Self-prioritization in working memory gating.

Working memory (WM) involves a dynamic interplay between temporary maintenance and updating of goal-relevant information. The balance between maintenance and updating is regulated by an input-gating mechanism that determines which information should enter WM (gate opening) and which should be kept out (gate closing). We investigated whether updating and gate opening/closing are differentially sensitive to the kind of information to be encoded and maintained in WM. Specifically, since the social salience of a stimulus is known to affect cognitive performance, we investigated if self-relevant information differentially impacts maintenance, updating, or gate opening/closing. Participants first learned to associate two neutral shapes with two social labels (i.e., "you" vs. "stranger"), respectively. Subsequently they performed the reference-back paradigm, a well-established WM task that disentangles WM updating, gate opening, and gate closing. Crucially, the shapes previously associated with the self or a stranger served as target stimuli in the reference-back task. We replicated the typical finding of a repetition benefit when consecutive trials require opening the gate to WM. In Study 1 (N = 45) this advantage disappeared when self-associated stimuli were recently gated into WM and immediately needed to be replaced by stranger-associated stimuli. However, this was not replicated in a larger sample (Study 2; N = 90), where a repetition benefit always occurred on consecutive gate-opening trials. Overall, our results do not provide evidence that the self-relevance of stimuli modulates component processes of WM. We discuss possible reasons for this null finding, including the importance of continuous reinstatement and task-relevance of the shape-label associations.

To vaccinate or not to vaccinate? The interplay between pro- and against- vaccination reasons.

BACKGROUND: By mid 2023, European countries reached 75% of vaccine coverage for COVID-19 and although vaccination rates are quite high, many people are still hesitant. A plethora of studies have investigated factors associated with COVID-19 vaccine hesitancy, however, insufficient attention has been paid to the reasons why people get vaccinated against COVID-19. Our work aims to investigate the role of reasons in the decision to get vaccinated against COVID-19 in a representative sample of 1,689 adult Italians (March-April 2021) balanced in terms of age, gender, educational level and area of residence. METHODS: Through an online questionnaire, we asked participants to freely report up to three reasons for and against COVID-19 vaccination, and the weight each had in the decision to get vaccinated. We first investigated the role of emotional competence and COVID-19 risk perception in the generation of both reasons using regression models. Next, we studied the role that the different reasons had in the vaccination decision, considering both the intention to vaccinate (using a beta regression model) and the decision made by the participants who already had the opportunity to get vaccinated (using a logistic regression model). Finally, two different classification tree analyses were carried out to characterize profiles with a low or high willingness to get vaccinated or with a low or high probability to accept/book the vaccine. RESULTS: High emotional competence positively influences the generation of both reasons (ORs > 1.5), whereas high risk perception increases the generation of positive reasons (ORs > 1.4) while decreasing reasons against vaccination (OR = 0.64). As pro-reasons increase, vaccination acceptance increases, while the opposite happens as against-reasons increase (all p < 0.001). One strong reason in favor of vaccines is enough to unbalance the decision toward acceptance of vaccination, even when reasons against it are also present (p < 0.001). Protection and absence of distrust are the reasons that mostly drive willingness to be vaccinated and acceptance of an offered vaccine. CONCLUSIONS: Knowing the reasons that drive people's decision about such an important choice can suggest new communication insights to reduce possible negative reactions toward vaccination and people's hesitancy. Results are discussed considering results of other national and international studies.

People's perspectives about COVID-19 vaccination certificate: Findings from a representative Italian sample.

In Italy, like in other countries, issues still exist regarding how to reach high vaccine coverage and several countries have considered policies to increase vaccine uptake. In the present study, we focused on people who have a favorable attitude towards vaccination. In March-April 2021, we asked a representative sample of Italian participants (N = 1,530) to assess to what extent they would support the adoption of a COVID-19 vaccination certificate, excluding unvaccinated people from participating in public and cultural events. Furthermore, as the vaccination coverage increases, severe forms of COVID-19 requiring hospitalization more likely involve unvaccinated individuals, who might be perceived as those who don't contribute to ending the pandemic and who constitute a significant health cost for society. We then asked participants to assess to what extent they would favor the idea of requiring people who refuse the vaccine to pay for their own medical expenses in case of hospitalization. We hypothesized that support for the adoption of the vaccination certificate would be predicted by the COVID-19 vaccination status (received, booked, high-, medium-, low-willingness to be vaccinated, or refused) and by the same factors that are known to affect the willingness to get vaccinated. These factors were also tested in a model aimed at investigating if a vaccinated person would favor a measure requiring the unvaccinated individuals to pay for medical expenses. Results confirmed that the support towards the vaccination certificate policy was strongly predicted by the vaccination status and by factors known to affect the willingness to get vaccinated. Interestingly (and surprisingly), a similar pattern was observed for the support of the policy about medical expenses. In conclusion, support for a COVID-19 vaccination certificate was high among the Italian population in the early phases of the vaccination rollout. The findings are discussed considering potential policies to tackle the pandemic.

