Simple reaction time: it is not what it used to be

Area of Science:

• Psychology
• Human Physiology
• Environmental Health

Background:

• Reaction time (RT) is a fundamental measure of cognitive processing speed.
• Historical data suggests potential changes in human cognitive performance over time.
• Understanding secular trends in RT is crucial for public health and cognitive science.

Purpose of the Study:

• To investigate whether simple visual reaction time (RT) has increased in young adults over the past century.
• To compare RT data from contemporary studies with historical data from the late 1800s.
• To explore potential environmental and health-related factors contributing to observed changes in RT.

Main Methods:

• Comparative analysis of RT data from 14 studies published from 1941 onwards.
• Comparison of contemporary RT data with RT measurements from a study conducted by Galton in the late 1800s.
• Evaluation of potential confounding factors such as timing instrument accuracy.

Main Results:

• With one exception, studies published from 1941 onwards reported longer simple visual reaction times (RTs) compared to Galton's late 1800s data.
• Differences in timing instruments were considered but found unlikely to explain the observed increase in RT.
• The data indicates a significant secular trend towards slower simple visual reaction times.

Conclusions:

• Evidence suggests a substantial increase in simple visual reaction time (RT) among young adults over the last century.
• Potential contributing factors to increased RT include environmental neurotoxin accumulation and improved survival rates of individuals with poorer health.
• Standardization of RT testing protocols is recommended for more precise analysis of secular trends.