Aging and repetition priming for targets and distracters in a working memory task

Abstract

A combined working memory/repetition priming task was administered to 13 young (mean age 23) and 13 elderly (mean age 69) adults. Each participant memorized a sample target face at the beginning of a trial and then determined whether each of 13 serially presented test faces matched the sample target. In each trial, both the target and one particular distracter face were repeated during the test phase. Within-trial repetition priming effects indicated the contribution of implicit memory to task performance. Response times decreased as items were tested repeatedly within a trial, but this decrement was greater for distracters than for targets. Young and older participants were equally accurate at identifying targets, but elderly were slightly less accurate for distracters. Elderly participants showed repetition priming effects for both targets and distracters, while the young showed such effects only for distracters. The results suggest that active maintenance in working memory, but not inhibition or rejection of distracters, may suppress implicit memory systems.

Figure 1. Task Schematic

Task schematic of a single trial. Participants viewed a sample target face (outlined in black here) on each trial for 3.76 seconds, followed by a stream of 13 test faces that appeared for 1.88 seconds each. Target faces appeared in this stream of test faces between one and five times (three target repetitions are shown here). A single distracter face also appeared multiple times in each stream of test faces (three repetitions of the first distracter are shown here). All other distracters appeared only once per trial. Participants classified each test face as either a target or distracter by pushing one of two buttons on a button box.

Figure 2. Accuracy for Repetitions of Items Within a Trial

Accuracy of manual responses for repeated targets and distracters only, collapsing across all repetitions within a trial (figure 2a) and as a function of repetitions within a trial (figure 2b).

Figure 3. Response Times for Repetitions of Items Within a Trial

Manual response times for correct responses to repeated targets and distracters only, collapsing across all repetitions within a trial (figure 3a) and as a function of repetitions within a trial (figure 3b).

Figure 4. Response Times for Repetition of Items Across Trials

Individual targets and distracters were used as repeated items in multiple trials to examine behavioral manifestations of the neural reset effect. Manual response times for correct responses to repeated distracters (figure 4a) and targets (figure 4b) only are plotted, showing repetition reductions both within an individual trial and response times in a later trial when that particular item was again repeatedly tested.