Age-related differences in postural reaction time and coordination during voluntary sway movements

The elderly are known to exhibit declines in postural control during standing and walking, however little is known about how the elderly react under time-critical and challenging postural situations. The purpose of this study was to examine age-related differences in reaction time (RT) and the pattern of temporal coordination between center of pressure (COP), trunk and head motion during voluntary postural sway movements. Healthy young (n=10; mean=24 years; SD=5 years) and elderly men (n=8; mean=75 years; SD=2 years) stood on a force plate with tri-axial accelerometers attached to the head and lower trunk. Participants were required to generate sway in the anterior-posterior (AP) or medial-lateral (ML) direction in response to an auditory cue during two different testing conditions called Static reaction and Dynamic reaction. Static reactions involved the initiation of voluntary sway in either the AP or ML direction from quiet stance. Dynamic reactions involved an orthogonal switch of voluntary sway between the AP and ML directions. Compared to the young, elderly individuals exhibited slower RT during both Static and Dynamic reaction, and smaller differences in RT and phasing between COP, trunk, and head motion. The results of this study suggest that the elderly adopted more rigid coordination strategies compared to the young when executing a rapid change in direction of whole body motion. The rigid movement strategy of the elderly was presumably generated in an effort to compensate for increased challenge to the maintenance of stability.     

Age-related differences in the integration of sensory information during the execution of a bimanual coordination task

Young (n = 7) and elderly (n = 7) subjects performed bimanual coordination patterns in the transverse plane according to the in-phase or antiphase mode. Sensory information was manipulated through visual (with or without vision of the limbs) and proprioceptive input (with or without vibratory stimuli on one limb). Movement patterns with vibrations showed higher deviations from the intended relative phase than did those without vibrations. This finding suggests that the proprioceptive information induced by the vibrations and the movement interfered, leading to a disruption of the coordination patterns. In addition, as compared with the elderly, the young subjects performed more stable movements under normal circumstances but were more strongly affected by vibratory stimuli during the performance of in-phase movements. During antiphase movements, both age groups experienced a decrease of pattern stability. Furthermore, the absence or presence of visual feedback influenced the performance of the young subjects more than that of the elderly. The presence of vision led to stable in-phase movements, whereas a decrease of pattern stability was observed for antiphase movements. In general, these results demonstrate that manipulation of feedback sources affects young subjects more than elderly ones, and this can be related to a reduced sensory sensitivity as a function of aging.     

Age-related differences in collision detection during deceleration

Observers were presented with displays simulating a 3-D environment with obstacles in the path of motion. During the trial, observer motion decelerated at a constant rate and was followed by a blackout prior to the end of the display. On some trials the rate of deceleration resulted in stopping before the collision, whereas on other trials the rate of deceleration resulted in a collision with the obstacles. The observer's task was to detect which trials simulated an impending collision. Proportion of collision judgments was greater for older as compared with younger observers when a collision was not simulated. Older observers showed less sensitivity to detect collisions than younger observers did, particularly at high speeds. The age-dependent results are discussed in terms of analyses based on tau and constant deceleration. The results suggest that increased accident rates for older drivers may be due to an inability to detect collisions at high speeds.     

Age-related differences and the role of augmented visual feedback in learning a bimanual coordination pattern

The purpose of this study was to investigate the effects of aging and the role of augmented visual information in the acquisition of a new bimanual coordination pattern, namely a 90° relative phase pattern. In a pilot study, younger and older adults received augmented visual feedback in the form of a real-time orthogonal display of both limb movements after every fifth trial. Younger adults acquired this task over three days of practice and retained the task well over periods of one week and one month of no practice while the older adults showed no improvement at all on the task. It was hypothesized that the amount of augmented information was not sufficient for the older adults to overcome the strong tendency to perform natural, intrinsically stable coordination patterns, which consequently prevented them from learning the task. The present study evaluated the age-related role of augmented visual feedback for learning the new pattern. Participants were randomly assigned within age groups to receive either concurrent or terminal visual feedback after every trial in acquisition. In contrast to the pilot study, all of the older adults learned the pattern, although not to the same level as the younger adults. Both younger and older adults benefitted from concurrent visual feedback, but the older adults gained more from the concurrent feedback than the younger adults, relative to terminal feedback conditions. The results suggest that when learning bimanual coordination patterns, older adults are more sensitive to the structure of the practice conditions, particularly the availability of concurrent visual information. This greater sensitivity to the learning environment may reflect a diminished capacity for inhibitory control and a decreased ability to focus attention on the salient aspects of learning the task.     

