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| Author | Awasthi, Bhuvanesh; Friedman, Jason; Williams, Mark A | ||||
| Title | Processing of low spatial frequency faces at periphery in choice reaching tasks | Type | Journal Article | ||
| Year | 2011 | Publication | Neuropsychologia | Abbreviated Journal | |
| Volume | 49 | Issue | 7 | Pages | 2136-2141 |
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| Abstract | Various aspects of face processing have been associated with distinct ranges of spatial frequencies. Configural processing of faces depends chiefly on low spatial frequency (LSF) information whereas high spatial frequency (HSF) supports feature based processing. However, it has also been argued that face processing has a foveal-bias (HSF channels dominate the fovea). Here we used reach trajectories as a continuous behavioral measure to study perceptual processing of faces. Experimental stimuli were LSF–HSF hybrids of male and female faces superimposed and were presented peripherally and centrally. Subject reached out to touch a specified sex and their movements were recorded. The reaching trajectories reveal that there is less effect of (interference by) LSF faces at fovea as compared to periphery while reaching to HSF targets. These results demonstrate that peripherally presented LSF information, carried chiefly by magnocellular channels, enables efficient processing of faces, possibly via a retinotectal (subcortical) pathway. | ||||
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| Notes | Approved | no | |||
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Serial | 24 | |||
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| Author | Friedman, J.; Korman, M. | ||||
| Title | Kinematic Strategies Underlying Improvement in the Acquisition of a Sequential Finger Task with Self-Generated vs. Cued Repetition Training | Type | Journal Article | ||
| Year | 2012 | Publication | PLoS one | Abbreviated Journal | PLoS One |
| Volume | 7 | Issue | 12 | Pages | e52063 |
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| Abstract | Many motor skills, such as typing, consist of articulating simple movements into novel sequences that are executed faster and smoother with practice. Dynamics of re-organization of these movement sequences with multi-session training and its dependence on the amount of self-regulation of pace during training is not yet fully understood. In this study, participants practiced a sequence of key presses. Training sessions consisted of either externally (Cued) or self-initiated (Uncued) training. Long-term improvements in performance speed were mainly due to reducing gaps between finger movements in both groups, but Uncued training induced higher gains. The underlying kinematic strategies producing these changes and the representation of the trained sequence differed significantly across subjects, although net gains in speed were similar. The differences in long-term memory due to the type of training and the variation in strategies between subjects, suggest that the different neural mechanisms may subserve the improvements observed in overall performance. | ||||
| Address | Department of Cognitive Science, Macquarie University, Sydney, Australia ; ARC Centre of Excellence in Cognition and its Disorders, Macquarie University, Sydney, Australia | ||||
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| Language | English | Summary Language | Original Title | ||
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| ISSN | 1932-6203 | ISBN | Medium | ||
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| Notes | PMID:23272210 | Approved | no | ||
| Call Number |
Serial | 41 | |||
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| Author | Awasthi, B.; Sowman, P.F.; Friedman, J.; Williams, M.A. | ||||
| Title | Distinct spatial scale sensitivities for early categorisation of Faces and Places: Neuromagnetic and Behavioural Findings | Type | Journal Article | ||
| Year | 2013 | Publication | Frontiers in Human Neuroscience | Abbreviated Journal | |
| Volume | 7 | Issue | 91 | Pages | |
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| Abstract | Research exploring the role of spatial frequencies in rapid stimulus detection and categorisation report flexible reliance on specific spatial frequency bands. Here, through a set of behavioural and magnetoencephalography (MEG) experiments, we investigated the role of low spatial frequency (LSF)(25 cpf) information during the categorisation of faces and places. Reaction time measures revealed significantly faster categorisation of faces driven by LSF information, while rapid categorisation of places was facilitated by HSF information. The MEG study showed significantly earlier latency of the M170 component for LSF faces compared to HSF faces. Moreover, the M170 amplitude was larger for LSF faces than for LSF places, whereas the reverse pattern was evident for HSF faces and places. These results suggest that spatial frequency modulates the processing of category specific information for faces and places. | ||||
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| ISSN | 1662-5161 | ISBN | Medium | ||
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| Notes | Approved | no | |||
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Serial | 67 | |||
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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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| Notes | Approved | no | |||
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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 | ||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number |
Serial | 73 | |||
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