When task sharing reduces interference: evidence for division-of-labour in Stroop-like tasks.

Performing a task with another person may either enhance or reduce the interference produced by task-irrelevant information. In three experiments, we employed the joint version of a Stroop-like task (i.e., the picture-word interference-PWI-task) to investigate some of the task features that seem to be critical in determining the effect of task-irrelevant information when the task is shared between two individuals. Participants were asked to perform a PWI task, which required to name a picture while ignoring a distractor word, first individually (in a baseline block of trials) and then co-acting with an alleged partner. Results showed that, compared to the baseline and to a condition in which participants continued to perform the PWI task individually, the belief of co-acting with another individual who was thought to be in charge of the distractor words suppressed the semantic interference effect when these words were in case alternation letters (e.g., "mOuSe"). Conversely, the semantic interference effect persisted when the co-actor was thought to be in charge of the same task as the participant, that is, the co-actor was thought to respond to the pictures. These results are accounted for by assuming that, when the participant knows that another person is in charge of the task-irrelevant information, a division-of-labour between participant and co-actor can be established. Such a division-of-labour may provide the participant with a strategy to oppose the semantic interference effect. Our findings, therefore, suggest that sharing a task with another person in charge of potentially interfering information can enable people to filter out this information from their own task representation.

Personality assimilation across species: enfacing an ape reduces own intelligence and increases emotion attribution to apes.

Seeing another person's face while that face and one's own face are stroked synchronously or controlling a virtual face by moving one's own induces the illusion that the other face has become a part of oneself-the enfacement effect. Here, we demonstrate that humans can enface even members of another species and that this enfacement promotes "feature migration" in terms of intelligence and emotional attribution from the representation of other to the representation of oneself, and vice versa. We presented participants with a virtual human face moving in or out of sync with their own face, and then morphed it into an ape face. Participants tended to perceive the ape face as their own in the sync condition, as indicated by body-ownership and inclusion-of-others-in-the-self ratings. More interestingly, synchrony also reduced performance in a fluid-intelligence task and increased the willingness to attribute emotions to apes. These observations, which fully replicated in another experiment, fit with the idea that self and other are represented in terms of feature codes, just like non-social events (as implied by the Theory of Event Coding), so that representational self-other overlap invites illusory conjunctions of features from one representation to the other.

Transcutaneous vagus nerve stimulation (tVNS) enhances recognition of emotions in faces but not bodies.

The polyvagal theory suggests that the vagus nerve is the key phylogenetic substrate enabling optimal social interactions, a crucial aspect of which is emotion recognition. A previous study showed that the vagus nerve plays a causal role in mediating people's ability to recognize emotions based on images of the eye region. The aim of this study is to verify whether the previously reported causal link between vagal activity and emotion recognition can be generalized to situations in which emotions must be inferred from images of whole faces and bodies. To this end, we employed transcutaneous vagus nerve stimulation (tVNS), a novel non-invasive brain stimulation technique that causes the vagus nerve to fire by the application of a mild electrical stimulation to the auricular branch of the vagus nerve, located in the anterior protuberance of the outer ear. In two separate sessions, participants received active or sham tVNS before and while performing two emotion recognition tasks, aimed at indexing their ability to recognize emotions from facial and bodily expressions. Active tVNS, compared to sham stimulation, enhanced emotion recognition for whole faces but not for bodies. Our results confirm and further extend recent observations supporting a causal relationship between vagus nerve activity and the ability to infer others' emotional state, but restrict this association to situations in which the emotional state is conveyed by the whole face and/or by salient facial cues, such as eyes.

Darwin revisited: The vagus nerve is a causal element in controlling recognition of other's emotions.

Charles Darwin proposed that via the vagus nerve, the tenth cranial nerve, emotional facial expressions are evolved, adaptive and serve a crucial communicative function. In line with this idea, the later-developed polyvagal theory assumes that the vagus nerve is the key phylogenetic substrate that regulates emotional and social behavior. The polyvagal theory assumes that optimal social interaction, which includes the recognition of emotion in faces, is modulated by the vagus nerve. So far, in humans, it has not yet been demonstrated that the vagus plays a causal role in emotion recognition. To investigate this we employed transcutaneous vagus nerve stimulation (tVNS), a novel non-invasive brain stimulation technique that modulates brain activity via bottom-up mechanisms. A sham/placebo-controlled, randomized cross-over within-subjects design was used to infer a causal relation between the stimulated vagus nerve and the related ability to recognize emotions as indexed by the Reading the Mind in the Eyes Test in 38 healthy young volunteers. Active tVNS, compared to sham stimulation, enhanced emotion recognition for easy items, suggesting that it promoted the ability to decode salient social cues. Our results confirm that the vagus nerve is causally involved in emotion recognition, supporting Darwin's argumentation.

l-Tyrosine administration modulates the effect of transcranial direct current stimulation on working memory in healthy humans.

