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Thorsten Plewan - One of the best experts on this subject based on the ideXlab platform.
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Simple Reaction time and size–distance integration in virtual 3D space
Psychological Research, 2017Co-Authors: Thorsten Plewan, Gerhard RinkenauerAbstract:Simple Reaction time to visual stimuli depends on several stimulus properties. Recently, converging evidence showed that larger stimulus size evokes faster Reactions and that this effect seemingly depends on the stimulus’ perceived size rather than on physical stimulus properties. Size–distance scaling usually is regarded as the main functional mechanism underlying size perception. Yet, the role of stimulus depth (distance to a target) has often been neglected in previous studies. Hence, in the present investigation, stimuli were generated using stereo head mounted displays to manipulate stimulus depth. In Experiment 1, a large or small target was presented within the center of a reference plane, either in the same depth plane or displaced (near, far) while participants had to perform a Simple Reaction time task. At the same time, the target was modulated such that either retinal size was constant or variable across depth planes. In Experiments 2 and 3 the reference plane was shifted along with the target (blocked or on a trial-by-trial basis), while retinal size modulation was equal to Experiment 1. As expected, participants reacted faster to physically larger targets. Also Experiment 1 revealed faster Reaction times for closer targets, while the commonly described connection between perceived size (i.e., size–distance scaling) was not apparent in any experiment. Thus, unlike past findings using a virtual three-dimensional task-setting (as induced by binocular disparity) Reaction times are not affected by variations of perceived stimulus size.
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Simple Reaction time and size-distance integration in virtual 3D space.
Psychological research, 2016Co-Authors: Thorsten Plewan, Gerhard RinkenauerAbstract:Simple Reaction time to visual stimuli depends on several stimulus properties. Recently, converging evidence showed that larger stimulus size evokes faster Reactions and that this effect seemingly depends on the stimulus’ perceived size rather than on physical stimulus properties. Size–distance scaling usually is regarded as the main functional mechanism underlying size perception. Yet, the role of stimulus depth (distance to a target) has often been neglected in previous studies. Hence, in the present investigation, stimuli were generated using stereo head mounted displays to manipulate stimulus depth. In Experiment 1, a large or small target was presented within the center of a reference plane, either in the same depth plane or displaced (near, far) while participants had to perform a Simple Reaction time task. At the same time, the target was modulated such that either retinal size was constant or variable across depth planes. In Experiments 2 and 3 the reference plane was shifted along with the target (blocked or on a trial-by-trial basis), while retinal size modulation was equal to Experiment 1. As expected, participants reacted faster to physically larger targets. Also Experiment 1 revealed faster Reaction times for closer targets, while the commonly described connection between perceived size (i.e., size–distance scaling) was not apparent in any experiment. Thus, unlike past findings using a virtual three-dimensional task-setting (as induced by binocular disparity) Reaction times are not affected by variations of perceived stimulus size.
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the influence of stimulus duration on visual illusions and Simple Reaction time
Experimental Brain Research, 2012Co-Authors: Thorsten Plewan, Ralph Weidner, Gereon R FinkAbstract:Target detection is affected by stimulus intensity. For instance, participants respond faster to larger objects than to smaller objects. In order to compute an object’s size, the brain integrates contextual information, for example object distance. Accordingly, the perceived size of an object can be altered via depth cues which modulate perceived object distance. Recently, it has been demonstrated that Reaction times are influenced by the perceived rather than by the retinal size of an object, thus indicating that manual responses are generated after the perceptual integration of distance and retinal size. However, the timing aspects of these integration processes to date remain largely unclear. Therefore, the present study investigated the influence of stimulus duration on size–distance integration by means of a Simple Reaction time paradigm and the well-known Ponzo illusion. In experiment 1, participants responded faster to perceptually longer lines within an illusion-inducing background, whereas no such effect was associated with a neutral background. Experiment 2 revealed that this effect depended on stimulus duration. Stimuli were reliably perceived even with the shortest durations. However, illusion-induced modulations of response times were not observed for stimulus durations shorter than 40 ms. The findings indicate that the integration of context and object information requires visual input to last for at least 40 ms. The data furthermore show that as long as the visual system has not enough time to integrate context and object information, size perception is formed on the basis of lower-level representations.
Gerhard Rinkenauer - One of the best experts on this subject based on the ideXlab platform.
