of these features using a continuous scale. In multifeature blocks, a precue appeared before encoding or a retrocue appeared during memory maintenance indicating with 100% certainty to the to-be-tested feature, thereby enabling filtering and ignoring of the irrelevant (not-cued) feature, respectively. There were no age-related deficits in the efficiency of filtering and ignoring distractor objects (Exp. 1) and of filtering irrelevant features (Exp. 2). Both younger and older adults could not ignore irrelevant features when cued with a retrocue. Overall, our results provide no evidence for an aging deficit in using attention to manage visual WM.
RESUMO
The present study investigated whether choices between contingencies of variation are affected by the degree of variability required. For such, five pigeons were exposed to a concurrent chain schedule. In the initial links, responses in one key initiated the terminal link with the most stringent variation requirement while responses in the other key initiated the terminal link with the least stringent variation requirement. In both terminal links, four-responses sequences were reinforced according to a variation criterion, which favored less frequent and less recent sequences. The probability of reinforcement in the terminal link with the least stringent criterion was manipulated in order to generate similar percentage and rate of reinforcers in both terminal links. Choices for the terminal link with the least stringent criterion were more frequent than choices for the terminal link with the most stringent criterion. It is possible that situations that demand lower levels of behavior variability are chosen due to the lower response cost correlated to those situations.