Exploring how arm movement moderates the effect of task difficulty on balance performance in young and older adults

Emerging evidence highlights that arm movements exert a substantial and functionally relevant contribution on quiet standing balance control in young adults. Ageing is associated with “non-functional” compensatory postural control strategies (i.e., lower limb co-contraction), which in turn, may increase the reliance on an upper body strategy to control upright stance. Thus, the primary purpose of this study was to compare the effects of free versus restricted arm movements on balance performance in young and older adults, during tasks of different difficulty. Fifteen young (mean ± SD age; 21.3 ± 4.2 years) and fifteen older (mean ± SD age; 73.3 ± 5.0 years) adults performed bipedal, semi-tandem and tandem balance tasks under two arm position conditions: restricted arm movements and free arm movements. Centre of pressure (COP) amplitude and frequency were calculated as indices of postural performance and strategy, respectively. Especially in older adults, restriction of arm movement resulted in increased sway amplitude and frequency, which was primarily observed for the mediolateral direction. Further, increasing balance task difficulty raised the arm restriction cost (ARC; a new measure to quantify free vs. restricted arm movement differences in postural control) that was more prominent in older adults. These findings indicate the ARC provides a measure of reliance on the upper body for balance control and that arm movement is important for postural control in older adults, especially during tasks of greater difficulty.     

Aging and the revelation effect

Previous research by M. W. Prull, L. L. Light, M. E. Collett, and R. F. Kennison (1998) has shown that older adults are not susceptible to a memory illusion referred to as the revelation effect. The authors examined the robustness of Prull et al.'s findings by having participants solve a word fragment (Experiment 1) or an anagram (Experiment 2) prior to the recognition memory decision. In both experiments, younger and older adults showed a reliable revelation effect. These results simultaneously challenge both the conclusion that older adults are not vulnerable to the revelation effect and the conclusion that aging is associated with increasing susceptibility to memory illusions.     

Processing strategy moderates the cultivation effect

This study tested the hypothesis that processing strategy moderates the effect of television viewing on social perceptions (cultivation effect). One hundred twenty‐two male and female students provided estimates of the prevalence of crime, occupations, affluence, and marital discord under one of three conditions. Some participants were induced to process heuristically (heuristic group) through instructions to provide their estimates spontaneously with little elaboration. Other participants were induced to process systematically (systematic group) through an accuracy motivation/task importance manipulation. A third (control) group received instructions to simply answer the questions. The results indicated that processing strategy moderated the cultivation effect such that cultivation effects were noted in the heuristic and control groups but not in the systematic group. These results are consistent with the notion that the cultivation effect can be explained in part as the result of heuristic processing through lack of source discounting, and they provide support for the heuristic processing model of cultivation effects.     

Task difficulty, cardiovascular response, and the magnitude of goal valence

Sixty-four young women expected to perform an easy, moderately difficult, or extremely difficult memory task with the opportunity to earn a small incentive for good performance. Cardiovascular (heart rate, systolic and diastolic blood pressure) and subjective measures were taken immediately prior to task performance. Both systolic blood pressure (SBP) responses and ratings of goal attractiveness were nonmonotonically related to expected task difficulty, with the most pronounced SBP elevations and highest goal attractiveness in the moderately difficult task condition. Product-moment correlations among cardiovascular response measures revealed a strong positive association between systolic and diastolic pressure (but not heart rate) change in the easy condition, positive relationships among all measures in the moderately difficult condition, and no significant correlations in the extremely difficult condition. Subjective measures of arousal were not affected by the task difficulty manipulation. Principal findings are discussed in terms of a theoretical model proposed by Brehm (1979) that states that motivation varies as a nonmonotonic function of the difficulty of goal attainment. Intercorrelations among cardiovascular response variables are considered in terms of their possible indication of the mechanisms underlying blood pressure changes associated with variations in motivation.     

Recollection-based recognition eliminates the revelation effect in memory

The revelation effect refers to the tendency to call an item on a recognition test old if it is preceded by a cognitive task that involves the processing of a similar stimulus (Watkins &; Peynircioglu, 1990). It has been proposed that the revelation effect occurs because of an increase in the familiarity of the test items in the revelation condition (Luo, 1993; Westerman &; Greene, 1998). In the present experiments, the revelation effect was investigated in recognition tasks that were not based solely on the familiarity of the test items but,also, on a recall-like retrieval process. A revelation effect was not found on an associative-recognition task or on a plurality recognition task. The results of this study show that the revelation effect does not occur when the contribution of familiarity to recognition decisions is reduced by factors that encourage the recollection of the study episode.     

