Biomedical subjects

Eddy J Davelaar

Publications and source records attributed to Eddy J Davelaar.

4 recordsLinked to original sources

PubMed2006

Semantic similarity dissociates short- from long-term recency effects: testing a neurocomputational model of list memory.

The finding that recency effects can occur not only in immediate free recall (i.e., short-term recency) but also in the continuous-distractor task (ie., long-term recency) has led many theorists to reject the distinction between short- and long-term memory stores. Recently, we have argued that long-term recency effects do not undermine the concept of a short-term store, and we have presented a neurocomputational model that accounts for both short- and long-term recency and for a series of dissociations between these two effects. Here, we present a new dissociation between short- and long-term recency based on semantic similarity, which is predicted by our model. This dissociation is due to the mutual support between associated items in the short-term store, which takes place in immediate free recall and delayed free recall but not in continuous-distractor free recall.

Arousal↗

PubMed2005

The demise of short-term memory revisited: empirical and computational investigations of recency effects.

In the single-store model of memory, the enhanced recall for the last items in a free-recall task (i.e., the recency effect) is understood to reflect a general property of memory rather than a separate short-term store. This interpretation is supported by the finding of a long-term recency effect under conditions that eliminate the contribution from the short-term store. In this article, evidence is reviewed showing that recency effects in the short and long terms have different properties, and it is suggested that 2 memory components are needed to account for the recency effects: an episodic contextual system with changing context and an activation-based short-term memory buffer that drives the encoding of item-context associations. A neurocomputational model based on these 2 components is shown to account for previously observed dissociations and to make novel predictions, which are confirmed in a set of experiments.

Adult↗

PubMed2005

Age-related declines in context maintenance and semantic short-term memory.

This study reports age-related declines in context maintenance (Braver et al., 2001) and semantic short-term memory (STM) and evidencc for a relation between the two. A group of younger and older adults completed a context maintenance task (AX-CPT), a semantically oriented STM task (conceptual span), a phonologically oriented STM task (digit span), and a meaning integration task (semantic anomaly judgement). In the AX-CPT task, a target response is required to the probe letter "X" but only when it is preceded by the letter "A" (the context). Either three (short interference) or six distractor letters (long interference) were presented between the cue and the probe. Results indicated an age-related deficit in context maintenance. Age-related declines were also observed for conceptual span and semantic anomaly judgement but not for digit span. Context maintenance was correlated with conceptual span and semantic anomaly judgement but not with digit span. These correlations were largely mediated by age differences, which also explained variance that was unique to (and not shared among) context maintenance, conceptual span, and semantic anomaly judgement.

Adult↗

PubMedDate not supplied

Neuromodulation of decision and response selection.

We present a model for the attentional neuromodulation of decision and selection processes. The model assumes that phasic responses in the brain nucleus Locus Coeruleus modulate, via the transmission of norepinephrine, the synaptic efficiency of neural circuits, at specific (stimulus and task dependent) time intervals. The model is applied first, to a task of perceptual choice, simulating attentional fluctuations and accounting for a series of behavioral and neurophysiological data. Second, the flexibility of information processing, whereby the parameters of the local circuits are modified online, is illustrated in the application of the model to a task of selection from short-term memory.

Animals↗