Academic journal article Memory & Cognition

Acoustic Masking Disrupts Time-Dependent Mechanisms of Memory Encoding in Word-List Recall

Academic journal article Memory & Cognition

Acoustic Masking Disrupts Time-Dependent Mechanisms of Memory Encoding in Word-List Recall

Article excerpt

Published online: 7 November 2013

© Psychonomic Society, Inc. 2013

Abstract Recall of recently heard words is affected by the clarity of presentation: Even if all words are presented with sufficient clarity for successful recognition, those that are more difficult to hear are less likely to be recalled. Such a result demonstrates that memory processing depends on more than whether a word is simply "recognized" versus "not recognized." More surprising is that, when a single item in a list of spoken words is acoustically masked, prior words that were heard with full clarity are also less likely to be recalled. To account for such a phenomenon, we developed the linking-by-active-maintenance model (LAMM). This computational model of perception and encoding predicts that these effects will be time dependent. Here we challenged our model by investigating whether and how the impact of acoustic masking on memory depends on presentation rate. We found that a slower presentation rate causes a more disruptive impact of stimulus degradation on prior, clearly heard words than does a fast rate. These results are unexpected according to prior theories of effortful listening, but we demonstrated that they can be accounted for by LAMM.

Keywords Recall . Association . Word list . Simulation . Short-term store

(ProQuest: ... denotes formulae omitted.)

When a speech signal is degraded, requiring perceptual effort for successful word recognition, recall for the speech content suffers. This is so whether perceptual effort is engendered by acoustic masking of speech stimuli for listeners with normal hearing acuity (Farley, Neath, Allbritton, & Surprenant, 2007; Murphy, Craik, Li, & Schneider, 2000; Surprenant, 1999)or by a mild-to-moderate hearing loss (McCoy et al., 2005; Rabbitt, 1990). Of importance, this negative effect on recall occurs even when the level of acoustic masking or the degree of hearing loss still allows for successful, albeit effortful, word recognition. This is an intriguing and much replicated phenomenon, but one whose source is not yet fully understood.

In the above-cited studies, masking has been applied to entire word lists or to sets of paired associates, thus obscuring the mechanisms that might underlie this effect. In a closer examination of the effect, Piquado, Cousins, Wingfield, and Miller (2010) demonstrated that masking just a single word in a spoken word list reduces the probability of recall, not only for the masked word itself, but also for an unmasked word prior to it. These data are shown in Fig. 1, demonstrating that, relative to the same word positions in control lists, a significant reduction was observed in the probability of recall for both the masked word (M ) and the prior word (-1), but not for words that followed the masked word. Importantly, this effect of masking occurred even though the level of masking allowed for correct, albeit effortful, identification of the masked word.1

It was argued that the effect of a masked word on prior- word recall resulted from a disrupted output pattern during recall. That is, for lists in which all of the words are presented clearly, it is typically found that participants tend to make contiguous transitions during recall. Specifically, recall of any word in a list, n ,ismostlikelyfollowedbyrecallofthe next word in the presented sequence, n +1(Howard& Kahana, 1999;Kahana,1996). An analysis of the Piquado et al. data indicated that the occurrence of a masked word resulted in fewer such n + 1 transitions between early list items, suggesting that this may have underlain the diminished recall for these items.

In a general sense, these results appear consistent with a "resource" account of the negative effects of perceptual effort on recall. This is the postulate that perceptual identification of a stimulus and higher-order processing draw on the same pool of limited resources (Murphy et al., 2000; Rabbitt, 1968, 1990; Schneider & Pichora-Fuller, 2000;Surprenant,1999, 2007). …

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