The influence of expertise and task factors on age differences in pilot communication.

The influence of expertise and task factors on age differences in a simulated pilot-Air Traffic Control (ATC) communication task was examined. Young, middle-aged, and older pilots and nonpilots listened to ATC messages that described a route through an airspace, during which they referred to a chart of this airspace. Participants read back each message and then answered a probe question about the route. It was found that pilots read back messages more accurately than nonpilots, and younger participants were more accurate than older participants. Age differences were not reduced for pilots. Pilots and younger participants also answered probes more accurately, suggesting that they were better able to interpret the ATC messages in terms of the chart in order to create a situation model of the flight. The findings suggest that expertise benefits occur for adults of all ages. High levels of flying experience among older pilots (as compared with younger pilots) helped to buffer age-related declines in cognitive resources, thus providing evidence for the mediating effects of experience on age differences.

Patterns of resource allocation are reliable among younger and older readers.

Younger and older adults read short expository passages across 2 times of measurement for subsequent comprehension or recall. Regression analysis was used to decompose word-by-word reading times into resources allocated to word- and textbase-level processes. Readers were more sensitive to these demands when reading for recall than when reading for comprehension. Patterns of resource allocation showed good test-retest reliabilities and were predictive of memory performance. Within age group, resource allocation parameters were not systematically correlated with other individual-difference measures, suggesting that strategies of on-line resource allocation may be a unique source of individual differences in determining comprehension of and memory for text. Age differences in allocation patterns appeared to reflect general slowing among the older adults. Because older adults showed equivalent memory performance to that of younger readers, the reading time data may represent the on-line resource allocation needed for comparable outcomes among older and younger readers.

Age differences in on-line syntactic processing.

Reading time and comprehension for subject-relative (e.g., The pilot that admired the nurse dominated the conversation) and object-relative (e.g., The pilot that the nurse admired dominated the conversation) constructions were compared among younger and older readers. Younger adults, but not older adults, differentially allocated time to the more taxing object-relative constructions. Although there were no age differences in comprehension of subject-relative constructions, older adults demonstrated lower levels of comprehension for object-relative sentences. Inconsistent with a modularity view positing preservation in "interpretive" processes with age, these results suggest that age-related differences in working-memory capacity limit responsiveness to text demands, thus compromising sentence comprehension.

The effects of context and feedback on age differences in spoken word recognition.

We investigated the hypothesis that age differences in speech discrimination would be reduced by enhancing the distinctiveness of the speech processing event in terms of both the context of encoding and the response outcome. Younger and older adults performed an auditory lexical decision task in which the degree of semantic constraint (context) and type of feedback were manipulated. Main effects of age indicated that older adults generally showed lower discriminability (D) and greater bias (B) toward reporting signals to be words. Consistent with the environmental support hypothesis, older adults were differentially facilitated in discriminability by feedback, but only when semantic context was provided. Also, for both younger and older adults, feedback and context each had the effect of reducing bias and facilitating the speed of rejecting nonwords. Contrary to one suggestion in the literature that aging brings an insensitivity to environmental contingency, older adults were at least as capable as the young in taking advantage of feedback to normalize the speech signal so as to increase discriminability and decrease bias.

Aging and the effects of knowledge on on-line reading strategies.

The effects of knowledge on on-line reading strategies and the relation of these effects to subsequent memory performance among young and elderly adults were investigated. Participants read passages with vague, ill-defined content word-by-word on a computer screen for immediate recall and reading times were recorded. High-knowledge (HK) readers received passage titles that clarified the content and low-knowledge (LK) readers did not. Reading strategy was found to be related to age, knowledge, and subsequent recall performance. LK readers, particularly those who produced high levels of recall, spent differentially more time at intrasentence and sentence boundaries suggesting that they allocated more processing resources to consolidate the concepts in the seemingly disjointed text. HK readers, on the other hand, showed facilitation in this organizational processing. These beneficial effects were more pronounced for elderly readers than for younger readers, suggesting that older readers take special advantage of knowledge in the on-line processing of discourse. Moreover, older LK readers who were above average in recall were differentially slowed at boundaries showing that successful older readers who lacked a situation model with which to interpret text allocated differentially more time to organize and integrate text than did their younger counterparts.

The role of reader age and focus of attention in creating situation models from narratives.

We examined adult age differences in the mental representation of situations and how readers update this representation during narrative comprehension. Older and younger adults memorized a building layout and then read narratives about a protagonist's actions in this building. The narratives contained critical sentences that described the protagonist moving from one room (the "source room") into another (the "goal room"), through an unmentioned path room. Each critical sentence was followed by a target sentence referring to an object in one of these rooms. Half of the target sentences explicitly mentioned the room containing this object and half did not. Reading time increased when the target object was more distant from the protagonist and when the room containing the object was not mentioned, suggesting that readers tracked the protagonist's location in the layout and allocated resources in order to maintain coherence in the situation model. Older adults' reading times differentially slowed with distance, and older readers who more accurately understood the narrative differentially slowed when the location of the target object was not mentioned. Finally, the more accurate readers (older and younger) slowed primarily when updating was most difficult (i.e., both when the room containing the object was not mentioned and for more distant objects). While these findings reveal qualitative similarity in how older and younger readers update spatially organized situation models, they also suggest that older readers must sometimes allocate more resources to this updating process in order to maintain comprehension.

Medication instruction design: younger and older adult schemas for taking medication.

We examined whether older and younger adults share a schema for taking medication and whether instructions are better recalled when they are organized to match this schema. Experiment 1 examined age difference in schema organization. Participants sorted medication items (e.g., purpose, dose, possible side effects) according to similarity and then ordered the items to create a preferred instruction set. Cluster analysis of the sort and order data showed that younger and older adults share a schema for taking medication. Secondary regression analyses found that verbal ability (i.e., vocabulary scores) predicted individual differences in schema organization. In Experiment 2 participants recalled instructions that were either compatible with this schema in terms of grouping and order of items or were presented in nonpreferred orders. Younger participants remembered more information than did older participants, but both age groups better remembered and preferred the more schema-compatible instructions. Secondary analyses showed that recall was also positively related to verbal ability. Along with our earlier research, this study suggests that older and younger adults possess a schema for taking medication and that instructions that are compatible with this schema provide an environmental support that improves memory for medication information.

Resource allocation in on-line reading by younger and older adults.

Younger and older adults read a series of expository passages for immediate recall by self-pacing the presentation sector-by-sector on a computer screen. Regression analysis of sector reading times (RT) was used to estimate the time allocated by individuals to word-level (i.e., syllable length and mean word frequency), text-level (i.e., number of propositions, number of new concepts introduced, and total Yngve depth), and discourse-level (i.e., serial position) features. Age differences were found in the pattern of reading time allocation that engendered high levels of recall. Specifically, younger adults who achieved high recall were more responsive to word frequency and the introduction of new concepts. By contrast, high recall among the old was related to a greater degree of on-line contextual facilitation (i.e., a steeper serial position effect). These data suggest that there is an age difference in how the allocation of resources at encoding optimizes subsequent memory performance.

Venn diagrams and neuronal vulnerability.

Greenamyre and Young note that there is poor correlation between which hippocampal regions are damaged in Alzheimer's disease and which have the highest concentrations of NMDA receptors. They conclude that EAAs can thus only be necessary, but not sufficient to explain Alzheimer's damage. We note that this is in fact probably the rule rather than the exception: some of the most credible agents which damage neurons are merely necessary, but not sufficient to explain selective neuronal vulnerability.