BACKGROUND: Transcranial direct current stimulation (tDCS) is an increasingly popular method of modulating cognitive functions in humans. However, some doubt its efficacy as findings are inconsistent or remain unreplicated. It is speculated dopamine (DA) might play an important role in this inconsistency, by determining the direction and strength of the cognitive-behavioral effects of tDCS. However, so far evidence for this hypothesis has been correlational in nature, precluding definitive conclusions. OBJECTIVE: The present proof-of-principle study aimed at investigating a potentially causal role for DA in the effect of tDCS on cognition in healthy humans. METHODS: In Experiment 1 we aimed to replicate previous findings showing administration of DA's precursor l-Tyrosine (Tyr), presumably by inducing a modest increase in DA level, can enhance working memory (WM) performance as assessed with a verbal N-back task. In Experiment 2 we investigated the effect of Tyr administration on bilateral tDCS over dorsolateral prefrontal cortex (DLPFC) and WM. RESULTS: Experiment 1 showed Tyr administration enhances performance in a verbal N-back task. Experiment 2 showed Tyr modulates the effect of bilateral tDCS over DLPFC on WM. Specifically, tDCS had opposite effects on performance depending on current direction through the brain and Tyr administration. CONCLUSIONS: The present study provides two major findings. First, we replicate Tyr's beneficial effect on verbal WM. Second, our results indicate a causal role for DA in the effect of tDCS on cognition. For this reason, we encourage future studies to consider the modulating effect of DA, as a step towards more consistent and replicable results regarding the efficacy of tDCS.

The effect of gamma-enhancing binaural beats on the control of feature bindings.

Binaural beats represent the auditory experience of an oscillating sound that occurs when two sounds with neighboring frequencies are presented to one's left and right ear separately. Binaural beats have been shown to impact information processing via their putative role in increasing neural synchronization. Recent studies of feature-repetition effects demonstrated interactions between perceptual features and action-related features: repeating only some, but not all features of a perception-action episode hinders performance. These partial-repetition (or binding) costs point to the existence of temporary episodic bindings (event files) that are automatically retrieved by repeating at least one of their features. Given that neural synchronization in the gamma band has been associated with visual feature bindings, we investigated whether the impact of binaural beats extends to the top-down control of feature bindings. Healthy adults listened to gamma-frequency (40 Hz) binaural beats or to a constant tone of 340 Hz (control condition) for ten minutes before and during a feature-repetition task. While the size of visuomotor binding costs (indicating the binding of visual and action features) was unaffected by the binaural beats, the size of visual feature binding costs (which refer to the binding between the two visual features) was considerably smaller during gamma-frequency binaural beats exposure than during the control condition. Our results suggest that binaural beats enhance selectivity in updating episodic memory traces and further strengthen the hypothesis that neural activity in the gamma band is critically associated with the control of feature binding.

High body mass index is associated with impaired cognitive control.

The prevalence of weight problems is increasing worldwide. There is growing evidence that high body mass index (BMI) is associated with frontal lobe dysfunction and cognitive deficits concerning mental flexibility and inhibitory control efficiency. The present study aims at replicating and extending these observations. We compared cognitive control performance of normal weight (BMI < 25) and overweight (BMI ≥ 25) university students on a task tapping either inhibitory control (Experiment 1) or interference control (Experiment 2). Experiment 1 replicated previous findings that found less efficient inhibitory control in overweight individuals. Experiment 2 complemented these findings by showing that cognitive control impairments associated with high BMI also extend to the ability to resolve stimulus-induced response conflict and to engage in conflict-driven control adaptation. The present results are consistent with and extend previous literature showing that high BMI in young, otherwise healthy individuals is associated with less efficient cognitive control functioning.

More attentional focusing through binaural beats: evidence from the global-local task.

A recent study showed that binaural beats have an impact on the efficiency of allocating attention over time. We were interested to see whether this impact affects attentional focusing or, even further, the top-down control over irrelevant information. Healthy adults listened to gamma-frequency (40 Hz) binaural beats, which are assumed to increase attentional concentration, or a constant tone of 340 Hz (control condition) for 3 min before and during a global-local task. While the size of the congruency effect (indicating the failure to suppress task-irrelevant information) was unaffected by the binaural beats, the global-precedence effect (reflecting attentional focusing) was considerably smaller after gamma-frequency binaural beats than after the control condition. Our findings suggest that high-frequency binaural beats bias the individual attentional processing style towards a reduced spotlight of attention.

