The functional interaction of visual-perceptual and response mechanisms during selective attention in young adults, young-old adults, and old-old adults

Evidence that ageing yields improvements as well as declines across attention and executive functions

Many but not all cognitive abilities decline during ageing. Some even improve due to lifelong experience. The critical capacities of attention and executive functions have been widely posited to decline. However, these capacities are composed of multiple components, so multifaceted ageing outcomes might be expected. Indeed, prior findings suggest that whereas certain attention/executive functions clearly decline, others do not, with hints that some might even improve. We tested ageing effects on the alerting, orienting and executive (inhibitory) networks posited by Posner and Petersen's influential theory of attention, in a cross-sectional study of a large sample (N = 702) of participants aged 58-98. Linear and nonlinear analyses revealed that whereas the efficiency of the alerting network decreased with age, orienting and executive inhibitory efficiency increased, at least until the mid-to-late 70s. Sensitivity analyses indicated that the patterns were robust. The results suggest variability in age-related changes across attention/executive functions, with some declining while others improve.

Face naming and retrieval inhibition in old and very old age

BACKGROUND/STUDY CONTEXT: Aging has traditionally been related to impairments in proper name retrieval. This study analyzed the possible role of the Inhibitory Deficit Hypothesis in explaining face naming impairments during aging. The dynamics of inhibition have been thoroughly studied by the retrieval-practice paradigm (Anderson, Bjork, & Bjork, 1994, Journal of Experimental Psychology: Learning, Memory, and Cognition, 20, 1063-1087) and its aftereffect, the retrieval-induced forgetting effect.

METHODS

A version of the retrieval-practice paradigm was employed: younger-old (YO; mean age = 66.40, SD = 3.94) and older-old (OO; mean age = 80.94, SD = 4.53) adults were asked to repeatedly name faces of categorically related famous people.

RESULTS

Retrieval-induced forgetting for names was observed in the YO group but not in the OO group.

CONCLUSION

These findings indicate that whereas the YO adults had enough resources to inhibit intrusive names, OO adults were not able to suppress competing names, supporting the proposal of the Inhibitory Deficit Hypothesis at older ages.

Effects of aging on visual attentional focusing

BACKGROUND

Visual attentional performance is affected by aging, but there are methodological barriers to the understanding of this phenomenon that are due, above all, to the concomitant deterioration of sensory or central factors such as visual acuity and information processing speed.

OBJECTIVE

The aim of the present study was to verify the effects of aging on visual attentional focusing by analyzing the space- and object-based components as well as the exogenous and endogenous dimensions of the attentional allocation.

METHODS

Focusing of visual attention was investigated in 14 youngsters, 14 younger adults and 14 older adults (age ranges 12-15, 24-38 and 60-75 years, respectively). In two discrimination reaction time (RT) experiments, attention was cued by means of spatial cues of different size followed by compound stimuli at a shorter (150 ms) and a longer (500 ms) stimulus-onset asynchrony (SOA). The compound stimuli contained a predefined target letter at a local or global level.

RESULTS

Older adults showed generally slower RTs and higher rates of delayed responses than younger individuals and reduced discrimination speed of local objects at 150-ms SOA, particularly when attention was invalidly cued to focus at a larger spatial scale.

CONCLUSIONS

This pattern of results suggests that aging causes a dysfunction of the space-based and the object-based components of the attentional 'zooming in'. Such information may be of practical relevance for developing attentional training programs for older adults.

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.

'Young old' and 'old old' poor sleepers with and without insomnia complaints

OBJECTIVE

Sleep, psychological adjustment, health and insomnia complaints were examined in 277 community-dwelling seniors in order to identify characteristics that distinguish poor sleepers with complaints (likely to seek treatment) and those without complaints (unlikely to seek treatment).

METHODS

Two weeks of sleep diaries and other sleep-related measures were collected. Young old (65-74 years) and old old (75+) participants were categorized as: good sleepers, poor sleepers with complaints (complainers), and poor sleepers without complaints (noncomplainers).

RESULTS

In both age groups, complainers had poorer sleep than noncomplainers. Complainers also reported more depressive symptoms and had poorer health than noncomplainers. The old old slept longer each night, but took longer to fall asleep, napped more, and were more likely to complain of insomnia than the young old; otherwise, the young old/old old distinction did not explain sleep differences among the three types of sleepers.

CONCLUSIONS

Implications for treating late-life insomnia include greater inclusion of the old old in treatment outcome research and more focus on the development of integrated intervention and prevention strategies that target health, depressive symptoms, and sleep.

Local-global processing in Alzheimer's disease: an examination of interference, inhibition and priming

Impairments of memory, praxis, gnosis, language and executive functioning are well documented in Alzheimer's disease (AD). Functions, such as attention, however, have only recently been systematically investigated. We used Navon-type stimuli (large "global" digits composed of smaller "local" digits) to assess 12 AD participants' plus age-matched controls' ability to focus and alter the scale of their spatial attention. In the first experiment, participants responded to either the global or local characters within a block, ignoring characters at the other spatial scale. Healthy young adults (n=12) demonstrated the normal 'global precedence' effect on this task. In contrast, participants with AD and their age-matched controls were significantly faster on the local task than on the global task, suggesting in these groups a 'local precedence' effect. This consisted of both a local advantage and a local-on-global interference effect. In a second experiment, participants searched for designated targets which occurred unpredictably at either the local or global spatial scale. Participants with AD were significantly slower and more error-prone than older controls. In addition, participants with AD showed a greater cost in reaction time (RT) when required to switch spatial scales on consecutive trials, compared to no switch responses at the same spatial scale on consecutive trials. Thus, AD may impair the ability to process global figures, due perhaps to involvement of posterior parietal areas. Further, participants with AD were poor at inhibiting irrelevant stimuli and at inhibiting attentional allocation to an irrelevant spatial scale, which may relate to prefrontal pathology.

Visual target detection paradigm for the study of selective attention

The current protocol can be used to examine selective attention. It has been used to acquire behavioral performance data in neurologically healthy normal control subjects and schizophrenic patients. A modified version, also described here, has been used to acquire functional neuroimaging data in normal subjects using positron emission tomography. Subject response accuracy and reaction times are recorded while subjects detect visual stimuli in either hemifield (left vs. right of a fixation point) or along the vertical meridian (above or below fixation). The lateralized presentation of stimuli permits the study of hemispheric specialization for selective attentional processes. Attentional load is manipulated by presenting larger-sized target stimuli alone (i.e., the letter 'O') or smaller-sized target stimuli surrounded by flanking letters. This protocol report includes a description of subject exclusion criteria, procedural details, relevant experimental conditions and variables, suggestions for data analysis, expected results, and a discussion of the protocol's significance for attentional research along with suggestions for future research.