Aging and Inhibition of Return to Locations and Objects.

Inhibition of return (IOR) is thought to reflect a cognitive mechanism that biases attention from returning to previously engaged items. While models of cognitive aging have proposed deficits within select inhibitory domains, older adults have demonstrated preserved IOR functioning in previous studies. The present study investigated whether inhibition associated with objects shows the same age patterns as inhibition associated with locations. Young adults (18-22 years) and older adults (60-86 years) were tested in two experiments measuring location- and object-based IOR. Using a dynamic paradigm (Experiment 1), both age groups produced significant location-based IOR, but only young adults produced significant object-based IOR, consistent with previous findings. However, with a static paradigm (Experiment 2), young adults and older adults produced both location- and object-based IOR, indicating that object-based IOR is preserved in older adults under some conditions. The findings provide partial support for unique age-related inhibitory patterns associated with attention to objects and locations.

Reflexive orienting in response to short- and long-duration gaze cues in young, young-old, and old-old adults.

Shifting visual focus on the basis of the perceived gaze direction of another person is one form of joint attention. In the present study, we investigated whether this socially relevant form of orienting is reflexive and whether it is influenced by age. Green and Woldorff (Cognition 122:96-101, 2012) argued that rapid cueing effects (i.e., faster responses to validly than to invalidly cued targets) were limited to conditions in which a cue overlapped in time with a target. They attributed slower responses following invalid cues to the time needed to resolve the incongruent spatial information provided by the concurrently presented cue and target. In the present study, we examined the orienting responses of young (18-31 years), young-old (60-74 years), and old-old (75-91 years) adults following uninformative central gaze cues that overlapped in time with the target (Exp. 1) or that were removed prior to target presentation (Exp. 2). When the cue and target overlapped, all three groups localized validly cued targets more quickly than invalidly cued targets, and validity effects emerged earlier for the two younger groups (at 100 ms post-cue-onset) than for the old-old group (at 300 ms post-cue-onset). With a short-duration cue (Exp. 2), validity effects developed rapidly (by 100 ms) for all three groups, suggesting that validity effects resulted from reflexive orienting based on the gaze cue information rather than from cue-target conflict. Thus, although old-old adults may be slow to disengage from persistent gaze cues, attention continues to be reflexively guided by gaze cues late in life.

Common-sense beliefs about the prevention of Alzheimer's disease.

OBJECTIVES: Common-sense illness beliefs are important because they influence actions that people take to prevent and treat disease. This research (1) asked younger and older adults about their illness representations of Alzheimer's disease (AD) and (2) manipulated beliefs about AD preventability to determine causal relationships in the data. METHOD: In Study 1, the beliefs of younger (age 18-38; n = 82) and older (age 58-89; n = 57) adults about the causes of and ways to prevent AD were compared. In Study 2, younger adults were randomly assigned to read information stating either that AD can be prevented or not. RESULTS: Compared to younger adults, older adults saw themselves as less at risk, t(137) = 3.03, p = 0.003, d = 0.52, were more likely to believe that AD is preventable, t(137) = 5.01, p < 0.001, d = 0.87 and were more likely to report engaging in behaviors to prevent AD, χ(2)(1, 139) = 19.01, p < 0.001, r = 0.37. Manipulating beliefs in Study 2 caused those told that AD was preventable to see themselves as less at risk, report more prevention behaviors, and hold those with the disease more responsible for their fate. CONCLUSION: These findings highlight the association of illness representations with reports of behavior and show a disconnect between beliefs and what we currently know about AD.

Timing of reflexive visuospatial orienting in young, young-old, and old-old adults.

This study examined adult age differences in reflexive orienting to two types of uninformative spatial cues: central arrows and peripheral onsets. In two experiments using a Posner cuing task, young adults (ages 18-28 years), young-old adults (60-74 years), and old-old adults (75-92 years) responded to targets that were preceded 100-1,000 ms earlier by a central arrow or a peripheral abrupt onset. In Experiment 1, the cue remained present upon target onset. Facilitation effects at short cue-target stimulus onset asynchronies (SOAs) were prolonged in duration for the two older groups relative to the young adults. At longer cue-target SOAs, inhibition of return (IOR) that was initiated by peripheral onset cues was observed in the performance of young adults but not in that of the two older groups. In Experiment 2, the cue was presented briefly and removed prior to target onset. The change in cue duration minimized age differences (particularly for young-old adults) in facilitation effects and led to IOR for all three age groups. The findings are consistent with the idea that attentional control settings change with age, with higher settings for older adults leading to delayed disengagement from spatial cues.