High-Frequency Binaural Beats Increase Cognitive Flexibility: Evidence from Dual-Task Crosstalk.

Increasing evidence suggests that cognitive-control processes can be configured to optimize either persistence of information processing (by amplifying competition between decision-making alternatives and top-down biasing of this competition) or flexibility (by dampening competition and biasing). We investigated whether high-frequency binaural beats, an auditory illusion suspected to act as a cognitive enhancer, have an impact on cognitive-control configuration. We hypothesized that binaural beats in the gamma range bias the cognitive-control style toward flexibility, which in turn should increase the crosstalk between tasks in a dual-task paradigm. We replicated earlier findings that the reaction time in the first-performed task is sensitive to the compatibility between the responses in the first and the second task-an indication of crosstalk. As predicted, exposing participants to binaural beats in the gamma range increased this effect as compared to a control condition in which participants were exposed to a continuous tone of 340 Hz. These findings provide converging evidence that the cognitive-control style can be systematically biased by inducing particular internal states; that high-frequency binaural beats bias the control style toward more flexibility; and that different styles are implemented by changing the strength of local competition and top-down bias.

Effects of Concomitant Stimulation of the GABAergic and Norepinephrine System on Inhibitory Control - A Study Using Transcutaneous Vagus Nerve Stimulation.

BACKGROUND: Inhibitory control processes are a central executive function. Several lines of evidence suggest that the GABAergic and the norepinephrine (NE) system modulate inhibitory control processes. Yet, the effects of conjoint increases in the GABAergic and NE system activity on inhibitory control have not been examined. OBJECTIVE/HYPOTHESIS: We examine the conjoint effects of the GABA and NE system for inhibitory control. METHODS: We used transcutaneous vagus nerve stimulation (tVNS), which has been shown to modulate both the GABAergic and NE system. We examine the effects of tVNS in two experimental paradigms examining different aspect of inhibitory control; i.e. a backward inhibition paradigm and a response inhibition paradigm modulating working memory load. RESULTS: There were no effects of tVNS on backward inhibition processes, but on response inhibition processes. Yet, these only emerged when working memory processes were needed to control response inhibition. Compared to a sham stimulation, tVNS induced better response inhibition performance (i.e. fewer false alarms). CONCLUSIONS: A concomitant modulation of the GABAergic and NE system, as induced by tVNS, affects inhibitory control processes, but only when working memory processes play an important role for inhibitory control. Even though both the GABAergic and the NE system are modulated by tVNS, the results suggest that the modulation of the NE system is most important for the emerging effects.

Effects of l-Tyrosine on working memory and inhibitory control are determined by DRD2 genotypes: A randomized controlled trial.

l-Tyrosine (TYR), the precursor of dopamine (DA), has been shown to enhance facets of cognitive control in situations with high cognitive demands. However some previous outcomes were mixed: some studies reported significant improvements, while other did not. Given that TYR increases DA level in the brain, we investigated, in a double-blind, randomized, placebo-controlled design, whether the C957T genotypes of a functional synonymous polymorphism in the human dopamine D2 receptor (DRD2) gene (rs6277) contribute to individual differences in the reactivity to TYR administration and whether this factor predicts the magnitude of TYR-induced performance differences on inhibiting behavioral responses in a stop-signal task and working memory (WM) updating in a N-back task. Our findings show that T/T homozygotes (i.e., individuals potentially associated with lower striatal DA level) showed larger beneficial effects of TYR supplementation than C/C homozygotes (i.e., individuals potentially associated with higher striatal DA level), suggesting that genetically determined differences in DA function may explain inter-individual differences in response to TYR supplementation. These findings reinforce the idea that genetic predisposition modulates the effect of TYR in its role as cognitive enhancer.

The stimulated social brain: effects of transcranial direct current stimulation on social cognition.

Transcranial direct current stimulation (tDCS) is an increasingly popular noninvasive neuromodulatory tool in the fields of cognitive and clinical neuroscience and psychiatry. It is an inexpensive, painless, and safe brain-stimulation technique that has proven to be effective in modulating cognitive and sensory-perceptual functioning in healthy individuals and clinical populations. Importantly, recent findings have shown that tDCS may also be an effective and promising tool for probing the neural mechanisms of social cognition. In this review, we present the state-of-the-art of the field of tDCS research in social cognition. By doing so, we aim to gather knowledge of the potential of tDCS to modulate social functioning and social decision making in healthy humans, and to inspire future research investigations.