Conditions affecting the revelation effect for autobiographical memory

In four experiments involving 184 participants, people rated their confidence that particular events had happened in their childhood (e.g., "Broke a window playing ball"). If participants had to unscramble a key word in a phrase just before rating it (e.g., "Broke a nwidwo [window] playing ball"), confidence ratings increased-the revelation effect. However, the pattern of revelation effects depended on the particular way in which participants processed key words (e.g., visualizing vs. counting vowels in the word window) approximately 10 min prior to rating life events that contained those words. Prior exposure to key words never in itself directly affected confidence ratings. These results demonstrate that one can manipulate the revelation effect by altering the processing that participants perform on words prior to unscrambling them. These results also pose difficulties for many accounts of the revelation effect. The major puzzle posed by our present findings is that unscrambling key words increases confidence that an event has happened in childhood, whereas prior exposure to these words does not.     

The revelation effect in frequency judgment

In three experiments, we explored the revelation effect in a frequency judgment task. Participants estimated the frequency of words that had been presented one, two, four, or eight times. At test, half the words were revealed by completing word fragments, and half were presented intact. Estimated frequencies were reliably higher for revealed than for intact words, and in two of the three experiments, the revelation effect became larger as actual frequency increased. A revelation effect was obtained whether the revealed word was the same as (Experiment 1) or different from (Experiment 2) the word judged for frequency. Frequency estimates were higher for more distorted test items (Experiment 3).     

An event-related potential study of the revelation effect

Event-related potentials (ERPs) were recorded during a verbal recognition memory task in order to investigate whether changes in familiarity are part of the explanation for the revelation effect. For half of the test words, participants solved an anagram prior to making the old/new recognition judgment. A revelation effect was obtained: When test words were preceded by the anagram task, a higher probability of an old response was associated with the items than was otherwise the case. The ERPs recorded time-locked to the onset of the test words were separated according to old/new status andthe presence/absence of the anagram task. The ERP index of familiarity was of lower amplitude for both old and new items that were preceded by the anagram task. These findings are consistent with the view that part of the explanation for the revelation effect is a reduction in the familiarity of the critical test items.     

Ego involvement moderates the assimilation effect of affective expectations

Based on the affective expectations model and research on mental effort mobilization, two experiments manipulated affective expectations (no expectations versus positive expectations) and ego involvement (low versus high) and assessed participants’ affective reactions to hedonically neutral stimuli. In Experiment 1, evaluations were more positive when participants had positive expectations about neutral photos—but only when ego involvement was low. High ego involvement neutralized this affective expectation assimilation effect. Experiment 2 replicated these findings for experienced mood after reading a hedonically neutral short essay. Furthermore, high ego involvement led to longer response latencies in the affect ratings in Study 1. The findings support the idea that high ego involvement resulted in relatively high mental effort that was necessary to detect discrepancies between affective expectations and stimuli’s real affective potential and therefore moderated the assimilation effect to affective expectations.

Mix me a list: Context moderates the truth effect and the mere-exposure effect

When participants are repeatedly presented with an unfamiliar stimulus, this stimulus is rated as more likable (mere-exposure effect) or more valid (truth effect) as compared with a similar non-repeated stimulus. Both effects have been discussed as effects of fluency. Typical research designs on these effects involve a test phase in which ratings of both repeated and non-repeated stimuli are required. Based on research on moderators of fluency effects, we propose that the procedure of assessing the effects with mixed lists of repeated and non-repeated stimuli contributes strongly to the emergence of both effects. Two experiments found that the truth effect and the mere-exposure effect were strongly moderated by whether mixed lists or only repeated items were used at the test phase: whereas strong effects occurred in a context of repeated and non-repeated stimuli, the effects vanished with only repeated stimuli. Methodological and theoretical implications are discussed.     

任务难度对自闭症儿童视觉搜索优势显现的影响

探究自闭症谱系障碍(ASD)儿童视觉搜索优势的显现是否受任务难度影响及优势存在机理。本研究采集ASD和正常发育(TD)儿童完成不同难度等级视觉搜索任务的行为和眼动数据。结果发现：在高难度等级任务中ASD组的准确率显著高于TD组;ASD组在任务中对目标刺激的回视次数、对靶子和外周感兴趣区的注视时间显著少于TD组,且ASD组偏好注视刺激的右侧区域。结果表明ASD儿童视觉搜索优势显现受任务难度影响,且可能与其对干扰刺激增强的知觉能力有关。     

Task difficulty and visual similarity increase a distractor's effects on random shapes

Recognition of random shapes followed by a visual distractor is altered by the type of distractor and whether the distractor needs to be attended. Three experiments tested which characteristics modify a visual distractor's effect on random target shapes presented for 75 to 150 msec. Exp. 1 showed that increasing the number of digits to be remembered (1, 3, or 8) increased the effectiveness of digits as distractors. Exeir effect as visual distractors for random target shapes. Random shapes were highly effective as distractors, while pictures of faces or comples colored pictures had a relatively small effect. In Exp. 3 decreasing the presentation time for novel visual distractors decreased recognition of the distractors but not of random target shapes. However, adding a three-digit distractor after the novel visual distractor did decrease recognition of target shapes. Exps. 2 and 3 showed that the order of the recognition tests of the target and distracting stimuli altered target recognition if and only if subjects did know which was to be reported first. These experiments indicate that the effect of a visual distractor depends on both the extent to which it is allotted attention and its visual similarity to the target stimulus.     

