The effects of intravenous diazepam and hyoscine upon human memory

Diazepam and hyoscine are known to have amnesic effects when administered intravenously. The two drugs are pharmacologically quite different from each other and might be expected to produce qualitatively distinct patterns of impairment in formal memory tasks. Groups of normal volunteers received intravenous administrations of diazepam, hyoscine and saline following a double-blind procedure and were then tested on immediate serial recall. Diazepam and hyoscine produced similar deficits on concrete and abstract words whether scored for ordered recall or item recall. In terms of ordered recall, phonemic similarity produced impaired performance under all three administrations, but semantic similarity did not. In terms of item recall, diazepam and hyoscine produced impaired performance on unrelated words, but the impairment was reduced under conditions of either phonemic or semantic similarity. There were also some interesting differences between diazepam and hyoscine in terms of their effects upon the shape of the serial-position curve and upon the types of intrusion error. The results confirm that both diazepam and hyoscine impair acquisition processes but fail to distinguish the effects of the two drugs upon different categories of encoding operations.     

Is Language Required to Represent Others’ Mental States? Evidence From Beliefs and Other Representations

An important part of our Theory of Mind—the ability to reason about other people's unobservable mental states—is the ability to attribute false beliefs to others. We investigated whether processing these false beliefs, as well as similar but nonmental representations, is reliant on language. Participants watched videos in which a protagonist hides a gift and either takes a photo of it or writes a text about its location before a second person inadvertently moves the present to a different location, thereby rendering the belief and either the photo or text false. At the same time, participants performed either a concurrent verbal interference task (rehearsing strings of digits) or a visual interference task (remembering a visual pattern). Results showed that performance on false belief trials did not decline under verbal interference relative to visual interference. We interpret these findings as further support for the view that language does not form an essential part of the process of reasoning online (“in the moment”) about false beliefs.