A sensory origin for color-word stroop effects in aging: simulating age-related changes in color-vision mimics age-related changes in Stroop

An increase in Stroop effects with age can be interpreted as reflecting age-related reductions in selective attention, cognitive slowing, or color-vision. In the present study, 88 younger adults performed a Stroop test with two color-sets, saturated and desaturated, to simulate an age-related decrease in color perception. This color manipulation with younger adults was sufficient to lead to an increase in Stroop effects that mimics age-effects. We conclude that age-related changes in color perception can contribute to the differences in Stroop effects observed in aging. Finally, we suggest that the clinical applications of Stroop take this factor into account.     

Modelling age-related changes in information processing

Researchers in cognitive ageing seldom take advantage of explicit quantitative models of information processing to account for age differences in cognition. Where quantitative models have been used, these models typically remain silent about the details of information processing. The lack of explicit cognitive models has consequences for the interpretation of a number of empirical results. Using a specific class of models called random walk models, I review evidence showing that the empirical relations taken as support for global age-related changes are consistent with a number of possible age effects on information processing. In addition, I demonstrate that these models can be used to account for age differences within the context of individual experiments and such modelling has important implications for the interpretation of age differences in performance.     

Expertise and age-related changes in components of intelligence

In a sample of 263 male GO players at 48 levels of expertise and ranging from 18 to 78 years of age, it was found that factors of expertise deductive reasoning (EDR) and expertise working memory (EWM) were independent of factors of fluid reasoning (Gf) and short-term working memory (STWM) that, along with cognitive speed (Gs), have been found to characterize decline of intelligence in adulthood. The main effects of analyses of cross-sectional age differences indicated age-related decline in EDR and EWM as well as in Gf, STWM, and Gs. However, interaction and partialing analyses indicated that decline in EDR and EWM decreased to no decline with increase in level of expertise. The results thus suggest that with increase in factors known to raise the level of expertise--particularly, intensive, well-designed practice--there may be no age-related decline in the intelligence that is measured in the abilities of expertise.     

Dichotic listening in children: age-related changes in direction and magnitude of ear advantage

Children between the ages of 5 and 12 years were tested with dichotic listening tests utilizing single syllable words and random presentations of digits. They produced a higher prevalence of left ear dominance than expected, especially among right-handed children when tested with words. Whether more children demonstrate the LEA because of right hemisphere dominance for language or because there is less stability in ear advantage direction at younger ages cannot be fully resolved by this study. When ear advantages were measured by subtracting each child's lower score from the higher score without regard to right or left direction, an age-related trend toward lower measures of ear advantage was evident. This trend was greater for dichotic words than for dichotic digits. Structural factors that may be related to these results and possible influences of attention and verbal workload on the two kinds of dichotic stimuli are discussed.     

Progressive age-related changes in the attentional blink paradigm

Previous studies on aging and attention typically examine group differences between younger and older adults, rather than seeing aging as a continuous process. Using correlational analyses, this study examined progressive changes in the magnitude of the attentional blink (AB) associated with aging. Increased age was found to be significantly associated with the ability to detect the second target (T2), whereby older age was correlated with the production of a longer and more pronounced AB; this supports the proposition that aging is associated with reduced inhibitory processes and selective attention. It was also found that AB performance somewhat improves between ages 18-39 years, but tends to decline from 40 years of age onward, providing an interesting and novel finding that AB effects may become more sensitive at this point in time. The AB task may prove useful in the assessment of selective attention in normal healthy adults, as well as changes associated with pathological aging.     

Developing connections for affective regulation: age-related changes in emotional brain connectivity

The regulation of affective arousal is a critical aspect of children’s social and cognitive development. However, few studies have examined the brain mechanisms involved in the development of this aspect of “hot” executive functioning. This process has been conceptualized as involving prefrontal control of the amygdala. Here, using functional magnetic resonance imaging (fMRI), we investigated the brain mechanisms involved in the development of affective regulation in typically developing 5- to 11-year-olds and an adult comparison sample. Children and adults displayed differing patterns of increased anterior cingulate cortex and decreased amygdala activation during episodes in which emotion regulation was required. Specifically, amygdala activation increased in adults but decreased in children during recovery from a frustrating episode. In addition, we used effective connectivity analyses to investigate differential correlations between key emotional brain areas in response to the regulatory task demands. We found reliable increases in effective connectivity between the anterior cingulate cortex and the amygdala during periods of increased demand for emotion regulation. This effective connectivity increased with age.     

