Lane, S. D., Cherek, D. R., Lieving, L. M., & Tcheremissine, O. V. (2005).
Marijuana effects on human forgetting functions.
Journal of the Experimental Analysis of Behavior, 83, 67-83.
It has long been known that acute marijuana administration impairs
working memory (e.g., the discrimination of stimuli separated by a delay).
The determination of which of the individual components of memory are
altered by marijuana is an unresolved problem. Previous human studies
did not use test protocols that allowed for the determination
of delay-independent (initial discrimination) from delay-dependent
(forgetting or retrieval) components of memory. Using methods
developed in the experimental analysis of behavior and signal
detection theory, we tested the acute effects of smoked marijuana
on forgetting functions in 5 humans. Immediately after smoking
placebo, a low dose, or a high dose of marijuana (varying in delta9-THC content),
subjects completed delayed match-to-sample testing that included a range
of retention intervals within each test session (0.5, 4, 12, and 24 s).
Performances (discriminability) at each dose were plotted as forgetting
functions, as described and developed by White and colleagues
(White, 1985; White & Ruske, 2002). For all 5 subjects, both delta9-THC
doses impaired delay-dependent discrimination but not
delay-independent discrimination. The outcome is consistent
with current nonhuman studies examining the role of the
cannabinoid system on delayed matching procedures, and the
data help illuminate one behavioral mechanism through which
marijuana alters memory performance.
Key words: marijuana, delayed match-to-sample, memory, human