The notion of multiple memory systems based on conscious accessibility has been supported largely by neuropsychological patient studies. Specifically, it was widely held that amnesic patients have impaired explicit memory performance but spared implicit memory performance. However, recent patient studies have called the implicit͞explicit memory distinction into question. In this study, normal participants were tested on a visual search task, once after an injection of midazolam, an anesthetic that induces temporary amnesia, and once after an injection of saline. Under the influence of midazolam, participants did not show facilitation in search times for repeated configurations (contextual cuing), although there was a general speed-up in performance across blocks in both the midazolam and saline conditions. Neither the contextual-cuing effect nor the procedural-learning effect was available to subjective experience, yet only one of these was affected by midazolam-induced amnesia. These data call into question the notion that memory systems divide on the basis of subjective experience of consciousness or reportability. Rather, the findings support the contention that anterograde amnesia affects learning that depends on building novel associations in memory and that this deficit does not hinge upon accessibility to consciousness. explicit memory ͉ implicit memory ͉ synthetic amnesia

Midazolam is a drug that creates temporary anterograde amnesia. In a within-subjects, doubleblind experiment, participants studied a list of stimuli after receiving an injection of midazolam in one session and after receiving saline in another session. The lists consisted of three types of stimuli: words, photographs, and abstract pictures. Recognition memory was tested at the end of each session. Memory was reliably poorer in the midazolam condition than the saline condition, but this amnesic effect was significantly smaller for pictorial stimuli than for words and almost nonexistent for abstract pictures. We argue that the less familiar the stimulus, the less likely it is to be associated with an experimental context. These data bolster our claim that unitization increases the chances of episodic binding and that drug-induced amnesia prevents episodic binding regardless of unitization.There is evidence that recognition can be based on either the retrieval of episodic information or the backup process of familiarity (Diana,