The Isolation, Primacy, and Recency Effects Predicted by an Adaptive LTD/LTP Threshold in Postsynaptic Cells

Abstract

An item that stands out (is isolated) from its context is better remembered than an item consistent with the context. This isolation effect cannot be accounted for by increased attention, because it occurs when the isolated item is presented as the first item, or by impoverished memory of nonisolated items, because the isolated item is better remembered than a control list consisting of equally different items. The isolation effect is seldom experimentally or theoretically related to the primacy or the recency effects-that is, the improved performance on the first few and last items, respectively, on the serial position curve. The primacy effect cannot easily be accounted for by rehearsal in short-term memory because it occurs when rehearsal is eliminated. This article suggests that the primacy, the recency, and the isolation effects can be accounted for by experience-dependent synaptic plasticity in neural cells. Neurological empirical data suggest that the threshold that determines whether cells will show long-term potentiation (LTP) or long-term depression (LTD) varies as a function of recent postsynaptic activity and that synaptic plasticity is bounded. By implementing an adaptive LTP-LTD threshold in an artificial neural network, the various aspects of the isolation, the primacy, and the recency effects are accounted for, whereas none of these phenomena are accounted for if the threshold is constant. This theory suggests a possible link between the cognitive and the neurological levels.

Endowment Effect and Housing Decisions

“…To illustrate the dynamics between WTA/ WTP and market conditions, we first define WTA and WTP as the weighted average of historical and recently available information. The definition is based on the well-established primacy and recency effects in psychology and neuroscience studies (capitani et al 1992;cowan et al 2002;Innocenti et al 2013;Sikström 2006). Baucells et al (2011) showed that reference points are formed primarily based on the first and last prices of the time series.…”

Simulating the cross-linguistic pattern of Optional Infinitive errors in children’s declaratives and Wh- questions

“…This is an important development since sentence-internal omission errors of this kind are a characteristic feature of children's early multi-word speech, which is often described as 'telegraphic' because of the high frequency with which such errors occur (Brown, 1973 This issue will be addressed in the present study by running simulations of children's use of Wh-questions across the four languages using the same version of the model as that absence of rehearsal (e.g. Neath, 1993;Sikström, 2006). Moreover, primacy (and recency) effects have also been found in non-human species (monkeys and pigeons), where active elaboration processes are unlikely to play a major role (Wright, Santiago, Sands, Kendrick & Rook, 1985).…”

Reactivation in Working Memory: An Attractor Network Model of Free Recall

“…Sandberg et al [19] proposed and studied a neural network model of WM based on fast and volatile Hebbian learning demonstrating recency without addressing the phenomenon of primacy. Sikström [20] accounted for primacy, recency, and the isolation effect (enhanced learning of odd items) with a single mechanism related to a biologically plausible learning rule. This form of learning suggests an adaptive threshold for induction of LTP and LTD, where primacy is accounted for by an increased LTP following a low threshold in the beginning of the list.…”