Attentional Guidance from Multiple Working Memory Representations: Evidence from Eye Movements

Recent studies have shown that the representation of an item in visual working memory (VWM) can bias the deployment of attention to stimuli in the visual scene possessing the same features. When multiple item representations are simultaneously held in VWM, whether these representations, especially those held in a non-prioritized or accessory status, are able to bias attention, is still controversial. In the present study we adopted an eye tracking technique to shed light on this issue. In particular, we implemented a manipulation aimed at prioritizing one of the VWM representation to an active status, and tested whether attention could be guided by both the prioritized and the accessory representations when they reappeared as distractors in a visual search task. Notably, in Experiment 1, an analysis of first fixation proportion (FFP) revealed that both the prioritized and the accessory representations were able to capture attention suggesting a significant attentional guidance effect. However, such effect was not present in manual response times (RT). Most critically, in Experiment 2, we used a more robust experimental design controlling for different factors that might have played a role in shaping these findings. The results showed evidence for attentional guidance from the accessory representation in both manual RTs and FFPs. Interestingly, FFPs showed a stronger attentional bias for the prioritized representation than for the accessory representation across experiments. The overall findings suggest that multiple VWM representations, even the accessory representation, can simultaneously interact with visual attention

On the Common Neural Basis of Temporal and Spatial Dynamics of Attention: Evidence from Human Electroencephalography

This thesis investigated, by using electroencephalography (EEG) technique, the deployment of attention in time and space. Specifically –through three experimental chapters– Attentional Blink (AB) and visual search paradigms have been employed to highlight the common functional characteristics of the mechanisms which drive attention in time and space. In Chapter 1, an overview of visual attention is presented. Specifically, I proposed a theoretical introduction regarding the two aspects of visual attention debated throughout the manuscript, namely, the AB phenomenon –that is an effect related to the temporal dynamics of visual attention– and visual spatial attention. Results presented in Chapter 2 show how temporal dynamics of visual attention are affected by the AB effect, by analyzing how detection and encoding of a target are influenced when salient visual information is presented in temporal proximity. In line with Chapter 2, the experiment presents in Chapter 3 merged together, in a single experimental design, the AB and the visual search paradigms. In this study, I investigated whether the deployment of visual spatial attention in space is prone to the same experimental manipulations which influence detection and encoding of targets in the AB paradigm. Given the results, to assess why temporal dynamics of attention are similar both for midline- and lateral- presented information, in Chapter 4 visual spatial attention has been investigated with a visual search task, by comparing the electrophysiological activity elicited by a lateral presented target vs. a midline presented target. Eventually, in Chapter 5, a general discussion highlights the main findings presented in this thesis, by considering them collectively, and by raising future proposals and questions in relation to the topics debated in these Chapters

Emotion-related impulsivity moderates the cognitive interference effect of smartphone availability on working memory

Although recent studies suggest that the mere presence of a smartphone might negatively impact on working memory capacity, fluid intelligence, and attentional processes, less is known about the individual differences that are liable to moderate this cognitive interference effect. This study tested whether individual differences in emotion-related impulsivity traits (positive urgency and negative urgency) moderate the effect of smartphone availability on cognitive performance. We designed an experiment in which 132 college students (age 18–25 years) completed a laboratory task that assessed visual working memory capacity in three different conditions: two conditions differing in terms of smartphone availability (smartphone turned off and visible, smartphone in silent mode and visible) and a condition in which the smartphone was not available and was replaced by a calculator (control condition). Participants also completed self-reports that assessed their thoughts after the task performance, positive/negative urgency, and problematic smartphone use. The results showed that participants with higher positive urgency presented increased cognitive interference (reflected by poorer task performance) in the “silent-mode smartphone” condition compared with participants in the “turned-off smartphone” condition. The present study provides new insights into the psychological factors that explain how smartphone availability is liable to interfere with high-level cognitive processes

The attentional blink impairs detection and delays encoding of visual information: Evidence from human electrophysiology

This article explores the time course of the functional interplay between detection and encoding stages of information processing in the brain and the role they play in conscious visual perception. We employed a multitarget rapid serial visual presentation (RSVP) approach and examined the electrophysiological P3 component elicited by a target terminating an RSVP sequence. Target-locked P3 activity was detected both at frontal and parietal recording sites and an independent component analysis confirmed the presence of two distinct P3 components. The posterior P3b varied with intertarget lag, with diminished amplitude and postponed latency at short relative to long lags—an electroencephalographic signature of the attentional blink (AB). Under analogous conditions, the anterior P3a was also reduced in amplitude but did not vary in latency. Collectively, the results provide an electrophysiological record of the interaction between frontal and posterior components linked to detection (P3a) and encoding (P3b) of visual information. Our findings suggest that, although the AB delays target encoding into working memory, it does not slow down detection of a target but instead reduces the efficacy of this process. A functional characterization of P3a in attentive tasks is discussed with reference to current models of the AB phenomenon

Dark Matter signals from Draco and Willman 1: Prospects for MAGIC II and CTA

The next generation of ground-based Imaging Air Cherenkov Telescopes (IACTs) will play an important role in indirect dark matter searches. In this article, we consider two particularly promising candidate sources for dark matter annihilation signals, the nearby dwarf galaxies Draco and Willman 1, and study the prospects of detecting such a signal for the soon-operating MAGIC II telescope system as well as for the planned installation of CTA, taking special care of describing the experimental features that affect the detectional prospects. For the first time in such a study, we fully take into account the effect of internal bremsstrahlung, which has recently been shown to considerably enhance, in some cases, the gamma-ray flux at the high energies where Atmospheric Cherenkov Telescopes operate, thus leading to significantly harder annihilation spectra than traditionally considered. While the detection of the spectral features introduced by internal bremsstrahlung would constitute a smoking gun signature for dark matter annihilation, we find that for most models the overall flux still remains at a level that will be challenging to detect unless one adopts rather (though by no means overly) optimistic astrophysical assumptions about the distribution of dark matter in the dwarfs.Comment: 10 pages, 4 figures, minor changes, matches the published version (JCAP

