Stimulus modality and short-term memory in rats

Two experimental paradigms are presented aimed at determining the retention of auditory and visual information over brief delay intervals. First, a conditional delayed matching-to-sample procedure was used in which rats were required to symbolically match the modality of the sample stimulus with one of two comparison stimuli. In the second experiment, subjects were trained and tested using a Konorski-type procedure. Despite the conceptual and procedural differences between the two procedures, subjects in both experiments showed steeper forgetting functions for visual events than for auditory events, while performance levels at 0-sec delay intervals were equivalent for both stimuli. These results, when taken together with related research conducted with pigeons, suggest that content of memory may have important influences on the short-term retention abilities of animal subjects.