Monday, February 29, 2016

Semantic and phonological contributions to short-term repetition and long-term cued sentence recall.

Meltzer, J.A., Rose, N.S., Deschamps, T., Leigh, R.C., Panamsky, L., Silberberg, A., Madani, N., & Links, K.S. (2016). Semantic and phonological contributions to short-term repetition and long-term cued sentence recall. Memory & Cognition, 44, 307-329.

Short-term memory(STM) involves the recall of information briefly held in mind. It is generally agreed that there is domain-specificity within STM such that recall of phonological information is impaired when a person is engaged in another phonological but not visuospatial task, and vice versa. It is equally well-accepted that phonological retention and recall is supported by activated semantic knowledge held in long-term memory (LTM). For example, better recall is observed for lists of known vs. unknown words, or sentences vs. strings of words reflecting the better retention of phonological strings with known semantic associations.

Another long-standing tenet of factors influencing encoding in LTM is the ‘level of processing’ of information (Craik & Lockhart, 1972). According to this view, better encoding (and recall) is achieved with deep vs. shallow processing of material presented. An example of shallow processing is making a superficial judgment about information such as the font a word is written or the phonological rhyme whereas deep processing involves semantic processing.

The authors of the present study argued that shifting participants towards greater reliance on semantic processing would enhance long-term recall of presented information even if the manipulation disrupted short-term recall. Participants completed a sentence repetition task as follows: A sentence was presented and during an initial short delay, the participant completed a phonological task or a non-phonological, finger tapping task. The phonological task was expected to disrupt phonological encoding and shift reliance towards semantic processing, whereas no such shift was expected for the finger tapping task. After 100 sentences were completed, participants completed a cued LTM task in which they were given pairs of two words that cued one of the sentences previously presented and asked to recall as much of the sentence as they could.

Not surprisingly, sentence recall from STM was lower when a phonological compared to nonphonological task was completed during a brief delay. Of greater interest was that the opposite pattern was observed for the LTM cued recall task: Relative to what they had remembered in the STM task, participants more accurately recalled sentences during which they had completed a phonological vs. nonphonological task at encoding. Further, sentences were either abstract or concrete with the idea that the abstract sentences would benefit more from the greater semantic processing achieved in the phonological disruption task. Indeed, the benefit to LTM recall after completing a phonological vs. nonphonological task at encoding was found to be greater for abstract than concrete sentences but only when the phonological task was demanding (i.e., counting backwards by 3 vs. repeating ‘babataka’).

These findings were taken as evidence that engaging semantic mechanisms at encoding to achieve a deeper level of processing promotes long-term retention. It would follow from this that rote immediate repetition is a poor strategy for promoting long-term learning as compared to strategies that engage learners with meaning.

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