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Search Results: 1 - 10 of 928 matches for " Otmar Bock "
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Transfer of Visuomotor Adaptation to Unpractised Hands and Sensory Modalities  [PDF]
Otmar Bock, Gerd Schmitz
Psychology (PSYCH) , 2013, DOI: 10.4236/psych.2013.412145
Abstract:

A recent model (Bock, 2013) predicts that sensorimotor adaptation, achieved while pointing at visual targets, will transfer fully to acoustic targets. The model further predicts that visual-to-acoustic transfer is not diminished even if the left and right arms have adapted to a different distortion. To scrutinize these predictions, we asked subjects to point at visual targets with their right hands under a +30 deg rotation of visual feedback (group “single”), or alternately, with their right hands under a +30 deg and with their left hands under a -30 deg rotation of visual feedback. Aftereffects were registered for each hand and for visual as well as acoustic targets, in counterbalanced order. We found that acoustic aftereffects were only about 66% of visual ones, which violates the first prediction and calls for an amendment of the model. We further found that acoustic aftereffects were of similar magnitude in both groups, which supports the second prediction. Finally, we observed an intermanual transfer of only about 29%. These findings suggest that unpractised acoustic inputs are weighted somewhat lower than practised visual ones, and that outputs to the unpractised left hand are weighted substantially lower than those to the practised right hand.

Dependence of Manual Grasping on the Behavioral Context: A Comparison between Arms and between Age Groups  [PDF]
Otmar Bock, Benjamin Baak
Psychology (PSYCH) , 2013, DOI: 10.4236/psych.2013.412144
Abstract:

We evaluated the kinematics and dynamics of grasping in a typical laboratory situation (L) and in a more everyday-like situation (E), using right-handed subjects. Performance was compared when young subjects used their right versus left arm, and when young versus old subjects used their left arm. As in our previous work, multiple differences emerged between parameter values in the two contexts, L and E. These context differences were, however, more pronounced for the left rather than for the right arm of young subjects, and more pronounced for the left arm of young rather than older subjects. We propose an explanation based on the differential involvement of the dorsal and ventral cortical processing stream in L and in E: The differential involvement would be accentuated for the left arm of young, but not for the left arm of older subjects.

Dual-task costs while walking increase in old age for some, but not for other tasks: an experimental study of healthy young and elderly persons
Otmar Bock
Journal of NeuroEngineering and Rehabilitation , 2008, DOI: 10.1186/1743-0003-5-27
Abstract: Healthy young and elderly subjects were tested under five different combinations of a walking and a non-walking task. The results were analysed jointly with those of a previous study from our lab, such that a total of 13 task combinations were evaluated. For each task combination and subject, we calculated the mean dual-task costs across both constituent tasks, and quantified ARD as the difference between those costs in elderly and in young subjects.An analysis of covariance yielded no significant effects of obstacle presence and overall task difficulty on ARD, but a highly significant effect of visual demand: non-walking tasks which required ongoing visual observation led to ARD of more than 8%, while those without such requirements led to near-zero ARD. We therefore concluded that the visual demand of the non-walking task is critical for the emergence of ARD while walking.Combinations of walking and concurrent visual observation, which are common in everyday life, may contribute towards disturbed gait and falls during daily activities in old age. Prevention and rehabilitation programs for seniors should therefore include training of such combinations.Human gait deteriorates in old age. Walking speed and the stability of the walking pattern decrease [1-3], and the incidence of falls increases dramatically: about 25% of the 70 year olds, 35% of the 75 year olds, and 50% of the over 80 year olds fall at least once per year [4-6]. Many of these falls don't result in physical injury, but they often have negative psychosocial consequences such as fear of falling, self-imposed inactivity, dependence on others [7], and ultimately, admittance into nursing homes [8]. To counteract this downward spiral, it is important to understand the reasons why locomotion is degraded in the elderly and, based on this understanding, to develop efficient prevention and rehabilitation programs.Previous studies proposed various explanations for gait impairments in old age, such as reduced se
Semantic Priming of Attention Focus: Evidence for Short- and Long-Term Effects  [PDF]
Stefanie Hüttermann, Daniel Memmert, Otmar Bock
Psychology (PSYCH) , 2012, DOI: 10.4236/psych.2012.32019
Abstract: Research on subliminal priming documents that our brain can understand words, interpret facial expressions and decode symbols even without realizing them consciously. Thus, words presented for merely a few ms can shorten the response times to semantically related target words, if compared to words with opposite meaning (e.g., Klauer & Musch, 2003). While most previous semantic priming studies used semantic prime-target pairs of affective valence, the present study explored for the first time semantic priming effects for prime-target pairs characterizing an attentional focus. In Experiment 1, a subliminally presented prime word was followed by an above-threshold target word such that both words denoted a broad attention focus, both denoted a narrow focus, or one word denoted a broad and the other a narrow focus. Subjects had to judge the focus of the target words, and we found their response times to be shorter when the prime-target pairs were semantically congruent rather than incongruent. In Experiment 2, a block of subliminally presented prime words, all denoting a broad or all a narrow focus of attention, was followed by a block of subliminally presented target words denoting a broad or a narrow focus in a mixed sequence. Subjects had to judge the position of each prime or target, and we found their target response times to be shorter when the target was semantically congruent rather than incongruent with the preceding prime block. We concluded that semantic priming is effective, that it works for primes denoting the attention focus, and that it persists for more than just a fraction of a second.
Subliminal Priming of Motivation Magnitude  [PDF]
Fabian Steinberg, Otmar Bock, Sebastian Dern
Psychology (PSYCH) , 2013, DOI: 10.4236/psych.2013.411115
Abstract:

Word primes have been successfully used in the past to facilitate the processing of other words (semantic priming), but also to modify mental states such as emotion, cognition and motivation (conceptual priming). This work documented that the direction of motivational drive can be successfully changed, but left open whether its magnitude can be influenced as well. To find out, we asked subjects to point at subliminally presented (30 ms) words that denoted low motivation (13 subjects) or high motivation (13 subjects). Afterwards, subjects completed a questionnaire of learning-specific motivation. No effect of priming was found for pointing parameters such as reaction time, but an effect emerged for self-assessed motivation level. The subject group primed with high-motivation words rated their motivation higher than the group primed with low-motivation words. The results indicate that not only the direction, but also the level of motivation can be manipulated subliminally, and supports the view that motivation can influence behavior without actor’s explicit knowledge.

Double-Step Adaptation of Saccadic Eye Movements Is Influenced by Priming with Age Stereotypies  [PDF]
Otmar Bock, Valentina Grigorova, Milena Ilieva
Psychology (PSYCH) , 2013, DOI: 10.4236/psych.2013.412147
Abstract:

Age related deficits of sensorimotor adaptation have been observed earlier with arm, but not with eye movements. Here we evaluate whether deficits of eye adaptation may depend on the subjects’ believes about their own sensorimotor abilities. To find out, elderly subjects were primed with positive or negative age stereotypes using the scrambled-sentence task, and were then exposed to a double-step saccade adaptation task. The outcome was compared to data from an earlier study with unprimed elderly persons. We found adaptation to be stronger after positive priming than after negative or no priming, with no difference between the latter two. Aftereffects of adaptation were not modified by priming. From this we conclude that positive primes enhanced workaround strategies, but not adaptive recalibration, while negative primes failed completely, possibly because of a floor effect.

Unconscious Priming of Focused Attention Reduces the Attention Deficits of ADHD Patients  [PDF]
Elaheh Hosseini, Otmar Bock, Monika Thomas
Psychology (PSYCH) , 2016, DOI: 10.4236/psych.2016.76084
Abstract:

We have shown before that attention deficit hyperactivity disorder (ADHD) children suffer from deficits of sustained attention, while divided, selective and distributed attention is largely spared. The present study explores whether these deficits can be ameliorated by unconscious priming of attention. Sixty children diagnosed with ADHD participated, their age ranged between eight and twelve years. Participants were primed with the scrambled sentence task: under the pretext of a language comprehension task, they were exposed to words referring to focused attention (group “focused”) or scattered attention (group “scattered”), or were not exposed to attention-related words (group “control”). All three groups were then assessed with the same battery of attention tests used in our earlier study. We found that compared to the “control” group, performance was higher in the “focused” group on tests of sustained, divided and distributed attention, and was lower in the “scattered” group on all four tests. From this we conclude that unconscious priming can modify the attention of ADHD children, and that this modification extends to the one attention component that is most affected by ADHD. Unconscious priming might therefore be an expedient supplementary method for ADHD treatment, as it can be administered at virtually no cost anytime, anywhere.