Lapses of intention and performance variability reveal age-related increases in fluctuations of executive control

We examine the hypothesis that the efficiency of executive control processes is less stable over time in older than younger adults. An age-related decrease in the efficiency of executive control should result in an increase in performance variability in task conditions requiring the recruitment of executive control processes and not in task conditions requiring minimal involvement of executive control. Performance variability was similar for younger and older adults in task conditions requiring minimal executive control and greater for older than younger adults in task conditions requiring executive control. These and other data are consistent with the proposal that aging is associated with a decrease in the stability of executive control over time.     

Memory retrieval by 18--30-month-olds: age-related changes in representational flexibility

Deferred imitation was used to trace changes in memory retrieval by 18-30-month-olds. In all experiments, an adult demonstrated 2 sets of actions using 2 different sets of stimuli. In Experiments 1A and 1B, independent groups of infants were tested immediately or after a 24-hr delay. Each infant was tested with 1 set of stimuli from the original demonstration and 1 set of stimuli that was different. Recall of the target actions when tested with different stimuli increased as a function of age, particularly after a delay. In Experiment 2, infants were provided with a unique verbal label for the stimuli during the demonstration and the test. The verbal label facilitated performance by 24-month-olds tested with different stimuli but had no effect on performance by 18-month-olds. One hallmark of memory development appears to be an age-related increase in the range of effective retrieval cues for a particular memory.     

The nature and basis of age-related changes in dynamic visual acuity

The ability of observers to resolve moving targets, or dynamic visual acuity (DVA), was determined for a group of young adults (M age = 19.6 years) and a group of older adults (M age = 67.6 years). Targets were presented at two luminance levels over a range of velocities (30, 60, 90, and 120 deg/s) and at 2 durations (200 and 600 ms). The younger subjects exhibited superior DVA under nearly all conditions, but this effect was essentially eliminated by the luminance adjustment. These results are interpreted in terms of decreased retinal illumination in the older subjects rather than in terms of age-related changes in the underlying eye movement systems. Practical and theoretical implications are discussed.     

The response-signal method reveals age-related changes in object working memory

Sixteen healthy young adults (ages 18-32) and 16 healthy older adults (ages 67-81) completed a delayed response task in which they saw the following visual sequence: memory stimuli (2 abstract shapes; 3,000 ms), a blank delay (5,000 ms), a probe stimulus of variable duration (one abstract shape; 125, 250, 500, 1,000, or 2,000 ms), and a mask (500 ms). Subjects decided whether the probe stimulus matched either of the memory stimuli; they were instructed to respond during the mask, placing greater emphasis on speed than accuracy. The authors used D. L. Hintzman & T. Curran's (1994) 3-parameter compound bounded exponential model of speed-accuracy tradeoff to describe changes in discriminability associated with total processing time. Group-level analysis revealed a higher rate parameter and a higher asymptote parameter for the young adult group, but no difference across groups in x-intercept. Proxy measures of cognitive reserve (Y. Stern et al., 2005) predicted the rate parameter value, particularly in older adults. Results suggest that in working memory, aging impairs both the maximum capacity for discriminability and the rate of information accumulation, but not the temporal threshold for discriminability.     

Differential trajectories of age-related changes in components of executive and memory processes

Several studies have demonstrated age-related declines in general executive function and memory. In this study, we examined cross-sectional and longitudinal age effects in more specific cognitive processes that constitute executive function and memory. We postulated that, whereas some components of executive and memory functions would show age differences and longitudinal declines, other specific abilities would be maintained or even improve with repeated testing. In a sample of individuals ≥55 years old from the Baltimore Longitudinal Study of Aging, we found longitudinal declines in inhibition, manipulation, semantic retrieval, phonological retrieval, switching, and long-term memory over a maximum of 14 years follow-up. In contrast, abstraction, capacity, chunking, discrimination, and short-term memory were maintained or even improved longitudinally, probably due in part to repeated testing. Moreover, whereas several different abilities were correlated across participants' cross-sectional performance, longitudinal changes in performance showed more heterogeneous trajectories. Finally, compared with cross-sectional performance, longitudinal trajectories showed better distinction between participants with and those without later cognitive impairment. These results show that longitudinal cognitive aging of executive and memory functions is not a uniform process but a heterogeneous one and suggest that certain executive and memory functions remain stable despite age-related declines in other component processes. (PsycINFO Database Record (c) 2012 APA, all rights reserved).     

