idw – Informationsdienst Wissenschaft
Nachrichten, Termine, Experten
Nachrichten, Termine, Experten
Energetic expenditure not the only factor when judging physical effort of movements
Scientists from the German Primate Center, led by Pierre Morel, have determined which characteristics of an arm movement influence the subjective effort associated with this movement. In a study publishing on June 6 they found that duration, biomechanics and force had an influence on the effort, while movement amplitudes had no effect. Their results argue against a minimization of pure energetic costs. They also shed light on a postulated link between two important functions of the brain: optimizing action selection in decision-making and in movement execution (PLOS Biology).
When choosing between alternative actions, we have to compare the positive outcomes of those actions and weigh them against their costs. Whether a predator hunting prey, a monkey picking fruits, or a human wavering between stairs and elevator, the physical effort associated with executing an action is a relevant cost and hence a decision factor. Understanding how we estimate movement effort is thus necessary to understand how we take decisions.
To study physical effort, human subjects were asked to repeatedly choose between arm movements which differed in amplitude or duration and in force. Not surprisingly, effort increased with the strength of a force resisting the movement. The researchers managed to quantify this dependency precisely, showing that effort was proportional to the square of that strength. Additionally, effort was higher when the movements involved weaker muscles, even for movements that necessitated only little strength. More surprisingly, Morel and colleagues showed that the distance covered by the movements did not determine effort. Instead, effort depended on the duration of the movements, with movements that lasted longer feeling more strenuous than brief movements.
“Our results allow us to estimate action-related costs in decision-making, showing they cannot easily be predicted from energetic expense”, says Morel. “More than that, the results also give weight to the idea that action selection in decision-making and in movement execution have common properties and hence might be based on shared mechanisms.” When a given action is executed, its goal can typically be achieved in many ways. For example, the multiple joints of the arm provide a large flexibility in how we could conduct reaches to a given target object. Nevertheless, when repeating reaches towards the same target, we tend to execute them in the same optimized way. “We conclude that previously described optimization principles during movement execution seem to also serve as guiding principles during economically motivated conscious choice before movement execution”, says Alexander Gail, head of the research group. Understanding how we estimate movement effort is an important step towards understanding how we take decisions.
Original publication
Morel P, Ulbrich P, Gail A (2017) What makes a reach movement effortful? Physical effort discounting supports common minimization principles in decision making and motor control. PLoS Biol 15(6): e2001323. https://doi.org/10.1371/journal.pbio.2001323
Contact and notes for editors
Dr. Pierre Morel
Phone: + 49 551 3851-342
Email: pmorel@dpz.eu
Prof. Dr. Alexander Gail
Phone: + 49 551 3851-358
Email: agail@dpz.eu
Dr. Susanne Diederich (Communication)
Phone: +49 551 3851-359
Email: sdiederich@dpz.eu
Printable pictures are available in our Media library. We kindly request a specimen copy or a link in case of publication. The press release with further information can also be found on our website after the embargo has lifted.
The German Primate Center (DPZ) – Leibniz Institute for Primate Research conducts biological and biomedical research on and with primates in the fields of infection research, neuroscience and primate biology. The DPZ maintains four field stations in the tropics and is the reference and service center for all aspects of primate research. The DPZ is one of 91 research and infrastructure facilities of the Leibniz Association.
http://medien.dpz.eu/webgate/keyword.html?currentContainerId=3981 - Media library
http://www.dpz.eu
Test persons were repeatedly asked to move the handle of this experimental setup.
Image: Thomas Steuer/ Pierre Morel
None
Dr. Pierre Morel, scientist at the Sensorimotor Group, German Primate Center.
Image: Margrit Hampe
None
Merkmale dieser Pressemitteilung:
Journalisten, Wissenschaftler, jedermann
Biologie
überregional
Forschungsergebnisse, Wissenschaftliche Publikationen
Englisch
Test persons were repeatedly asked to move the handle of this experimental setup.
Image: Thomas Steuer/ Pierre Morel
None
Dr. Pierre Morel, scientist at the Sensorimotor Group, German Primate Center.
Image: Margrit Hampe
None
Sie können Suchbegriffe mit und, oder und / oder nicht verknüpfen, z. B. Philo nicht logie.
Verknüpfungen können Sie mit Klammern voneinander trennen, z. B. (Philo nicht logie) oder (Psycho und logie).
Zusammenhängende Worte werden als Wortgruppe gesucht, wenn Sie sie in Anführungsstriche setzen, z. B. „Bundesrepublik Deutschland“.
Die Erweiterte Suche können Sie auch nutzen, ohne Suchbegriffe einzugeben. Sie orientiert sich dann an den Kriterien, die Sie ausgewählt haben (z. B. nach dem Land oder dem Sachgebiet).
Haben Sie in einer Kategorie kein Kriterium ausgewählt, wird die gesamte Kategorie durchsucht (z.B. alle Sachgebiete oder alle Länder).
