Analyses of errors from a sequential auditory recall experiment indicated that perceptual factors influence the shape of the serial position curve of recall errors. The signal to noise ratio and presentation rate of the stimuli, as well as presentation rate during a prior training session, affected item and order errors. For experiments in which Ss simply monitored the auditory sequences for a preassigned critical item, and in which items were recalled in addition to monitoring, analyses of montoring RTs provided evidence (...) that the requirement to recall induces perceptual difficulties. (shrink)