Spatial distribution of attentional inhibition is not altered in healthy aging.

Inhibition of return (IOR) is a phenomenon of attentional orienting that is indexed by slower responses to targets presented at previously attended locations. The purpose of this study was to examine adult age differences in the distribution of IOR to multiple locations. In three experiments, young adults (ages 18-30 years) and older adults (ages 60-87 years) completed an IOR task that varied in the number of simultaneous onset cues (one to seven) and the number of display locations (four or eight). Analyses were conducted to explore whether IOR patterns were most consistent with limited inhibitory resources, with regional distribution of inhibition, or with vector averaging of cues. The IOR effects were most consistent with vector averaging, such that multiple cues initiated a directional gradient of inhibition centered on the average direction of the cues. The IOR patterns varied minimally with age, consistent with the conclusion that older adults and young adults distributed inhibition in a similar manner.

Adult age differences in attention to semantic context.

In three experiments age differences in attention to semantic context were examined. The performance of younger adults (ages 18-29 years) and older adults (ages 60-79 years) on a semantic priming task indicated that both age groups could use information regarding the probability that a prime and target would be related to flexibly anticipate the target category given the prime word (Experiment 1). The timing by which target expectancies were reflected in reaction time performance was delayed for older adults as compared to younger adults, but only when the target was expected to be semantically unrelated to the prime word (Experiment 2). When the target and prime were expected to be semantically related, the time course of priming effects was similar for younger and older adults (Experiment 3). Together the findings indicate that older adults are able to use semantic context and the probability of stimulus relatedness to anticipate target information. Although aging may be associated with a delay in the timing by which controlled expectancies are expressed, these findings argue against an age-related decline in the ability to represent contextual information.

The emotional blink: adult age differences in visual attention to emotional information.

To assess age differences in attention-emotion interactions, the authors asked young adults (ages 18-33 years) and older adults (ages 60-80 years) to identify target words in a rapid serial visual presentation (RSVP) task. The second of two target words was neutral or emotional in content (positive in Experiment 1, negative in Experiment 2). In general, the ability to identify targets from a word stream declined with age. Age differences specific to the attentional blink were greatly reduced when baseline detection accuracy was equated between groups. With regard to emotion effects, older adults showed enhanced identification of both positive and negative words relative to neutral words, whereas young adults showed enhanced identification of positive words and reduced identification of negative words. Together these findings suggest that the nature of attention-emotion interactions changes with age, but there was little support for a motivational shift consistent with emotional regulation goals at an early stage of cognitive processing.

Aging and temporal patterns of inhibition of return.

Inhibition of return (IOR), an inhibitory component of spatial attention that is thought to bias visual search toward novel locations, is considered relatively well preserved with normal aging. We conducted two experiments to assess age-related changes in the temporal pattern of IOR. Inhibitory effects, which were strongly reflected in the performance of both younger adults (ages 18-34 years) and older adults (ages 60-79 years), diminished over a period of 5 s. The time point at which IOR began to diminish was delayed by approximately 1 s for older adults compared with younger adults; this pattern was observed on both a target detection task (Experiment 1) and a color discrimination task (Experiment 2). The finding that timing characteristics of IOR are altered by normal aging has potential implications for the manner in which inhibition aids search performance.

Interrater and test-retest reliability of a fixed condition design fluency test.

Despite its potential as a unique neuropsychological test, the emergence of a psychometrically sound research foundation for Jones-Gotman and Milner's (1977) Design Fluency Test (DFT) has been constrained by the lack of consistent administration and scoring practices and limited information about its reliability. Here we describe an approach to administering and scoring the fixed condition DFT that is modeled on Jones-Gotman and Milner's original method and that clarifies procedural ambiguities. Results include interrater and long-term test-retest reliability analyses using this approach. First, based on five raters who scored 50 DFT protocols, good to excellent intra-class correlation coefficients were obtained for all DFT scores. Second, in a broadly representative sample of 87 healthy adults who were tested twice over an average of 5 1/2 years, the test-retest reliabilities for total and novel design scores ranged from good to excellent. This study demonstrates that the fixed condition DFT can be scored reliably using these procedures and that the reliability coefficients for DFT total and novel designs scores are comparable to those of other commonly used neuropsychological tests.