Effects of a Visual Distracter Task on the Gait of Elderly versus Young Persons
Otmar Bock,Rainer Beurskens
Current Gerontology and Geriatrics Research , 2011, DOI: 10.1155/2011/651718
Abstract: Seniors show deficits of dual-task walking when the second task has high visual-processing requirements. Here, we evaluate whether similar deficits emerge when the second task is discrete rather than continuous, as is often the case in everyday life. Subjects walked in a hallway, while foot proprioception was either perturbed by vibration or unperturbed. At unpredictable intervals, they were prompted to turn their head and perform a mental-rotation task. We found that locomotion of young subjects was not affected by this distracter task with or without vibration. In contrast, seniors moved their legs after the distraction at a slower pace through smaller angles and with a higher spatiotemporal variability; the magnitude of these changes was vibration independent. We conclude that the visual distracter task degraded the gait of elderly subjects but completely spared young ones, that this effect is not due to degraded proprioception, and that it rather might reflect the known decline of executive functions in the elderly. 1. Introduction The human gait pattern is affected by old age. For example, walking speed and stride length decrease, while lateral sway, foot velocity at ground contact, and stride time variability increase [1–5]. Some of these changes are compensatory in that they stabilize body posture, while others are dysfunctional and correlate with the risk of accidental falls [6, 7]. The observed deficits have been attributed in literature to a variety of causal factors, notably to cognitive decline; indeed, the critical role of cognition is supported by the fact that age-related gait changes are more pronounced in persons with cognitive impairment [8, 9] and that they are accentuated under dual-task conditions [10, 11]. We have recently compared single- and dual-task gait of young and elderly subjects with 14 different combinations of a walking and a nonwalking task and found age-related deficits of dual-task gait for some but not for other combinations. Specifically, we observed deficits whenever the non-walking tasks required continuous visual processing and no deficits without such a requirement, irrespective of the difficulty of the walking and the nonwalking task [12–15]. We attributed this finding to the well-known shrinkage of prefrontal gray matter in advanced age and the associated decline of executive functions [16, 17]. According to this view, walking relies on continuous visual processing to control heading and avoid obstacles as we navigate through a visually defined environment [18–20]; when a visual nonwalking task is added, two
Age-Related Deficits of Dual-Task Walking: A Review
Rainer Beurskens,Otmar Bock
Neural Plasticity , 2012, DOI: 10.1155/2012/131608
Abstract: This review summarizes our present knowledge about elderly people's problems with walking. We highlight the plastic changes in the brain that allow a partial compensation of these age-related deficits and discuss the associated costs and limitations. Experimental evidence for the crucial role of executive functions and working memory is presented, leading us to the hypothesis that it is difficult for seniors to coordinate two streams of visual information, one related to navigation through visually defined space, and the other to a visually demanding second task. This hypothesis predicts that interventions aimed at the efficiency of visuovisual coordination in the elderly will ameliorate their deficits in dual-task walking. 1. Introduction Accidental falls in old age are an increasing problem in our graying society, and they have received a lot of attention in recent research. About 30% of persons aged 65+ years and about 50% of those aged 85+ years fall at least once a year and the probability of falling again increases after each fall [1–3]. Early research addressed environmental hazards, sensorimotor deficits, and impaired balance as risk factors for accidental falls [4, 5], but more recent work focuses on the role of cognition [6, 7]. According to this recent approach, age-related deficits of locomotion can be partly compensated by cognitive workaround strategies, thus replacing automated sensorimotor processing with effortful higher-order functions. This is a good example of neural plasticity, as it shows that deficits arising in one part of the nervous system can be overcome by engaging another part of that system. Persons with a reduced cognitive capacity have only limited access to this compensation: according to empirical research, they are more likely to walk unsteadily and their risk of falling is higher [8]. Brain plasticity may help overcome the gait problems in old age, but there is a price to pay: cognitive resources allocated to seniors’ locomotion are no longer available for other activities while walking, such as obstacle avoidance, navigation along a planned route, watching for pedestrian and vehicular traffic, as well as engaging in gait-unrelated tasks. As a consequence, elderly persons often have larger problems than younger ones to walk and concurrently engage in another activity [6, 7]. 2. Anatomical Changes in the Human Brain as a Function of Age Early studies in the 1990s were already able to show age-related changes in the human brain [9–11]. Older people are affected by a general loss of brain mass and a distinctive atrophy
Age-related deficits of manual grasping in a laboratory versus in an everyday-like setting
Otmar Bock,Fabian Steinberg
Ageing Research , 2012, DOI: 10.4081/ar.2012.e7
Abstract: This study compared the grasping performance of 24 younger (20-30 years of age) and 24 older subjects (60-70 years of age) in a typical laboratory task (L) where movements were repetitive, externally triggered, purposeless and attention-attracting, and in an everydaylike task (E) where movements were part of a rich behavioral repertoire, internally initiated, purposive and little attended. We registered a wide range of kinematic and force parameters, and calculated their within-subject means and variation coefficients. Multiple differences emerged between the parameter values in L and E. Factor analysis reduced them to five independent effects. We also found multiple differences between the two age groups, with seniors responding more slowly and in a more stereotyped fashion. Multiple significant task x age interactions emerged as well, with age differences being more pronounced in E than in L. The latter finding is of practical relevance, since it suggests that age-related deficits in some real-life situations may be underestimated in laboratory research. It also is of theoretical relevance: it indicates that brain regions which are particularly vulnerable to aging may contribute to task E more than to task L.
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