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Simple Reaction time and size–distance integration in virtual 3D space
Psychological Research, 2017Co-Authors: Thorsten Plewan, Gerhard RinkenauerAbstract:Simple Reaction time to visual stimuli depends on several stimulus properties. Recently, converging evidence showed that larger stimulus size evokes faster Reactions and that this effect seemingly depends on the stimulus’ perceived size rather than on physical stimulus properties. Size–distance scaling usually is regarded as the main functional mechanism underlying size perception. Yet, the role of stimulus depth (distance to a target) has often been neglected in previous studies. Hence, in the present investigation, stimuli were generated using stereo head mounted displays to manipulate stimulus depth. In Experiment 1, a large or small target was presented within the center of a reference plane, either in the same depth plane or displaced (near, far) while participants had to perform a Simple Reaction time task. At the same time, the target was modulated such that either retinal size was constant or variable across depth planes. In Experiments 2 and 3 the reference plane was shifted along with the target (blocked or on a trial-by-trial basis), while retinal size modulation was equal to Experiment 1. As expected, participants reacted faster to physically larger targets. Also Experiment 1 revealed faster Reaction times for closer targets, while the commonly described connection between perceived size (i.e., size–distance scaling) was not apparent in any experiment. Thus, unlike past findings using a virtual three-dimensional task-setting (as induced by binocular disparity) Reaction times are not affected by variations of perceived stimulus size.
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Simple Reaction time and size-distance integration in virtual 3D space.
Psychological research, 2016Co-Authors: Thorsten Plewan, Gerhard RinkenauerAbstract:Simple Reaction time to visual stimuli depends on several stimulus properties. Recently, converging evidence showed that larger stimulus size evokes faster Reactions and that this effect seemingly depends on the stimulus’ perceived size rather than on physical stimulus properties. Size–distance scaling usually is regarded as the main functional mechanism underlying size perception. Yet, the role of stimulus depth (distance to a target) has often been neglected in previous studies. Hence, in the present investigation, stimuli were generated using stereo head mounted displays to manipulate stimulus depth. In Experiment 1, a large or small target was presented within the center of a reference plane, either in the same depth plane or displaced (near, far) while participants had to perform a Simple Reaction time task. At the same time, the target was modulated such that either retinal size was constant or variable across depth planes. In Experiments 2 and 3 the reference plane was shifted along with the target (blocked or on a trial-by-trial basis), while retinal size modulation was equal to Experiment 1. As expected, participants reacted faster to physically larger targets. Also Experiment 1 revealed faster Reaction times for closer targets, while the commonly described connection between perceived size (i.e., size–distance scaling) was not apparent in any experiment. Thus, unlike past findings using a virtual three-dimensional task-setting (as induced by binocular disparity) Reaction times are not affected by variations of perceived stimulus size.
Aliakbar Akbarzadeh - One of the best experts on this subject based on the ideXlab platform.
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Performance Investigation of a Simple Reaction Water Turbine for Power Generation from Low Head Micro Hydro Resources
Smart Grid and Renewable Energy, 2012Co-Authors: Abhijit Date, Ashwin Date, Aliakbar AkbarzadehAbstract:Theoretical investigation has shown a Simple Reaction water turbine would perform better when it spins faster. And for the Simple Reaction turbine water turbine to spin faster under constant water head, its diameter should be smaller. This paper reports on a performance analysis based on the experimental data collected from different performance tests carried on two Simple Reaction water turbine prototypes. Two new designs of Simple Reaction water turbines and their manufacturing methods are reported. The two turbines under investigation have different rotor diameters Φ 0.243 m and Φ 0.122 m. In case of the Simple Reaction water turbine the water enters into the turbine axially and exits tangentially through nozzles located on the outer periphery of the turbine. Further this paper will discuss the performance characteristics of stationary turbine i.e. zero power produced and performance characteristics of turbine producing power. It was found that rotor diameter affects the maximum rotational speed of the Simple Reaction turbine for constant supply head. It was also found that faster the turbine spins its performance improves. The two turbines were tested between supply head range of 1 m to 4 m
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design and cost analysis of low head Simple Reaction hydro turbine for remote area power supply
Renewable Energy, 2009Co-Authors: Abhijit Date, Aliakbar AkbarzadehAbstract:This paper is aimed at exploring the performance characteristics of a Simple Reaction hydro turbine for power generation. Using principles of conservation of mass, momentum and energy, the governing equations have been identified for an ideal case of no frictional losses. The paper also describes the conception of a cross-pipe rotor for remote area electricity production. Using the ideal governing equations an optimized geometry of the rotor was selected for the working head of 5 m. Theoretical analysis of the self-governing characteristics has been presented. Experiments were carried out for 2, 3, 4 and 5 m head and evaluated against theoretical results. Split pipe turbine model is presented with detail layout, while different methods of experimentation are explored for different output requirements with varied heads. Various losses in the system are discussed, quantified and included in the graphical format. It is also demonstrated that the experimental power outputs do not have the same tendencies as theoretical predictions and decreases due to jet interference beyond a certain rotational speed as it passes the maximum power point.
