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Updated: May 26, 2026
Infant Auditory Processing and Event-related Brain Oscillations
Published on: July 1, 2015
Speed discrimination in 6- and 10-month-old infants follows Weber's law
Wenke Möhring1, Melissa E Libertus, Evelyn Bertin
1Department of Psychology, Cognitive and Developmental Psychology, University of Zurich, 8050 Zurich, Switzerland. w.moehring@psychologie.uzh.ch
Insights
Infants develop speed discrimination abilities early in life. Ten-month-olds can distinguish speeds with a 2:3 ratio, while six-month-olds can only discriminate larger speed differences.
Area of Science:
- Developmental Psychology
- Perception Science
- Cognitive Neuroscience
Background:
- The ability to perceive object speed is crucial for everyday actions.
- The developmental trajectory of speed discrimination in infants remains largely unexplored.
Purpose of the Study:
- To investigate the age at which infants develop the ability to discriminate between different object speeds.
- To determine the precision of speed discrimination in infants at different developmental stages.
Main Methods:
- A habituation paradigm was employed with 6- and 10-month-old infants.
- Infants were presented with visual stimuli of a ball rolling at various speeds.
- Looking times were measured to assess discrimination between familiar and novel speeds.
Main Results:
- Six-month-old infants discriminated speeds with a 1:2 ratio but not a 2:3 ratio.
- Ten-month-old infants successfully discriminated speeds with a 2:3 ratio.
- Speed discrimination in both age groups followed Weber's law, indicating ratio-dependent perception.
Conclusions:
- Infants' ability to discriminate object speed develops significantly between 6 and 10 months of age.
- These findings suggest a shared perceptual system for processing different magnitudes, including speed, duration, size, and number.
- Early developing magnitude processing systems may support complex cognitive functions later in life.
Abstract:
The speed of a moving object is a critical variable that factors into actions such as crossing a street and catching a ball. However, it is not clear when the ability to discriminate between different speeds develops. Here, we investigated speed discrimination in 6- and 10-month-old infants using a habituation paradigm showing infants events of a ball rolling at different speeds. The 6-month-olds looked longer at novel speeds that differed by a 1:2 ratio than at the familiar ones but showed no difference in looking time to speeds that differed by a 2:3 ratio. In contrast, the 10-month-olds succeeded at discriminating a 2:3 ratio. For both age groups, discrimination was modulated by the ratio between novel and familiar speeds, suggesting that speed discrimination is subject to Weber's law. These findings show striking parallels to previous results in infants' discrimination of duration, size, and number and suggest a shared system for processing different magnitudes.
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