Age-related differences in deception

Young and older participants judged the veracity of young and older speakers' opinions about topical issues. All participants found it easier to judge when an older adult was lying relative to a young adult, and older adults were worse than young adults at telling when speakers were telling the truth versus lying. Neither young nor older adults were advantaged when judging a speaker from the same age group. Overall, older adults were more transparent as liars and were worse at detecting lies, with older adults' worse emotion recognition fully mediating the relation between age group and lie detection failures.     

Interlimb coordination in prosthetic walking: effects of asymmetry and walking velocity

The present study focuses on interlimb coordination in walking with an above-knee prosthesis using concepts and tools of dynamical systems theory (DST). Prosthetic walkers are an interesting group to investigate from this theory because their locomotory system is inherently asymmetric, while, according to DST, coordinative stability may be expected to be reduced as a function of the asymmetry of the oscillating components. Furthermore, previous work on locomotion motivated from DST has shown that the stability of interlimb coordination increases with walking velocity, leading to the additional expectation that the anticipated destabilizing effect of the prosthesis-induced asymmetry may be diminished at higher walking velocities. To examine these expectations, an experiment was conducted aimed at comparing interlimb coordination during treadmill walking between seven participants with an above-knee prosthesis and seven controls across a range of walking velocities. The observed gait patterns were analyzed in terms of standard gait measures (i.e., absolute and relative swing, stance and step times) and interlimb coordination measures (i.e., relative phase and frequency locking). As expected, the asymmetry brought about by the prosthesis led to a decrease in the stability of the coordination between the legs as compared to the control group, while coordinative stability increased with increasing walking velocity in both groups in the absence of a significant interaction. In addition, the 2:1 frequency coordination between arm and leg movements that is generally observed in healthy walkers at low walking velocities was absent in the prosthetic walkers. Collectively, these results suggest that both stability and adaptability of coordination are reduced in prosthetic walkers but may be enhanced by training them to walk at higher velocities.     

Age-related differences in irrelevant-speech effects

Three experiments examined age-related differences in irrelevant-speech effects. Younger and older adults were required to recall short prose texts or lists of semantically related words presented visually together with distractor speech. In all experiments, older adults made more semantically related intrusion errors from the irrelevant speech than younger adults. Results of a source memory test suggested that these age-related differences in interference are most likely due to both inhibitory deficits and source-monitoring problems. The results lend partial support to the inhibition deficit theory of cognitive aging.     

Kinesthetic orientation judgments during later al head,body and trunk tilt

The effects of body, neck, and trunk tilt on judgments of kinesthetic verticality were compared using 104 Ss. The results showed that head tilt and body tilt produced equal and significant E effects and that trunk tilt produced no significant E effect. The data were interpreted as showing that otolith information is an important determinant of the kinesthetic E effect.     

Age-related differences and similarities in dual-task interference

Differences between younger adults (mean age, 20.7 years) and older adults (mean age, 72.7 years) in dual-task performance were examined in 7 experiments in which the overlap between 2 simple tasks was systematically varied. The results were better fit by a task-switching model in which age was assumed to produce generalized slowing than by a shared-capacity model in which age was assumed to reduce processing resources. The functional architecture of task processing appears the same in younger and older adults. There was no evidence for a specific impairment in the ability of older adults to manage simultaneous tasks. There was evidence for both input and output interference, which may be greater in older adults.     

Visual orientation during and after lateral head,body, and trunk tilt

Visual judgments of orientation were investigated during (effect) and after (aftereffect) different body postures. In Experiment 1 four trained Ss made apparent verticality (AV) judgments before and after 2 min in each of seven orientations: head tilt left and right, body tilt left and right, trunk tilt left and right and a control condition with head ’and body upright. The aftereffect was significant for all postures excepting trunk tilt left and the control. The aftereffect from head tilt was greater than that from the same degree of body tilt, and that in the trunk tilt condition was in the same direction as’ predicted from neck stimulation. In Experiment 2, 30 Ss made AV judgments during tilt in the same seven postures. The E-phenomenon resulted from both head and body tilts, and an effect was found for trunk tilt in the direction predicted from neck stimulation. The results are discussed in terms of the otolith, neck, and trunk receptor systems.     

