Cognitive stability and flexibility are a continuous trade-off. To exert stable task focus, humans need deeper attractor states and higher neural gain to shield distractors. For cognitive...Show moreCognitive stability and flexibility are a continuous trade-off. To exert stable task focus, humans need deeper attractor states and higher neural gain to shield distractors. For cognitive flexibility, shallower attractor states and lower gain are beneficial to switch tasks quicker. Individuals with attention deficit hyperactivity disorder (ADHD) seem to have problems adjusting stability and flexibility. This study examined the influence of two contextual demands on a computational estimate of neural gain. First, we expected people to increase neural gain with a higher proportion of incongruent stimuli to facilitate focus on the task relevant stimulus dimension. Second, we hypothesised that participants decrease neural gain when presented a short versus long cue to stimulus interval (CSI) to allow faster switching. Generally, we expected individuals with higher levels of ADHD to have lower gain and more difficulties adjusting it. These hypotheses were tested separately with a cued task-switch paradigm online. First, the proportion of incongruent stimuli was manipulated (75% versus 25%). With a high proportion incongruency, participants lowered their incongruency cost and increased switch cost. However, they did not change gain. Second, the CSI length was varied (300ms versus 1000ms). With a short CSI, people lowered gain and made more errors on incongruent switch trials. We found partial support that individuals with self-reported ADHD have less optimal gain. We recommend that individuals work in environments matching their demands. If a task demands focus, one should not work in a flexibility demanding space. When focus and accuracy are required, sufficient time must be given.Show less
Rationale: Anecdotal evidence suggests that microdosing (i.e., taking small doses of) psychedelics can enhance focus and increase productivity and creativity. However, the current literature on the...Show moreRationale: Anecdotal evidence suggests that microdosing (i.e., taking small doses of) psychedelics can enhance focus and increase productivity and creativity. However, the current literature on the benefits of microdosing on cognition is generally based on self-report and lacks adequate controls, leading to experimental bias and placebo effects. Methods: This study adds to the limited literature on microdosing by examining the effects of microdosing in two-randomized, double-blind, placebo-controlled, longitudinal trials. Specifically, we examined the effects of microdosing psilocybin truffles on various aspects of cognition and working memory. In the first experiment, 69 participants completed all sessions, and in the second experiment, a sample of 67 participants was studied. Participants were divided into two groups, a placebo and an active microdosing group, and completed the following tasks: AX-CPT, Multi-Armed Bandit, Attentional Blink, Remember-Know, Reference-Back, N-back, Inclusion of Other in the Self scale (IOS), and Trust Game. Based on previous theoretical research, we expected that the active microdosing group would perform better on tasks linked with cognitive flexibility while showing lower performance on tasks requiring top-down inhibition and persistent focus. Results: Contrary to our hypothesis, the results showed that microdosing had no significant effect on any of the tasks tapping into cognitive control or working memory. We did find some initial significant results for the IOS, but, after multiple comparison correction, these results were found to be nonsignificant. Importantly, participants in our study were not breaking blind, as has been the case in previous microdosing studies. Moreover, no negative effects on the tasks were found after microdosing, suggesting good tolerability of psychedelic microdosing. Conclusion: Our results showed no benefit of microdosing psychedelics on cognition. Therefore, the reported benefits are more likely driven by placebo effects. However, microdosing did not impair cognition and can therefore be considered relatively safe in healthy subjects.Show less
The bilingual brain has the ability to control and switch between languages at any given moment. This alternation between two languages is known as code-switching (Bullock & Toribio, 2009),...Show moreThe bilingual brain has the ability to control and switch between languages at any given moment. This alternation between two languages is known as code-switching (Bullock & Toribio, 2009), which requires cognitive control mechanisms to inhibit the first language once the second language is encountered (Green & Wei, 2014). During the process of switching from one language to the other, costs have been observed, which are assumed to mirror the effort required to access the target language schema. With this background in mind, this study examined the influence of intra-sentential code-switch types on cognitive control costs on (N= 70) L1 Greek L2 English bilinguals. We used an executive function task, where participants were presented with code-switched and non-code-switched sentences that were followed by either a comprehension question or a Flanker trial. Comprehension findings showed that higher scores in Accuracy lead to greater cognitive effort, and thus, costs on monolingual conditions, and in the presence of a code-switch, the costs and levels of Accuracy were decreased. Results from the Flanker task demonstrated a significant link between code-switching type and direction: the performance on Alternational Conditions demanded greater levels of inhibition, and entailed larger costs compared to Insertional Conditions, that caused lower costs. However, the overall performance was better when on the direction of the switch occurred from the L2 to L1, in all levels. Lastly, it was observed that after a code-switch sentence, the performance on Flanker Congruency was faster and more accurate in incongruent than congruent trials. These results provide evidence of the processing demands that intra-sentential code-switch types generate in terms of domain-general cognitive control cost mechanisms.Show less
