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A stroke engine has a slider-crank mechanism that converts rotational motion from the crank into linear motion of the slider or vice versa. This mechanism consists of three main parts: the crank, the connecting rod, and the slider.
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Ensemble coding of crowd speed using biological motion.

Tram T N Nguyen1,2, Quoc C Vuong3, George Mather4

  • 1Department of Cognitive Science, Faculty of Media and Knowledge Sciences, University of Malta, Msida, Malta. tram.nguyen@um.edu.mt.

Attention, Perception & Psychophysics
|November 10, 2020
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Summary
This summary is machine-generated.

Perceiving crowd speed is fast and accurate, especially for quicker movements, even with limited viewing time. Slower crowds are harder to estimate accurately as viewing duration decreases.

Keywords:
Biological motionEnsemble codingSpeed perception

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Area of Science:

  • Cognitive psychology
  • Visual perception
  • Social cognition

Background:

  • Accurate perception of human crowds is crucial for social understanding.
  • Previous research identified sensitivity to crowd characteristics like expression, gender, and heading direction.

Purpose of the Study:

  • To investigate ensemble perception of crowd speed using point-light walkers (PLW).
  • To determine how viewing duration affects the estimation of average crowd speed.

Main Methods:

  • Two experiments were conducted with participants estimating the average speed of 12 PLWs moving at different speeds.
  • Experiment 1 compared intact and scrambled PLWs over 3 seconds.
  • Experiment 2 varied viewing durations (2500 ms to 500 ms) for intact PLW crowds.

Main Results:

  • Ensemble speed perception can utilize local motion, enhanced by globally intact configurations.
  • Fast crowds were estimated accurately regardless of viewing duration; 3-4 walkers integrated at 500 ms.
  • Slow crowd speed estimation deteriorated significantly with reduced viewing time, becoming indistinguishable from single-walker performance at 500 ms.

Conclusions:

  • Rapid and accurate ensemble perception of crowd speed is possible.
  • Performance is sensitive to the specific speed range of the crowd.
  • Limited viewing durations disproportionately impact the perception of slower crowds.