Effects of velocity and limb loading on the coordination between limb movements during walking

The authors investigated the effects of velocity (increasing from 0.5 to 5.0 km/hr in steps of 0.5 km/hr) and limb loading on the coordination between arm and leg movements during treadmill walking in 7 participants. Both the consistency of the individual limb movements and the stability of their coordination increased with increasing velocity; the frequency coordination between arm and leg movements was 2:1 at the lower velocities and 1:1 at the higher velocities. The mass manipulation affected the individual limb movements but not their coordination, indicating that a stable walking pattern was preserved. The results differed qualitatively from those obtained in studies on bimanual interlimb coordination, implying that the dynamical principles identified therein are not readily applicable to locomotion.     

Age-related differences in inference revision processing

In comparison to younger adults, older adults demonstrate deficiencies in cognitive and linguistic abilities. Such cognitive factors that decline with age include working memory capacity and inhibitory abilities. The purpose of the present investigation was to measure differences in time course processing of inference revision abilities, as well as working memory, as they exist relative to adult age differences. Fifteen neurologically intact older adults and 15 younger adults participated in this study. A cross-modal lexical priming paradigm was chosen as the measure of the inference revision task; the listening span task of Tompkins, Bloise, Timko, and Baumgaertner (1994) was selected as the measure of working memory. Both groups demonstrated normal priming effects. No age-related differences were found on the working memory measure. Age-related differences did emerge on inferencing abilities. A significant correlation emerged between the older group's performance on comprehending inference revisions and their working memory capacity. Generally, inhibitory abilities and working memory capacity appeared to adversely affect older participant's performance.     

Age-related differences in localized attentional interference

Attentional selection of an object in the visual field degrades processing of neighboring stimuli in young adults. A pair of experiments examined the effects of aging on such localized attentional interference. In Experiment 1, younger and older observers made speeded same-different judgments of target shapes that varied in spatial separation. Performance declined for both age groups as the distance between targets decreased, but an Age x Distance interaction indicated that the magnitude of this effect was larger for older adults. Experiment 2 ruled out sensory masking as an explanation for these findings. Results indicate that older observers experience losses in the ability to attend to multiple spatially proximal stimuli within the visual field.     

Age-related differences in timing with breaks

Two groups of participants differing in age were compared on a time production task during which timing was temporarily interrupted. Produced intervals lengthened with increasing delay before the break occurrence, and the effect was more pronounced in older than in younger adults. A reaction time response to the signal beginning the break period was required also. Older participants responded more slowly to this signal, but they benefited to a greater extent from a lengthening of the time preceding its presentation. These results suggest that performance of older participants is affected by attention sharing and preparation involved in timing with breaks.     

Age-related changes and gender differences in time estimation

A study was carried out in which age and gender differences were studied in the performance of an empty interval production task. The duration of these intervals was 10 s, 1 and 5 min. The sample was made up of 140 subjects, half male and half female, in seven different age groups from 8 to 70 years old. The age range permitted us to identify when differences begin to be significant. The results show an age-related increase in the underproduction of the intervals. The differences between age groups attained significance from 51 to 60 years onward. With regard to gender, the main result was a greater underproduction of longer intervals (1 and 5 min) for women. These findings were interpreted in terms of different models of time estimation.     

Age-related differences in profiles of mood-change trajectories

As a group, older adults report positive affective lives. The extent to which there are subgroups of older adults whose moods are less positive, however, is unclear. Our aim in the present study was to identify and characterize different subgroups of adults who exhibit distinct trajectories of mood change across a relatively short time period. Seventy-nine young and 103 older adults continuously reported their moods while viewing emotional and neutral faces. Cluster analysis revealed four subgroups of mood-change trajectories. Both the most positive and the most negative subgroups included more older than young adults (ps < .05), suggesting that not all older adults exhibit higher positive affect than young adults. Analyses of variance revealed that the most negative group exhibited slower processing speed, more state anxiety and neuroticism, and looked less at happy faces than the other groups (ps < .05). The results are discussed from an adult developmental perspective, focusing on the increased variability of mood trajectories in the older adults and whether this is a reflection of adaptive functioning or a potential harbinger of dysfunction.     

Age-related differences in the attentional white bear

Psychonomic Bulletin & Review - The cognitive aging literature suggests that aging populations exhibit impairments in the proactive inhibition of attention. Although proactive inhibition is...