What does the serial-position curve refer to?

The serial-position curve refers specifically to the phenomenon where individuals tend to remember the first and last items in a list more vividly than those in the middle. This effect is explained by two components of memory: the primacy effect, which suggests that items presented at the beginning of a list are more likely to be transferred into long-term memory, and the recency effect, which indicates that items presented at the end remain accessible in short-term memory.

Therefore, option B accurately describes this concept by highlighting that recall is enhanced for items located at both the beginning and the end of a list, illustrating how position within the list affects memory performance. Other options do not capture this dual aspect of the serial-position curve effectively; for instance, while presentation speed or decay of memory might influence recall, they do not specifically pertain to the enhanced recall observed at the extremes of a list. Similarly, improved memory for middle items contradicts the core findings of the serial-position effect.