Long-term effects of cannabis on eye movement control in reading.
BACKGROUND
Cannabis is known to produce substantial acute effects on human cognition and visuomotor skills. Many recent studies additionally revealed rather long-lasting effects on basic oculomotor control, especially after chronic use. However, it is still unknown to what extent these deficits play a role in everyday tasks that strongly rely on an efficient saccade system, such as reading.


METHODS
In the present study, eye movements during sentence reading of 20 healthy long-term cannabis users (without acute tetrahydrocannabinol-intoxication) and 20 control participants were compared. Analyses focused on both spatial and temporal parameters of oculomotor control during reading.


RESULTS
Long-term cannabis users exhibited increased fixation durations, more revisiting of previously inspected text, and a substantial prolongation of word viewing times, which were highly inflated for longer and less frequent words.


CONCLUSIONS
The results indicate that relatively subtle performance deficits on the level of basic oculomotor control scale up as task complexity and cognitive demands increase.
Huestegge
Lynn
L
Institute of Psychology, RWTH Aachen University, Jaegerstasse 17-19, 52056 Aachen, Germany. Lynn.Huestegge@psych.rwth-aachen.de
Kunert
Hanns-Jürgen
HJ
Radach
Ralph
R
D000328:Adult; D003071:Cognition / Q000187:drug effects; D005133:Eye Movements / Q000187:drug effects*; D005260:Female; D005403:Fixation, Ocular / Q000187:drug effects*; D006801:Humans; D008297:Male; D002189:Marijuana Abuse / Q000150:complications*; D008875:Middle Aged; D009801:Oculomotor Muscles / Q000187:drug effects; D011932:Reading; D013997:Time Factors; D055815:Young Adult