Serial position effects in 2-alternative forced choice recognition: Functional equivalence across visual and auditory modalities

Two experiments examined Ward, Avons and Melling’s (2005) proposition that the serial position function is task, rather than modality, dependent. Specifically, they proposed that for backward testing the 2-alternative forced choice (2AFC) recognition paradigm is characterised by single-item recency irrespective of the modality of the stimulus presentation. In Experiment 1 the same nonwords sequences, presented both visually or auditorially, produced qualitatively equivalent serial position functions with 2AFC testing. Forward testing produced a flat serial position function, whilst backward testing produced two-item recency in the absence of primacy. In order to rule out the possibility that the serial position functions for visual stimuli were the product of sub-vocal rehearsal, Experiment 2 employed articulatory suppression during the presentation phase. Serial position function equivalence was again observed together with a modest impairment in overall recognition rates. Taken together, these data are consistent with the Ward et al. proposition and further support the existence of a visual memory that can facilitate storage of visual-verbal material e.g. Logie, Della Sella, Wynn, and Baddeley (2000). However, the observation of two-item recency contradicts the original Duplex account of single-item recency traditionally observed for backwards recognition testing of visual stimuli (Phillips and Christie, 1977)

Serial position functions for recognition of olfactory stimuli

Two experiments examined item recognition memory for sequentially presented odours. Following a sequence of six odours participants were immediately presented with a series of 2-alternative forced choice (2AFC) test odours. The test pairs were presented in either the same order as learning or the reverse order of learning. Method of testing was either blocked (Experiment 1) or mixed (Experiment 2). Both experiments demonstrated extended recency, with an absence of primacy, for the reverse testing procedure. In contrast, the forward testing procedure revealed a null effect of serial position. The finding of extended recency is inconsistent with the single-item recency predicted by the two-component duplex theory (Phillips and Christie, 1977). We offer an alternative account of the data in which recognition accuracy is better accommodated by the cumulative number of items presented between item learning and item test

Switching between chewing-gum and no-gum at learning and retrieval does not accentuate error production in free recall

Three experiments compared chewing gum to a no gum condition to examine further the finding (Anderson, Berry, Morse & Diotte, 2005) that switching flavour between learning and recall encourages error production independently of free recall. In order to encourage error production, participants in Experiment 1 were told to guess responses at recall, participants in Experiment 2 were required to recall categorised word lists and in Experiment 3 participants repeated the same learning-recall combination on four immediately successive occasions and were required to recall different categorised word lists on each. The experiments produced universally null effects. Consistent with previous research, for correct recall, there were no independent effects of chewing gum for learning or recall and nor was their evidence of context dependency. Error production was not biased towards the inconsistent learning-recall contexts even when participants switched successively between the learning-recall contexts. Finally, there was no evidence that extended temporal exposure to chewing gum was an important determinant of context-dependent memory effects

Qualitative differences in the immediate recognition memory for wine and visual matrices

Objectives: The present study examined short-term recognition for gustatory stimuli (wines) and investigated the proposition that serial position effects are qualitatively equivalent across stimulus types (Ward et al., 2005). Design: Two experiments examined serial position effects for a single yes/no recognition task with gustatory (Experiment 1) and visual stimuli (Experiment 2). Methods: Two experiments were conducted (n=24 in each) each comprising 18 trials. Participants were presented with sequences of three wines (Experiment 1) or three matrices (Experiment 2). Each item was presented for five seconds with a five-second ISI (incorporating a palette cleanse). Following the three items, participants received a single recognition probe. Results: Recognition for wine revealed strong primacy with an indication of recency. In contrast, recognition for non-verbal stimuli (abstract matrices) revealed strong recency and no primacy. Conclusions: The primacy advantage reported for wines is consistent with the first item bias reported for wine preference judgments (Mantonakis et al., 2009). Furthermore, the qualitatively different serial position functions for gustatory stimuli (compared to non-verbal visual stimuli) is consistent with a model in which short-term memory for gustatory stimuli operate differently to that of other stimulus types

The contrasting physiological and subjective effects of chewing gum on social stress

Uncertainty exists with respect to the extent to which chewing gum may attenuate stress-induced rises in cortisol secretion (Scholey et al., 2009; Smith, 2010; Johnson et al., 2011). The present study used the Trier Social Stress Task (TSST: Kirschbaum et al., 1993), a task known to elevate cortisol secretion (Kudielka et al., 2004), in order to examine the moderating physiological and subjective effects of chewing gum on social stress. Forty participants completed the TSST either with or without chewing gum. As expected, completion of the TSST elevated both cortisol and subjective stress levels, whilst impairing mood. Although gum moderated the perception of stress, cortisol concentrations were higher following the chewing of gum. The findings are consistent with Smith (2010) who argued that elevations in cortisol following the chewing of gum reflect heightened arousal. The findings suggest that chewing gum only benefits subjective measures of stress. The mechanism remains unclear; however, this may reflect increased cerebral blood flow, cognitive distraction, and/or effects secondary to task facilitation

Kinetics of substrate oxidation and hydrogen peroxide production by Mycoplasma mycoides subsp. mycoides Large Colony (LC) type and Mycoplasma mycoides subsp. capri

Mycoplasma mycoides subsp. mycoides Large Colony (LC) type is a pathogen of goats causing contagious agalactia and respiratory disease, found on all continents where small ruminants are kept. It shares close genetic characteristics with M. mycoides subsp. capri. Substrate oxidation by 22 strains of M. mycoides subsp. mycoides LC from nine countries was compared with that of eight strains of M. mycoides subsp. capri from five countries. There was considerable similarity in the substrates used, but substrate saturation coefficients (Ks) varied for different substrates. Substrate utilization patterns and Ks values did not (1) significantly differentiate the LC strains from each other, (2) show any correlation with geographical origin, or (3) distinguish the LC strains from the capri strains. These results support previous studies justifying the reclassification of these subspecies as a single species