Multitrial free recall as a function of constant versus varied input orders and list length

BDNF Val66Met polymorphism is associated with consolidation of episodic memory during sleep

The brain-derived neurotrophic factor (BDNF) is an essential regulator of synaptic plasticity, a candidate neurobiological mechanism underlying learning and memory. A functional polymorphism in the BDNF gene, Val66Met (rs6265), has been linked to memory and cognition in healthy individuals and clinical populations. Sleep contributes to memory consolidation, yet information about the possible role of BDNF in this process is scarce. To address this question, we investigated the relationship between the BDNF Val66Met genotype and consolidation of episodic declarative and procedural (motor) non-declarative memories in healthy adults. The carriers of Met66 allele, as compared with Val66 homozygotes, showed stronger forgetting overnight (24hours after encoding), but not over shorter time (immediately or 20minutes after word list presentation). There was no effect of Val66Met genotype on motor learning. These data suggest that BDNF plays a role in neuroplasticity underlying episodic memory consolidation during sleep.

A comparative analysis of serial and free recall

Multitrial free and serial recall tasks differ both in recall instruction and in presentation order across trials. Waugh (1961) compared these paradigms with an intermediate condition: free recall with constant presentation order. She concluded that differences between free and serial recall were due only to recall instructions, and not to presentation order. The present study reevaluated the relation between free and serial recall, using Waugh's three conditions. By examining recall transitions and the organization of information retained across trials, we conclude that presentation order is an important factor, causing participants to exhibit the same temporal associations in serial recall and in free recall with constant presentation order.

Evidence for two processes underlying the serial position curve of single- and multi-trial free recall in a heterogeneous group of psychiatric patients: a confirmatory factor analytic study

The U-shaped serial position curve (SPC) of single-trial free recall is a well-established empirical fact, and there is ample evidence that it is the result of two different memory functions. However, it is insufficiently clear whether the same holds true for the SPC of multi-trial free recall. Free recall test measurements of two large heterogeneous groups of psychiatric patients were subjected to factor extraction using Principal Components Analysis and oblique rotation in two studies. The results of these two experiments show that the SPCs of single- and multi-trial free recall arise from the same two functions i.e. one function underlies the recency part, the other the primacy and middle (prerecency) part. Possible theoretical interpretations are discussed.

Effects of alcohol and white noise on recall of relevant and irrelevant task components

This study examined the effects of arousal, induced by alcohol and white noise, on the free recall of intentionally learned words and incidentally learned word-locations, in the presence or absence of word-order cues. The Activation-Deactivation Adjective Check List, a self-report measure of arousal showed that noise affected the tension dimension of arousal, whereas the moderate alcohol dose primarily affected the energy dimension of arousal. That the low dose exerted an arousing effect was evidenced by an increase in tension but only when combined with noise. When word-order was randomized over trials, noise improved word-recall and counteracted the deleterious effect of the moderate alcohol dose. When order remained fixed, however, the moderate dose impaired recall, and at that dose recall was worse under noise. Location-recall was impaired by the moderate dose, and it was superior when word-order remained fixed. It was concluded that recall was influenced by arousal mechanisms and that perceived task demand and consequent effort were possible factors contributing to the obtained effects.