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Reaction Time: The time from the onset of a stimulus until a response is observed.

Measuring Reaction Time and Donders' Method of Subtraction

JoVE 10087

Source: Laboratory of Jonathan Flombaum—Johns Hopkins University

The ambition of experimental psychology is to characterize the mental events that support the human ability to solve problems, perceive the world, and turn thoughts into words and sentences. But people cannot see or feel those mental events; they cannot be weighed, combined in test tubes, or grown in a dish. Wanting to study mental life, nonetheless, Franciscus Donders, a Dutch ophthalmologist in the early 1800s, came up with a property that he could measure—even back then: he measured the time it took for human subjects to perform simple tasks, reasoning that he could treat those measurements as proxies for the time it takes to complete the unobservable mental operations involved. In fact, Donders went one step further, developing a basic experimental paradigm known as the Method of Subtraction. It simply asks a researcher to design two tasks that are identical in nearly every way, excepting a mental operation hypothesized to be involved in one of the tasks and omitted in the other. The researcher then measures the time it takes to complete each task, and by subtracting the outcomes, he extracts an estimate of the time it takes to execute the one mental operation of interest. In this way, the method allows a researcher


 Cognitive Psychology

Ligand-Mediated Nucleation and Growth of Palladium Metal Nanoparticles

1Department of Chemical Engineering, Virginia Polytechnic Institute and State University, 2Center for Integrated Nanotechnologies, Los Alamos National Laboratory, 3Advanced Photon Source, Argonne National Laboratory, 4X-ray Science Division, Argonne National Laboratory, 5Environmental Molecular Science Laboratory, Pacific Northwest National Laboratory

Video Coming Soon

JoVE 57667


 JoVE In-Press

Vision Training Methods for Sports Concussion Mitigation and Management

1Neurology and Rehabilitative Medicine, University of Cincinnati, 2Division of Sports Medicine, Department of Orthopaedic Surgery, University of Cincinnati, 3Department of Athletics, University of Cincinnati, 4Department of Neurosurgery, University of Cincinnati, 5College of Education, Criminal Justice, and Human Services, University of Cincinnati, 6Division of Sports Medicine, Cincinnati Children's Hospital Medical Center

JoVE 52648


 Behavior

Site-Directed Immobilization of Bone Morphogenetic Protein 2 to Solid Surfaces by Click Chemistry

1Fraunhofer-Institut für Grenzflächen- und Bioverfahrenstechnik (IGB), Translationszentrum Würzburg 'Regenerative Therapien für Krebs- und Muskuloskelettale Erkrankung', Institutsteil Würzburg, 2Lehrstuhl für Tissue Engineering und Regenerative Medizin, Universitätsklinikum Würzburg, 3Lehrstuhl für Pharmazeutische Technologie und Biopharmazie, Universität Würzburg, 4Lehrstuhl für molekulare Pflanzenphysiologie und Biophysik, Julius-von-Sachs Institut für Biowissenschaften, Universität Würzburg

JoVE 56616


 Bioengineering

PTR-ToF-MS Coupled with an Automated Sampling System and Tailored Data Analysis for Food Studies: Bioprocess Monitoring, Screening and Nose-space Analysis

1Department of Food Quality and Nutrition, Research and Innovation Centre, Fondazione Edmund Mach (FEM), 2Faculty of Science and Technology, Free University of Bolzano, 3Department of Agriculture, Food and Environmental Sciences, University of Foggia, 4Institute of Analytical Chemistry & Radiochemistry, Leopold-Franzens Universität Innsbruck, 5Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens Universität Innsbruck

JoVE 54075


 Chemistry

Kinetics of Addition Polymerization to Polydimethylsiloxane

JoVE 10369

Source: Kerry M. Dooley and Michael G. Benton, Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA

Polymers are molecules consisting of many repeating monomer units that are chemically bonded into long chains. They exhibit a broad range of physical properties, which are affected by their chemical structure, molecular weight and degree of polymerization. The polymer industry manufactures thousands of raw materials used in a broad variety of commercial products.1,2 The goal of this video is to perform an addition polymerization reaction and then evaluate the resulting product to understand how viscosity can be used to determine polymer molecular weight. Additionally, this experiment will investigate how molecular weight can be related to monomer conversion.


 Chemical Engineering

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