Serial recall of spectro-temporal patterns under informational masking

Abstract

This study investigated the memory costs associated with informational masking (IM) and the memory benefits associated with its reduction. A serial recall task was used wherein the stimuli to be recalled were random sequences of six possible learned spectro-temporal patterns masked by other random sequences of spectro-temporal patterns. Sequence lengths of 1, 3, and 5 were tested. In all conditions, a target sequence and a masker sequence were assigned to mutually exclusive frequency bands. In the high-IM reference condition, the frequency separation of the two bands was chosen so as to be just discriminable and the onsets of corresponding target and masker patterns roughly overlapped in time. In the comparison conditions, IM was reduced systematically by increasing the frequency separation of the two bands and staggering the onsets of corresponding patterns. When IM was high, recall was poor and memory costs were large. As IM was reduced, recall improved, revealing memory benefits typically not discernable in standard detection, discrimination, or recognition-based studies of IM. Large individual differences were found and a number of observers were unable to perform the task at the pre-established criterion level even after training in unmasked conditions. The interaction between IM and memory will be discussed.This study investigated the memory costs associated with informational masking (IM) and the memory benefits associated with its reduction. A serial recall task was used wherein the stimuli to be recalled were random sequences of six possible learned spectro-temporal patterns masked by other random sequences of spectro-temporal patterns. Sequence lengths of 1, 3, and 5 were tested. In all conditions, a target sequence and a masker sequence were assigned to mutually exclusive frequency bands. In the high-IM reference condition, the frequency separation of the two bands was chosen so as to be just discriminable and the onsets of corresponding target and masker patterns roughly overlapped in time. In the comparison conditions, IM was reduced systematically by increasing the frequency separation of the two bands and staggering the onsets of corresponding patterns. When IM was high, recall was poor and memory costs were large. As IM was reduced, recall improved, revealing memory benefits typically not discernab...