Coffee time: Caffeine improves reaction to moving targets
University of Waterloo
In the first study of its kind to explore caffeine's effects on dynamic visual skills, researchers concluded that caffeine increases alertness and detection accuracy for moving targets. Caffeine also improved participants' reaction times.
"A lot of what happens in our environment is moving -- like trying to cross a busy intersection as a pedestrian or finding something on a shelf as you're walking through the aisles of a grocery store," said Dr. Kristine Dalton of Waterloo's School of Optometry & Vision Science.
"Testing visual
acuity under dynamic conditions can provide more information about our
functional performance in these scenarios than traditional static visual acuity
measurements alone."
Visual acuity, also known as clarity of vision or sharpness of vision, refers to a person's ability to detect and recognize small details and can be measured under static (stationary) or dynamic (moving) conditions.
While both static and
dynamic visual acuity provide important information about how we interact with
the world around us, dynamic visual acuity skills are especially important in
the many daily activities in which we, or objects around us are moving.
"While we already know that caffeine increases the velocity of rapid-eye movements, we wanted to further investigate how exactly caffeine enhances visual processing and facilitates the detection of moving visual stimuli by testing dynamic visual acuity," said co-author Beatríz Redondo of the University of Granada's Department of Optics.
On
two separate days, half of the study's participants ingested a caffeine capsule
(4mg/kg) while the other half ingested a placebo capsule. Using a
computer-based test designed and validated at the University of Waterloo, each
participant's dynamic visual acuity skills were measured before and 60 minutes
after caffeine ingestion.
Researchers
found that participants who had ingested the caffeine capsules showed
significantly greater accuracy and faster speed when identifying smaller moving
stimuli, inferring caffeine positively influences participants' stimulus
processing and decision-making. Eye movement velocity and contrast sensitivity,
which are implicated in dynamic visual acuity performance, were also sensitive
to caffeine intake.
"Our
findings show that caffeine consumption can actually be helpful for a person's
visual function by enhancing alertness and feelings of wakefulness,"
Dalton said. "This is especially true for those critical, everyday tasks,
like driving, riding a bike or playing sports, that require us to attend to
detailed information in moving objects when making decisions."
The
study, Effects of caffeine ingestion on dynamic visual acuity, co-authored by
Waterloo's School of Optometry & Vision Science's Dalton, and the
University of Granada's Redondo, Raimundo Jiménez, Rubén Molina and Jesús Vera,
was recently published in the Psychopharmacology journal.