Task difficulty and response complexity modulate affective priming by emotional facial expressions

In this study we used an affective priming task to address the issue of whether the processing of emotional facial expressions occurs automatically independent of attention or attentional resources. Participants had to attend to the emotion expression of the prime face, or to a nonemotional feature of the prime face, the glasses. When participants attended to glasses (emotion unattended), they had to report whether the face wore glasses or not (the glasses easy condition) or whether the glasses were rounded or squared (the shape difficult condition). Affective priming, measured on valence decisions on target words, was mainly defined as interference from incongruent rather than facilitation from congruent trials. Significant priming effects were observed just in the emotion and glasses tasks but not in the shape task. When the key–response mapping increased in complexity, taxing working memory load, affective priming effects were reduced equally for the three types of tasks. Thus, attentional load and working memory load affected additively to the observed reduction in affective priming. These results cast some doubts on the automaticity of processing emotional facial expressions.     

Task performance and electromyopotential as functions of task difficulty and EMG feedback

The dearth of empirical research in the application of biofeedback is discussed. Exp. 1 assessed relationships among biofeedback EMG training, EMG levels, cognitive task performance, and task difficulty. 72 subjects (male or female college students) were administered 1 trial on an iconic memory task with either EMG audio feedback, sham EMG audio feedback, or no feedback. Three levels of task difficulty were used. One 20-min. training session significantly lowered EMG responses, and task performance was inversely related to task difficulty. No relationship between EMG level and task performance was observed. Exp. 2 investigated the effect of increased EMG responses on cognitive task performance for one level of difficulty. One biofeedback training session did not significantly increase frontalis EMG, and there was no relationship between increased EMG and task performance.     

Self-motivation moderates effect of exercise-induced feelings on adherence

The effect of cardiovascular exercise-induced feeling state changes on exercise program attendance was assessed with mixed-sex, adult new exercisers (N = 72) using the Exercise-induced Feeling Inventory. Positive/Nonpositive patterns of after-exercise affective change were not significantly associated with attendance. When participants' scores on the Self-motivation Inventory of 1980 were analyzed, a significant portion of the variance in attendance (R2 = .10, F = 3.94, p<.03) was explained. A similar, but not significant R2 of .077 was noted when the single Exercise-induced Feeling Inventory subscale of Physical Exhaustion was assessed using the same multiple regression method. Implications for adherence of new exercisers and its dependence on self-motivation and exercise-induced changes in feeling states were discussed. The need to replicate findings across various types of participant, exercise, and setting was emphasized.     

Event-related potential evidence for multiple causes of the revelation effect

Asking people to discover the identity of a recognition test probe immediately before making a recognition judgment increases the probability of an old judgment. To inform theories of this "revelation effect," event-related potentials (ERPs) were recorded for revealed and intact test items across two experiments. In Experiment 1, we used a revelation effect paradigm where half of the test probes were presented as anagrams (i.e., a related task) and the other items were presented intact. The pattern of ERP results from this experiment suggested that revealing an item decreases initial familiarity levels and caused the revealed items to elicit similar levels of activity. In Experiment 2, half of the probes were preceded by an addition task (i.e., an unrelated task). The pattern of ERP effects in this study were distinct from those observed in Experiment 1. More specifically, revealed item ERPs were more negative than intact ERPs at frontal electrodes and more positive at parietal electrodes early in the interval. Later in the epoch, revealed item ERPs were more negative than intact items. These data suggest that related tasks decrease familiarity and alter the signal-to-noise ratio of old and new items, whereas unrelated tasks affect processing in a different way (perhaps by changing decision processes) that also results in the revelation effect. The implications for current theories of the revelation effect are discussed.     

The effect of the feeling of resolution and recognition performance on the revelation effect

The fact that engaging in a cognitive task before a recognition task increases the probability of “old” responses is known as the revelation effect. We used several cognitive tasks to examine whether the feeling of resolution, a key construct of the occurrence mechanism of the revelation effect, is related to the occurrence of the revelation effect. The results show that the revelation effect was not caused by a visual search task, which elicited the feeling of resolution, but caused by an unsolvable anagram task and an articulatory suppression task, which did not elicit the feeling of resolution. These results suggest that the revelation effect is not related to the feeling of resolution. Moreover, the revelation effect was likely to occur in participants who performed poorly on the recognition task. The result suggests that the revelation effect is inclined to occur when people depend more on familiarity than on recollection process.