Reflexes
Measure your reaction time with visual and audio stimuli
Author:
Title 4
Learning objectives :
This activity allows students to compare human reaction times to sound stimuli depending on whether the eyes are open or closed. It develops the understanding of sensory and motor mechanisms and the notion of measurement precision.
Concepts covered
Reaction time; Auditory and visual reflexes; Sensory integration; Measurement accuracy; Human nervous system
What students will do :
The student compares a manual stopwatch and a FizziQ acoustic stopwatch to measure the time elapsed between two hand claps. By starting the manual stopwatch at the first clap and stopping it at the second (while the acoustic stopwatch is triggered automatically) the student can evaluate their reaction time and then repeat the experiment with their eyes closed to compare the influence of visual and auditory stimuli on their reflexes.
What is required :
Two smartphones including at least one with the FizziQ application; Manual stopwatch on one of the smartphones; A calm environment; A partner to perform the snaps; FizziQ experience notebook
Scientific background :
Human reaction time is the delay between a stimulus and the onset of a voluntary response. This delay includes several stages: detection of the stimulus by sensory receptors, transmission of the nerve signal to the brain, processing of information, decision-making, and transmission of the motor command to the muscles concerned. Reaction times vary considerably depending on several factors: the type of stimulus (visual, auditory, tactile), age, fatigue, attention, and even the complexity of the required response. Typically, auditory reflexes (150-180 ms) are faster than visual reflexes (180-200 ms), because the processing of sound signals involves fewer neurological steps than that of visual signals. The comparison between the manual stopwatch and the FizziQ acoustic stopwatch makes it possible to precisely measure this reaction time. The acoustic stopwatch, triggered automatically by sound, represents "perfect" measurement with no reaction time, while the manual stopwatch includes human processing time. The difference between the two measurements therefore corresponds to the user's reaction time. By repeating the experiment with eyes closed, we can observe whether the deprivation of visual information modifies performance. Paradoxically, some people react more quickly with their eyes closed, because the absence of visual distractions allows better concentration on the auditory stimulus. This experiment also illustrates the notion of multimodal processing of sensory information: the brain simultaneously integrates information from different senses to optimize its responses. In emergency situations, this integration is crucial to minimize reaction time and can make the difference between avoiding or suffering an accident.