Final answer:
The neighborhood size effect suggests that short-term memory recall is influenced by the ease of item retrieval within a semantic network and factors like interference, not just by a fixed number of items that can be held in memory.
Step-by-step explanation:
The neighborhood size effect casts doubts about memory span being a measure of short-term memory capacity because it suggests that short-term memory is influenced by factors other than sheer capacity. For example, the ease with which items can be retrieved within a network might impact recall.
This casts doubt on the traditional view that short-term memory capacity is a fixed number of items (7 plus or minus 2, according to Miller's classic view). Research such as Cowan's indicates that a more accurate estimate of working memory capacity is 4 plus or minus 1.
This suggests that elements like semantic network size, interference, and the nature of the material being remembered (such as whether it's heard or seen, or whether it's numbers or letters) all play a role in what can be remembered in the short term, rather than a simple quantitative 'slot' capacity.