The effect of D-amphetamine and caffeine on WM
As there are no one generally accepted model to measure WM [In the present study, we used DST and SST to measure VWM and SWM, respectively. The DST is a simple span tasks used to measure auditory WM. SST is comparatively more complex tasks [We failed to find a main effect of d-amphetamine on SWM, which is in agreement or comparable with previous studies on the SWM effect of d-amphetamine in various SWM task performances [Although we used higher doses than previous studies that assessed the effect of d-amphetamine on SWM, we failed to find main effects of d-amphetamine on SST performance. In addition, we applied four delay conditions in order to examine the maintenance component of WM, but the results showed that d-amphetamine did not influence WM in the presence of delays. A previous study [The present result also showed that d-amphetamine does not affect VWM on the DST under four delay conditions, which is in agreement with previous studies that used backward DST, forward DST or both to assess VWM [With respect to caffeine, the present finding is consistent with previous reports on the acute effects of caffeine on SWM (n-back test) [