Chunking and redintegration in verbal short-term memory
Memory for verbal material improves when words form familiar chunks. But how does theimprovement due to chunking come about? Two possible explanations are that the inputmight be actively recoded into chunks, each of which takes up less memory capacity thanitems not forming part of a chunk (a form of data compression), or that chunking is basedon redintegration. If chunking is achieved by redintegration, representations of chunks existonly in long-term memory and help to reconstructing degraded traces in short-termmemory. In six experiments using two-alternative forced choice recognition and immediateserial recall, we find that when chunks are small (two words) they display a patternsuggestive of redintegration, while larger chunks (three words), show a pattern consistentwith data compression. This is concurs with previous data showing that there is a costinvolved in recoding material into chunks in short-term memory. With smaller chunks thiscost seems to outweigh the benefits of recoding words into chunks. The main features ofthe serial recall data can be captured by a simple extension to the Primacy model of Pageand Norris (1998).