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| Author | Friedman, Jason; Brown, Scott; Finkbeiner, Matthew | ||||
| Title | Linking cognitive and reaching trajectories via intermittent movement control | Type | Journal Article | ||
| Year | 2013 | Publication | Journal of Mathematical Psychology | Abbreviated Journal | |
| Volume | 57 | Issue | 3-4 | Pages | 140-151 |
| Keywords | Decision making; Diffusion model; Reaction times; Arm movements; Submovements | ||||
| Abstract | Theories of decision-making have traditionally been constrained by reaction time data. A limitation of reaction time data, particularly for studying the temporal dynamics of cognitive processing, is that they index only the endpoint of the decision making process. Recently, physical reaching trajectories have been used as proxies for underlying mental trajectories through decision space. We suggest that this approach has been oversimplified: while it is possible for the motor control system to access the current state of the evidence accumulation process, this access is intermittent. Instead, we demonstrate how a model of arm movements that assumes intermittent, not continuous, access to the decision process is sufficient to describe the effects of stimulus quality and viewing time in curved reaching movements. | ||||
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Approved | no | |||
| Call Number | Serial | 70 | |||
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| Author | Park, J.; Pazin, N.; Friedman, J.; Zatsiorsky, V.M.; Latash, M.L. | ||||
| Title | Mechanical properties of the human hand digits: Age-related differences | Type | Journal Article | ||
| Year | 2014 | Publication | Clinical Biomechanics | Abbreviated Journal | |
| Volume | 29 | Issue | 2 | Pages | 129–137 |
| Keywords | hand; aging; friction; apparent stiffness; damping | ||||
| Abstract | Background Mechanical properties of human digits may have significant implications for the hand function. We quantified several mechanical characteristics of individual digits in young and older adults. Methods Digit tip friction was measured at several normal force values using a method of induced relative motion between the digit tip and the object surface. A modified quick-release paradigm was used to estimate digit apparent stiffness, damping, and inertial parameters. The subjects grasped a vertical handle instrumented with force/moment sensors using a prismatic grasp with four digits; the handle was fixed to the table. Unexpectedly, one of the sensors yielded leading to a quick displacement of the corresponding digit. A second-order, linear model was used to fit the force/displacement data. Findings Friction of the digit pads was significantly lower in older adults. The apparent stiffness coefficient values were higher while the damping coefficients were lower in older adults leading to lower damping ratio. The damping ratio was above unity for most data in young adults and below unity for older adults. Quick release of a digit led to force changes in other digits of the hand, likely due to inertial hand properties. These phenomena of “mechanical enslaving” were smaller in older adults although no significant difference was found in the inertial parameter in the two groups. Interpretations The decreased friction and damping ratio present challenges for the control of everyday prehensile tasks. They may lead to excessive digit forces and low stability of the grasped object. |
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| ISSN | 0268-0033 | ISBN | Medium | ||
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| Notes |
Approved | no | |||
| Call Number | Serial | 73 | |||
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| Author | Portnoy, S.; Rosenberg, L.; Alazraki, T.; Elyakim, E.; Friedman, J. | ||||
| Title | Differences in Muscle Activity Patterns and Graphical Product Quality in Children Copying and Tracing Activities on Horizontal or Vertical Surfaces | Type | Journal Article | ||
| Year | 2015 | Publication | Journal of Electromyography and Kinesiology | Abbreviated Journal | Journal of Electromyography and Kinesiology |
| Volume | 25 | Issue | 3 | Pages | 540�547 |
| Keywords | Motor equivalence; Electromyography; Tablet; Occupational Therapy; Muscle fatigue; Motor control | ||||
| Abstract | The observation that a given task, e.g. producing a signature, looks similar when created by different motor commands and different muscles groups is known as motor equivalence. Relatively little data exists regarding the characteristics of motor equivalence in children. In this study, we compared the level of performance when performing a tracing task and copying figures in two common postures: while sitting at a desk and while standing in front of a wall, among preschool children. In addition, we compared muscle activity patterns in both postures. Specifically, we compared the movements of 35 five- to six-year old children, recording the same movements of copying figures and path tracing on an electronic tablet in both a horizontal orientation, while sitting, and a vertical orientation, while standing. Different muscle activation patterns were observed between the postures, however no significant difference in the performance level was found, providing evidence of motor equivalence at this young age. The study presents a straightforward method of assessing motor equivalence that can be extended to other stages of development as well as motor disorders. | ||||
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| ISSN | 1050-6411 | ISBN | Medium | ||
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| Notes |
Approved | no | |||
| Call Number | Serial | 77 | |||
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| Author | Zopf, R.; Friedman, J.; Williams, M.A. | ||||
| Title | The plausibility of visual information for hand ownership modulates multisensory synchrony perception | Type | Journal Article | ||
| Year | 2015 | Publication | Abbreviated Journal | Experimental Brain Research | |
| Volume | 233 | Issue | 8 | Pages | 2311-2321 |
| Keywords | Multisensory perception; Temporal synchrony perception; Virtual hand; Body representations; Body ownership; Sensory predictions | ||||
| Abstract | We are frequently changing the position of our bodies and body parts within complex environments. How does the brain keep track of one’s own body? Current models of body ownership state that visual body ownership cues such as viewed object form and orientation are combined with multisensory information to correctly identify one’s own body, estimate its current location and evoke an experience of body ownership. Within this framework, it may be possible that the brain relies on a separate perceptual analysis of body ownership cues (e.g. form, orientation, multisensory synchrony). Alternatively, these cues may interact in earlier stages of perceptual processing—visually derived body form and orientation cues may, for example, directly modulate temporal synchrony perception. The aim of the present study was to distinguish between these two alternatives. We employed a virtual hand set-up and psychophysical methods. In a two-interval force-choice task, participants were asked to detect temporal delays between executed index finger movements and observed movements. We found that body-specifying cues interact in perceptual processing. Specifically, we show that plausible visual information (both form and orientation) for one’s own body led to significantly better detection performance for small multisensory asynchronies compared to implausible visual information. We suggest that this perceptual modulation when visual information plausible for one’s own body is present is a consequence of body-specific sensory predictions. | ||||
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| Publisher | Springer Berlin Heidelberg | Place of Publication | Editor | ||
| Language | English | Summary Language | Original Title | ||
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| ISSN | 0014-4819 | ISBN | Medium | ||
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| Notes |
Approved | no | |||
| Call Number | Serial | 78 | |||
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| Author | Awasthi, B.; Williams, M.A.; Friedman, J. | ||||
| Title | Examining the role of red background in magnocellular contribution to face perception | Type | Journal Article | ||
| Year | 2016 | Publication | PeerJ | Abbreviated Journal | PeerJ |
| Volume | 4 | Issue | Pages | e1617 | |
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| Abstract | This study examines the role of the magnocellular system in the early stages of face perception, in particular sex categorization. Utilizing the specific property of magnocellular suppression in red light, we investigated visually guided reaching to low and high spatial frequency hybrid faces against red and grey backgrounds. The arm movement curvature measure shows that reduced response of the magnocellular pathway interferes with the low spatial frequency component of face perception. This finding provides behavioral evidence for magnocellular contribution to non-emotional aspect of face perception. | ||||
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| Language | en | Summary Language | Original Title | ||
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| ISSN | 2167-8359 | ISBN | Medium | ||
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| Notes |
Approved | no | |||
| Call Number | Serial | 81 | |||
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