Selective attention modifies long-latency cortical event-related potentials. Amplitudes are typically enhanced and/or latencies reduced when evoking stimuli are attended. However, there is controversy concerning the effects of selective attention on short-latency brain stem evoked potentials. The objective of the present study was to assess possible attention effects on the brain stem auditory frequency-following response (FFR) elicited by a periodic tone. Young adult subjects heard a repetitive auditory stimulus while detecting infrequent target stimuli in either an auditory or visual detection task. Five channels of high frequency electroencephalographic (EEG) activity were recorded along the scalp midline with the center electrode positioned at the vertex. The FFR was elicited by the repetitive tone during both tasks. There were significant individual differences in the electrode sites yielding maximum response amplitudes, but overall FFR amplitudes were significantly larger during the auditory attention task. These results suggest that selective attention in humans can modify signal processing in sensory (afferent) pathways at the level of the brain stem. This may reflect top-down perceptual preprocessing mediated by extensive descending (efferent) pathways that originate in the cortex. Overall, the FFR appears to be a robust indicator of early auditory neural processing and shows effects not seen in brain stem auditory evoked response studies employing transient (click) acoustic stimuli.

The ability of young (aged 18-30) and older (aged 60-80) adults to discriminate pre-experimental (semantic) from experimental (episodic) associations was examined. Participants studied a list containing semantically related and unrelated word pairs and then made either associative recognition (Experiments 1a and b) or semantic relatedness (Experiment 2) judgments at various response deadlines. For associative recognition judgments, both young and older adults benefited from semantic relatedness, leading to more hits for related than unrelated pairs, and at the long response deadline, older adults' performance on those pairs matched that of young participants. Also, both young and older adults demonstrated superior discrimination for unrelated lures whose members had originally been studied in related pairs - evidence for recall-to-reject processing in both age groups. In making semantic relatedness judgments, both young and older adults showed an episodic priming effect. When older adults can rely on long-standing associations, their performance resembles that of young adults - both in associative recognition and in episodic priming.

These results suggest that older adults have preserved metacognitive abilities with regard to assessing the consequences for accuracy of maintaining a lenient criterion when discrimination between experienced and new information becomes more difficult and further suggests that they can take appropriate action to control error rates under these conditions.

We examined young and older adults' ability to flexibly adapt response criterion on a recognition test when the probability that a test item had been studied was cued by test color. One word color signaled that the probability of the test item being old was 70% and a second color signaled that the probability of the test item being new was 70%. Young and older adults demonstrated similar levels of criterion shifting in response to color cues. Moreover, although both young and older adults were slowed when test-item color incorrectly predicted test-item status, the extent of slowing did not differ across age group. Putative measures of cognitive control predicted recognition accuracy but not the degree to which criterion changed with test-item color. These results suggest that adaptive criterion shifting does not tax cognitive control or, if it does require effort, may be no more onerous for older than for young adults.

The study reported here examined the effect of repetition on age differences in associative recognition using a paradigm designed to encourage recollection at test. Young and older adults studied lists of unrelated word pairs presented one, two, four, or eight times. Test lists contained old (intact) pairs, pairs consisting of old words that had been studied with other partners (rearranged lures), and pairs consisting of two unstudied words (new lures). Participants gave old/new responses and then indicated whether their responses were based on details that they could recollect or on familiarity. Older adults exhibited an ironic effect of repetition-an increase in false alarms on rearranged lures with more study opportunities-whereas young adults did not. Older adults also claimed to recall details of the study episode for rearranged lures whose constituent words were presented more frequently, but this was not true for young adults. Although both young and older adults said that they based correct rejections of rearranged lures on memory for details of the study episode, this effect was stronger for young adults. The observed age differences are consistent with older adults having reduced use of recollection in associative recognition tasks.