Editing Serial-position effect (section)

===Ratio rule===

Overall, an important [[Empirical research|empirical]] observation regarding the recency effect is that it is not the absolute duration of retention intervals (RI, the time between end of study and test period) or of inter-presentation intervals (IPI, the time between different study items) that matters. Rather, the amount of recency is determined by the [[Rational choice theory|ratio]] of RI to IPI (the ratio rule). As a result, as long as this ratio is fixed, recency will be observed regardless of the absolute values of intervals, so that recency can be observed at all time scales, a phenomenon known as''' time-scale invariance'''. This contradicts dual-store models, which assume that recency depends on the size of STS, and the rule governing the displacement of items in the STS.{{citation needed|date=October 2017}}

Potential explanations either then explain the recency effect as occurring through a single, same mechanism, or re-explain it through a different type of model that postulates two different mechanisms for immediate and long-term recency effects. One such explanation is provided by Davelaar et al. (2005),<ref>{{cite journal | last1 = Davelaar | first1 = E. K. | last2 = Goshen-Gottstein | first2 = Y. | last3 = Ashkenazi | first3 = A. | last4 = Haarmann | first4 = H. J. | last5 = Usher | first5 = M. | year = 2005 | title = The demise of short-term memory revisited: Empirical and computational investigations of recency effects | journal = Psychological Review | volume = 112 | issue = 1| pages = 3–42 | doi=10.1037/0033-295x.112.1.3 | pmid=15631586| s2cid = 16327806 }}</ref> who argue that there are [[Dissociation (psychology)|dissociations]] between immediate and long-term recency phenomena that cannot be explained by a single-component memory model, and who argues for the existence of a STS that explains immediate recency, and a second mechanism based on contextual drift that explains long-term recency. The recency effect as well as the '''ratio''' changes in [[Alzheimer's disease]] and therefore can be used as an indicator of this disease condition from the earliest stages of neurodegeneration <ref>{{cite journal | vauthors = Kovács KA | title = Relevance of a Novel Circuit-Level Model of Episodic Memories to Alzheimer's Disease | journal = International Journal of Molecular Sciences | volume = 23 | issue = 1 | pages = 462 | date = December 2021 | doi = 10.3390/ijms23010462 | pmid = 35008886 | pmc = 8745479 | doi-access = free }}</ref>