Differential age effects on attention-based inhibition: inhibitory tagging and inhibition of return.

The purpose of this study was to determine whether 2 forms of attentional inhibition, inhibition of return (IOR) and inhibitory tagging, are differentially affected by the aging process. The authors tested 24 younger adults (mean age = 22 years) and 24 older adults (mean age = 69 years) on a combined IOR and Stroop task (Vivas & Fuentes, 2001). As predicted, younger adults' performance was consistent with inhibitory tagging of objects at inhibited locations. Although older adults demonstrated intact IOR, there was no evidence of inhibitory tagging. The results suggest that age deficits in inhibition are selective.

Lexical and sublexical components of age-related changes in neural activation during visual word identification.

Positron emission tomography data (Madden, Langley, et al., 2002) were analyzed to investigate adult age differences in the relation between neural activation and the lexical (word frequency) and sublexical (word length) components of visual word identification. The differential influence of these components on reaction time (RT) for word/nonword discrimination (lexical decision) was generally similar for the two age groups, with word frequency accounting for a greater proportion of lexical decision RT variance relative to word length. The influence of word length on RT, however, was relatively greater for older adults. Activation in regions of the ventral occipito-temporal cortex was related to the RT changes associated with word frequency and length for older adults, but not for younger adults. Specifically, older adults' frequency effects were related to activation in both anterior (Brodmann's area [BA] 37) and posterior (BAs 17 and 18) regions of the occipito-temporal pathway, whereas word length effects were only associated with posterior activation (BA 17). We conclude that aging affects the neural mechanisms supporting word identification performance although behavioral measures of this ability are generally constant as a function of age.

Age-related changes in selective attention and perceptual load during visual search.

Three visual search experiments were conducted to test the hypothesis that age differences in selective attention vary as a function of perceptual load (E. A. Maylor & N. Lavie, 1998). Under resource-limited conditions (Experiments 1 and 2), the distraction from irrelevant display items generally decreased as display size (perceptual load) increased. This perceptual load effect was similar for younger and older adults, contrary to the findings of Maylor and Lavie. Distraction at low perceptual loads appeared to reflect both general and specific inhibitory mechanisms. Under more data-limited conditions (Experiment 3), an age-related decline in selective attention was evident, but the age difference was not attributable to capacity limitations as predicted by the perceptual load theory.

Adult age differences in visual word identification: functional neuroanatomy by positron emission tomography.

Adult age differences in the neural systems mediating semantic (context-independent) memory were investigated using positron emission tomography (PET). Younger (20-29 years) and older (62-70 years) participants performed lexical decision (word/nonword discrimination) and nonsemantic (simple visual search) baseline tasks during PET scanning. Within the lexical decision task, display duration and presentation rate were varied across scans. The behavioral data suggested that although an age-related slowing was evident in visual feature and response processing, the retrieval of semantic/lexical information was similar for younger and older adults. For both age groups, lexical-related activation occurred in inferior prefrontal and occipitotemporal regions of the left hemisphere. Differential activation, as a function of age group, was observed in the left occipitotemporal pathway as a result of older adults' maintaining higher levels of neural activity in striate cortex (during visual search) and in inferior temporal cortex (during lexical decision). The prefrontal activation was similar for the two age groups. Thus, although this form of semantic memory retrieval does not undergo significant age-related decline, an age-related change in the associated pattern of neural activation is evident. These findings differ from previous neuroimaging studies of episodic (context-dependent) memory retrieval, which have suggested that age-related compensatory mechanisms are expressed primarily by greater activation of prefrontal regions for older adults than for younger adults.

Aging and attentional guidance during visual search: functional neuroanatomy by positron emission tomography.

Positron emission tomography (PET) was used to examine adult age differences in neural activation during visual search. Target detection was less accurate for older adults than for younger adults, but both age groups were successful in using color to guide attention to a subset of display items. Increasing perceptual difficulty led to greater activation of occipitotemporal cortex for younger adults than for older adults, apparently as the result of older adults maintaining higher levels of activation within the easier task conditions. The results suggest that compensation for age-related decline in the efficiency of occipitotemporal cortical functioning was implemented by changes in the relative level of activation within this visual processing pathway, rather than by the recruitment of other cortical regions.