The Relationship Between Visual Working Memory and Consciousness

Questo lavoro di tesi presenta una serie di evidenze meta-analitiche e sperimentali riguardo la relazione tra consapevolezza e memoria di lavoro visiva (VWM). La memoria di lavoro è sempre stata considerata direttamente legata all’esperienza consapevole. La ricerca recente tuttavia suggerisce che anche stimoli non percepiti consapevolmente possano essere mantenuti ed utilizzati in un compito di VWM. Ho condotto un lavoro meta-analitico su questi risultati dove emerge complessivamente un indice di grandezza dell’effetto di media grandezza, ma allo stesso tempo una notevole variabilità tra gli studi legata probabilmente alla tipologia di paradigma sperimentale. Successivamente, ho condotto 3 esperimenti utilizzando una tecnica di backward masking combinata ad un change-detection task (CDT). Negli esperimenti 1 e 3 ho inoltre analizzato la contralateral delay activity (CDA) come indice elettroencefalografico di VWM e la P3b come indice di consapevolezza visiva. La prestazione di memoria di lavoro visiva per stimoli non consapevoli non era sopra il livello del caso. Analizzando solo le prove corrette, la CDA differiva da zero per le prove non consapevoli mentre non differiva nel confronto tra prove consapevoli e non consapevoli. La P3b invece differiva tra la condizione consapevole e quella non consapevole. Negli esperimenti 2 e 3 ho ridotto la difficoltà del paradigma sperimentale e migliorato la metodologia di psicofisica. L’esperimento 2 aveva l’obiettivo di testare il ruolo della soglia percettiva (50%, 65% e 80%) nella prestazione nel compito di VWM. I risultati suggeriscono che all’aumentare della soglia percettiva aumentavano anche le performance nel CDT quando la soglia era maggiore del 50%. Riguardo l’esperimento 3 sono emersi gli stessi risultati ERP dell’esperimento 1. In termini comportamentali, utilizzando il paradigma implementato nell’esperimento 2, la prestazione era sopra il livello del caso per stimoli non consapevoli. In conclusione emerge critico il ruolo della difficoltà del compito (CDT) e l’approccio psicofisico utilizzato. In termini neurali, la CDA sembra essere legata alla presenza dell’informazione a prescindere dall’esperienza riportata mentre la P3b è modulata dall’esperienza soggettiva riportata.The thesis presents meta-analytical, behavioral, and neural findings about the relationship between visual working memory (VMW) and consciousness. Working memory has always been considered as strictly related to the conscious experience. A series of recent findings and theoretical proposals questioned this relationship, suggesting the possibility that unconscious stimuli are processed in visual working memory. I conducted a meta-analysis of these findings suggesting the presence of a medium effect with a significant amount of heterogeneity mainly explained by the experimental setup. Then, in a series of three experiments using backward masking and psychophysical adaptive procedures, I assessed the short-term maintenance of Gabor patches within a change-detection task (CDT). Furthermore, in Experiment 1 and Experiment 3, I analyzed the Contralateral Delay Activity (CDA) as an event-related potential correlate of visual working memory and the P3b as an index of visual consciousness. In Experiment 1 the VWM performance was not higher than the chance level. Considering correct trials, the CDA was different from zero for unconscious trials. There was no difference between unconscious and conscious trials. On the other side, the P3b significantly differed between conscious and unconscious trials. For experiments 2 and 3 I modified the experimental setup, decreasing the CDT difficulty and improving the psychophysical approach. Experiment 2 tested the role of the subjective psychophysical threshold for the VWM unconscious performance. Results suggest that the increase of the subjective threshold (50%, 65%, and 80%) increased unconscious VWM performance when the threshold is higher than 50%. In Experiment 3 I found the same ERP pattern as in Experiment 1. On the other side, with the experimental setup from Experiment 2, the behavioral performance was above the chance level. Overall, when studying unconscious VWM, it is crucial to carefully consider the task accuracy and the psychophysical setup. In terms of neural data, the CDA seems to track the presence of the information without being affected by the reported experience, while the P3b is modulated by the subjective experience

Understanding meta-analysis through data simulation with applications to power analysis

Meta-analysis is a powerful tool to combine evidence from existing literature. Despite several introductory and advanced materials about organizing, conducting, and reporting a meta-analysis, to our knowledge, there are no introductive materials about simulating the most common meta-analysis models. Data simulation is essential for developing and validating new statistical models and procedures. Furthermore, data simulation is a powerful educational tool for understanding a statistical method. In this tutorial, we show how to simulate fixed-effects, random-effects, and meta-regression models and illustrate how to estimate statistical power. In the supplementary materials, we extended these simulations also for multilevel and multivariate models

Deficits of visual working memory representations of emotional facial expressions in patients with congenital facial palsy

In light of sensorimotor simulation theories, the aim of this project is to investigate the impact of a congenital facial palsy on visual working memory representations for emotional faces

Understanding meta-analysis through data simulation with applications to power analysis

Meta-analysis is a very important tool to combine evidence from multiple studies. When comes to understanding a new statistical method, data simulation is a powerful educational tool. In this tutorial, we present how to simulate the most common meta-analysis models and meta-regressions

sj-pdf-1-amp-10.1177_25152459231209330 – Supplemental material for Understanding Meta-Analysis Through Data Simulation With Applications to Power Analysis

Supplemental material, sj-pdf-1-amp-10.1177_25152459231209330 for Understanding Meta-Analysis Through Data Simulation With Applications to Power Analysis by Filippo Gambarota and Gianmarco Altoè in Advances in Methods and Practices in Psychological Science</p