Assessment of age-related changes in inhibition and binding using eye movement monitoring

Age-related memory deficits may result from attending to too much information (inhibition deficit) and/or storing too little information (binding deficit). The present study evaluated the inhibition and binding accounts by exploiting a situation in which deficits of inhibition should benefit relational memory binding. Older adults directed more viewing toward abrupt onsets in scenes compared with younger adults under instructions to ignore any such onsets, providing evidence for age-related inhibitory deficits, which were ameliorated with additional practice. Subsequently, objects that served as abrupt onsets underwent changes in their spatial relations. Despite successful inhibition of the onsets, eye movements of younger adults were attracted to manipulated objects. In contrast, the eye movements of older adults, who directed more viewing to the late onsets compared with younger adults, were not attracted toward manipulated regions. Similar differences between younger and older adults in viewing of manipulated regions were observed under free viewing conditions. These findings provide evidence for concurrent inhibition and binding deficits in older adults and demonstrate that age-related declines in inhibitory processing do not lead to enhanced relational memory for extraneous information.     

Sounds, words, sentences: age-related changes across levels of language processing

Age-related changes in sensory, lexical, and sentence processing were examined and compared using event-related potentials (ERPs) recorded as young and elderly participants listened to natural speech for comprehension. Lexically associated and unassociated word pairs were embedded in meaningful or syntactically legal but meaningless sentences. Early, general sensory, and attention-related responses (N1, P2) were delayed by about 25 ms for older participants, but later components indexing semantic processing (N400) were not delayed. There were no differences in the size, timing, or distribution of lexical associative effects for the two groups. In contrast, message-level context effects were delayed by more than 200 ms in the elderly group. The results support models that posit age-related changes primarily in higher order language processes.     

Cognitive abilities explaining age-related changes in time perception of short and long durations

The current study investigated how the development of cognitive abilities explains the age-related changes in temporal judgment over short and long duration ranges from 0.5 to 30 s. Children (5- and 9-year-olds) as well as adults were given a temporal bisection task with four different duration ranges: a duration range shorter than 1 s, two duration ranges longer than 3 s (4-8 s and >15 s), and an intermediate duration range (1.25-2.5 s). Their cognitive abilities were also assessed using a series of neuropsychological tests. The results showed that temporal sensitivity improved with age for each duration range but that this improvement occurred earlier for the short durations than for the long durations. Furthermore, the results revealed that the age-related improvement in time sensitivity for the durations shorter than 1 s was explained by the development of short-term memory span, whereas that for long durations was explained by the development of attention/executive functions. To summarize, the development of the abilities required to process long durations seems to be explained mainly by the development of attentional resources.     

Implicit and explicit adjustments to extrinsic visuo-motor transformations and their age-related changes

Humans have unique abilities in using tools. The skilled and goal-directed use of a tool implies that processes of motor control can be adjusted to the transformation of the movement of a part of the body into the movement of the effective part of the tool. A common example is the transformation of a hand movement in the motion of a cursor on a computer monitor. In part the adjustments to such transformations are implicit, that is, without conscious awareness of the novel transformation and the appropriate change of one’s own movements. However, the adjustments can also be explicit and intentional. We review a series of experiments which show that implicit and explicit adjustments to a novel visuo-motor gain are additive. This finding suggests that the processes which generate different types of adjustment are functionally independent. In a second series of experiments it turned out that at older adult age explicit adjustments to novel visuo-motor transformations are impaired, whereas implicit adjustments remain unaffected across working age.     

Achieving Coordination in Prehension: Joint Freezing and Postural Contributions

The focus of the present study was on the intersegmental relationships that emerge when both task and oganismic constraints are imposed upon the coordination system. Seven right-handed subjects were required to reach and grasp a cup (hand transport phase) and place it on a designated target (cup transport phase), using either their preferred or nonpreferred hand. The kinematics of the movement were examined as a function of task (grasping a full cup versus grasping an empty one) and organismic (preferred or nonpreferred hand) constraints. During the hand transport phase, a task constraint effect was revealed through an increase in the low-velocity phase for the full cup condition. This constraint coexisted with a decrease in angular motion of the shoulder and elbow joints, indicating subjects reduced the number of variables to be independently controlled in the final homing-in stage of the movement. Accompanying this decrease in angular change was an increase in the displacement of the trunk. During the cup transport phase, the trunk was shown to contribute significantly more to the movement in the full cup condition and for the left hand movements, thereby increasing the stability of the movement system. These findings are in agreement with Bernstein's (1967) notion of fixating parts of the body as an initial solution to a movement problem, and they lend support to the concept of a proximodistal organization of coordination.