Expectancy-based strategic processes are influenced by spatial working memory load and individual differences in working memory capacity

The present research examined whether imposing a high (or low) working memory (WM) load in different types of nonverbal WM task could affect the implementation of expectancy-based strategic processes in a sequential verbal Stroop task. Participants had to identify a colored target (a red vs. green patch) that was preceded by a prime word (RED or GREEN), which was incongruent with the target color on 80% of the trials, and congruent on 20% of trials. Previous findings have shown that participants can strategically use this information to predict the upcoming target color, and avoid the standard Stroop interference effect. The Stroop task was combined with different types of nonverbal WM task. In Experiment 1, participants had to retain sets of four arrows that pointed either in the same direction (low load) or in different directions (high load). In Experiment 2, they had to remember the spatial locations of four dots which either formed a straight line (low load) or were randomly scattered in a square grid (high load).In addition, participants in the two experiments performed a change localization task to obtain a measure of their WM capacity (WMC). The results in both experiments showed a reliable interaction between prime-target congruency and WM load. When participants performed the Stroop task under high WM load, they were unable to efficiently ignore the incongruence of the prime, as they consistently showed a standard Stroop effect, regardless of their WMC. Under a low WM load, however, a strategy-dependent (reversed Stroop) effect was observed. This ability to ignore the incongruence of the prime was modulated by WMC, such that the reversed Stroop effect was mainly found in higher WMC participants. The findings that expectancy-based strategies on a verbal Stroop task are modulated by load on different types of spatial WM tasks point at a domain-general effect of WM on strategic processing. The present results also suggest that the impact of loading WM on expectancy-based strategies can be modulated by individual differences in WMC

Fifteen species in one: deciphering the Brachionus plicatilis species complex (Rotifera, Monogononta) through DNA taxonomy

Understanding patterns and processes in biological diversity is a critical task given current and rapid environmental change. Such knowledge is even more essential when the taxa under consideration are important ecological and evolutionary models. One of these cases is the monogonont rotifer cryptic species complex Brachionus plicatilis, which is by far the most extensively studied group of rotifers, is widely used in aquaculture, and is known to host a large amount of unresolved diversity. Here we collate a dataset of previously available and newly generated sequences of COI and ITS1 for 1273 isolates of the B. plicatilis complex and apply three approaches in DNA taxonomy (i.e. ABGD, PTP, and GMYC) to identify and provide support for the existence of 15 species within the complex. We used these results to explore phylogenetic signal in morphometric and ecological traits, and to understand correlation among the traits using phylogenetic comparative models. Our results support niche conservatism for some traits (e.g. body length) and phylogenetic plasticity for others (e.g. genome size)

Brain Potentials Highlight Stronger Implicit Food Memory for Taste than Health and Context Associations

Increasingly consumption of healthy foods is advised to improve population health. Reasons people give for choosing one food over another suggest that non-sensory features like health aspects are appreciated as of lower importance than taste. However, many food choices are made in the absence of the actual perception of a food's sensory properties, and therefore highly rely on previous experiences of similar consumptions stored in memory. In this study we assessed the differential strength of food associations implicitly stored in memory, using an associative priming paradigm. Participants (N = 30) were exposed to a forced-choice picture-categorization task, in which the food or non-food target images were primed with either non-sensory or sensory related words. We observed a smaller N400 amplitude at the parietal electrodes when categorizing food as compared to non-food images. While this effect was enhanced by the presentation of a food-related word prime during food trials, the primes had no effect in the non-food trials. More specifically, we found that sensory associations are stronger implicitly represented in memory as compared to non-sensory associations. Thus, this study highlights the neuronal mechanisms underlying previous observations that sensory associations are important features of food memory, and therefore a primary motive in food choice.</p

Perception without awareness: further evidence from a Stroop priming task.

In the present research, we examined the influence of prime-target stimulus onset asynchrony (SOA) on Stroop-priming effects from masked words. Participants indicated the color of a central target, which was preceded by a 33-msec prime word followed either immediately or after a variable delay by a pattern mask. The prime word was incongruent or congruent with the target color on 75% and 25% of the trials, respectively. The words followed by an immediate mask produced reliable Stroop interference at SOAs of 300 and 400 msec but not at SOAs of 500 and 700 msec. The words followed by a delayed mask produced a reversed (i.e., facilitatory) Stroop effect, which reached significance at an SOA of 400 msec or longer, but never at the shorter 300-msec SOA. Such an differential time course of both types of Stroop priming effects provides further evidence for the existence of qualitative differences between conscious and nonconscious perceptual processes

Repetition priming effects from attended vs. ignored single words in a semantic categorization task.

The present research examines priming effects from a centrally presented single-prime word to which participants were instructed to either attend or ignore. The prime word was followed by a single central target word to which participants made a semantic categorization (animate vs. inanimate) task. The main variables manipulated across experiments were attentional instructions (attend vs. ignore the prime word), presentation duration of the prime word (20, 50, 80 or 100 ms), prime-target stimulus onset asynchrony (SOA; 300 vs. 800 ms), and temporal presentation of instructions (before vs. after the prime word). The results showed (a) a consistent interaction between attentional instructions and repetition priming and (b) a qualitatively different ignored priming pattern as a function of prime duration: reduced positive priming (relative to the attend instruction) for prime exposures of 80 and 100 ms, and reliable negative priming for the shorter prime exposures of 20 and 50 ms. In addition (c), the differential priming pattern for attend and ignore trials was observed at a prime-target SOA of 800 ms (but not at a shorter 300-ms SOA) and only when instructions were presented before the prime word. Methodological and theoretical implications of the present findings for the extant negative priming literature are discussed

The International Journal of Biochemistry & Cell Biology

This work presents the design and synthesis of a series of novel 2-benzylquinuclidine derivatives, comprising 12 methiodide and 11 hydrochloride salts, and their structural and pharmacological characterization at the human (h) alpha 7 and alpha 4 beta 2 nicotinic receptors (nAChRs). The antagonistic potency of these compounds was tested by Ca2+ influx assays on cells expressing the h alpha 7 or h alpha 4 beta 2 nAChR subtype. To determine the inhibitory mechanisms, additional radioligand binding experiments were performed. The results indicate that the methiodides present the highest affinities for the flea nAChR agonist sites, while the same compounds bind preferably to the h alpha 4 beta 2 nAChR ion channel domain. These results indicate that the methiodides are competitive antagonists of the h alpha 7 nAChR but noncompetitive antagonists of the h alpha 4 beta 2 subtype. Docking and molecular dynamics simulations showed that the methiodide derivative 8d binds to the h alpha 7 orthosteric binding sites by forming stable cation-pi interactions between the quaternized quinulinuim moiety and the aromatic box in the receptor, whereas compounds 7j and 8j block the h alpha 4 beta 2 AChR ion channel by interacting with a luminal domain formed between the serine (position 6') and valine (position 13') rings that overlaps the imipramine binding site. (C) 2013 Elsevier Ltd. All rights reserve