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Design Analysis and Investigation of a Low-Head Simple Reaction Water Turbine
2005Co-Authors: Abhijit Date, Aliakbar AkbarzadehAbstract:Performance characteristics of low-head Simple Reaction water turbine are investigated in this paper. A new low-cost low-head Simple Reaction turbine design is proposed. A Simple approach is proposed to overcome the runaway and jet interference problem of the Simple Reaction turbine. Optimal design criteria have been established based on results from a computer model of a Simple Reaction water turbine for different operating conditions. Experimental results have been analysed and compared with theoretical predictions. The experimental data give a good quantitative description of the turbine characteristics. The test results included in this article are for a supply condition of 5 metre head and flow rates of 1 to 2 litres/sec.
Mark Hallett - One of the best experts on this subject based on the ideXlab platform.
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A shared neural network for Simple Reaction time.
NeuroImage, 2004Co-Authors: Kenji Kansaku, Takashi Hanakawa, Mark HallettAbstract:Simple Reaction time, a Simple model of sensory-to-motor behavior, has been extensively investigated and its role in inferring elementary mental organization has been postulated. However, little is known about the neuronal mechanisms underlying it. To elucidate the neuronal substrates, functional magnetic resonance imaging (fMRI) signals were collected during a Simple Reaction task paradigm using Simple cues consisting of different modalities and Simple triggered movements executed by different effectors. We hypothesized that a specific neural network that characterizes Simple Reaction time would be activated irrespective of the input modalities and output effectors. Such a neural network was found in the right posterior superior temporal cortex, right premotor cortex, left ventral premotor cortex, cerebellar vermis, and medial frontal gyrus. The right posterior superior temporal cortex and right premotor cortex were also activated by different modality sensory cues in the absence of movements. The shared neural network may play a role in sensory triggered movements.
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effects of focal transcranial magnetic stimulation on Simple Reaction time to acoustic visual and somatosensory stimuli
Brain, 1992Co-Authors: Alvaro Pascualleone, Josep Vallssole, Eric M Wassermann, J P Brasilneto, Leonardo G Cohen, Mark HallettAbstract:In a Simple Reaction time (RT) paradigm, magnetic stimulation of different intensities was delivered over different scalp positions and at variable delays before (negative) or after (positive) the go-signal. Magnetic stimulation shortened RT to different go-signals (auditory, visual and somatosensory stimuli) by approximately 30 ms when delivered over the motor cortex contralateral to the responding arm at intensities below motor threshold. This effect was maximal at a delay of approximately + 10 ms. A similar effect was found with suprathreshold stimulation to the ipsilateral motor cortex. Magnetic stimulation over other scalp areas did not affect RT regardless of the delay. No differences were found between the effects on elbow flexion and thumb abduction. The shortening of RT was not associated with changes in the timing development of premovement excitability increase in the motor cortex. We conclude that magnetic stimulation shortens RT by inducing an earlier initiation of this excitability increase
Alvaro Pascualleone - One of the best experts on this subject based on the ideXlab platform.
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akinesia in parkinson s disease i shortening of Simple Reaction time with focal single pulse transcranial magnetic stimulation
Neurology, 1994Co-Authors: Alvaro Pascualleone, J Vallssole, J P Asilneto, L G Cohe, M HalleAbstract:Article abstract –We studied the effects of transcranial magnetic stimulation (TMS) of the motor cortex on Simple Reaction time (RT) in 10 patients with Parkinson9s disease compared with 10 age-matched normal controls. The subjects flexed their right elbow rapidly in response to a visual go-signal. In random trials, TMS was applied to the left motor cortex at varying delays after the go-signal. In trials without TMS, RT was longer in the patients. However, in the trials with subthreshold TMS, RT in the patients became as fast as RT in trials without TMS in the controls. This shortening was associated with normalization of the voluntary triphasic EMG pattern and the pre-movement cortical excitability increase.
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effects of focal transcranial magnetic stimulation on Simple Reaction time to acoustic visual and somatosensory stimuli
Brain, 1992Co-Authors: Alvaro Pascualleone, Josep Vallssole, Eric M Wassermann, J P Brasilneto, Leonardo G Cohen, Mark HallettAbstract:In a Simple Reaction time (RT) paradigm, magnetic stimulation of different intensities was delivered over different scalp positions and at variable delays before (negative) or after (positive) the go-signal. Magnetic stimulation shortened RT to different go-signals (auditory, visual and somatosensory stimuli) by approximately 30 ms when delivered over the motor cortex contralateral to the responding arm at intensities below motor threshold. This effect was maximal at a delay of approximately + 10 ms. A similar effect was found with suprathreshold stimulation to the ipsilateral motor cortex. Magnetic stimulation over other scalp areas did not affect RT regardless of the delay. No differences were found between the effects on elbow flexion and thumb abduction. The shortening of RT was not associated with changes in the timing development of premovement excitability increase in the motor cortex. We conclude that magnetic stimulation shortens RT by inducing an earlier initiation of this excitability increase