Examining wheat yield sensitivity to temperature and precipitation changes for a large ensemble of crop models using impact response surfaces

Impact response surfaces (IRSs) depict the response of an impact variable to changes in two explanatory variables as a plotted surface. Here, IRSs of spring and winter wheat yields were constructed from a 25-member ensemble of process-based crop simulation models. Twenty-one models were calibrated by different groups using a common set of calibration data, with calibrations applied independently to the same models in three cases. The sensitivity of modelled yield to changes in temperature and precipitation was tested by systematically modifying values of 1981-2010 baseline weather data to span the range of 19 changes projected for the late 21st century at three locations in Europe

All-sky Medium Energy Gamma-ray Observatory: Exploring the Extreme Multimessenger Universe

The All-sky Medium Energy Gamma-ray Observatory (AMEGO) is a probe class mission concept that will provide essential contributions to multimessenger astrophysics in the late 2020s and beyond. AMEGO combines high sensitivity in the 200 keV to 10 GeV energy range with a wide field of view, good spectral resolution, and polarization sensitivity. Therefore, AMEGO is key in the study of multimessenger astrophysical objects that have unique signatures in the gamma-ray regime, such as neutron star mergers, supernovae, and flaring active galactic nuclei. The order-of-magnitude improvement compared to previous MeV missions also enables discoveries of a wide range of phenomena whose energy output peaks in the relatively unexplored medium-energy gamma-ray band

On the Common Neural Basis of Temporal and Spatial Dynamics of Attention: Evidence from Human Electroencephalography

This thesis investigated, by using electroencephalography (EEG) technique, the deployment of attention in time and space. Specifically –through three experimental chapters– Attentional Blink (AB) and visual search paradigms have been employed to highlight the common functional characteristics of the mechanisms which drive attention in time and space. In Chapter 1, an overview of visual attention is presented. Specifically, I proposed a theoretical introduction regarding the two aspects of visual attention debated throughout the manuscript, namely, the AB phenomenon –that is an effect related to the temporal dynamics of visual attention– and visual spatial attention. Results presented in Chapter 2 show how temporal dynamics of visual attention are affected by the AB effect, by analyzing how detection and encoding of a target are influenced when salient visual information is presented in temporal proximity. In line with Chapter 2, the experiment presents in Chapter 3 merged together, in a single experimental design, the AB and the visual search paradigms. In this study, I investigated whether the deployment of visual spatial attention in space is prone to the same experimental manipulations which influence detection and encoding of targets in the AB paradigm. Given the results, to assess why temporal dynamics of attention are similar both for midline- and lateral- presented information, in Chapter 4 visual spatial attention has been investigated with a visual search task, by comparing the electrophysiological activity elicited by a lateral presented target vs. a midline presented target. Eventually, in Chapter 5, a general discussion highlights the main findings presented in this thesis, by considering them collectively, and by raising future proposals and questions in relation to the topics debated in these Chapters.Questa tesi ha investigato, attraverso la tecnica dell’elettroencefalografia (EEG), l’allocazione dell’attenzione nel tempo e nello spazio. Specificamente –attraverso tre capitoli sperimentali– il paradigma di Attentional Blink (AB) e quello di ricerca visiva sono stati impiegati per mettere in luce le caratteristiche funzionali in comune tra i meccanismi che guidano l’attenzione nel tempo e nello spazio. Nel Capitolo 1, viene proposta una panoramica in merito all’attenzione. Specificamente, ho proposto un’introduzione teorica riguardo i due aspetti dell’attenzione visiva trattati nel manoscritto, ossia il fenomeno dell’AB –che è un effetto relato alle dinamiche temporali dell’attenzione visiva– e l’attenzione visuo-spaziale. I risultati presentati nel Capitolo 2 hanno mostrato come le dinamiche temporali dell’attenzione visiva vengano modificate dall’effetto AB, analizzando come la detezione e il consolidamento di un target siano influenzate quando delle informazioni visive salienti vengono presentate in prossimità temporale. In linea con il Capitolo 2, l’esperimento presentato nel Capitolo 3 ha unito assieme, in un unico disegno sperimentale, i paradigmi di AB e di ricerca visiva. In questo studio, ho investigato se l’allocazione di risorse visuo-attentive nello spazio sia soggetta alle stesse manipolazioni che influenzano la detezione e il consolidamento dei target nell’AB. In relazione a quanto emerso, per valutare perché le dinamiche temporali dell’attenzione siano simili per informazioni visive presentate lungo la linea mediana verticale e lo spazio lateralizzato, nel Capitolo 4 l’attenzione visuo-spaziale è stata investigata con un compito di ricerca visiva, comparando l’attività elettrofisiologica elicitata da un target presentato lateralmente vs. un target presentato lungo la linea mediana verticale. Per concludere, nel Capitolo 5, una discussione generale ha evidenziato i risultati principali presentati in questa tesi, considerandoli congiuntamente, e suggerendo proposte di studio future in relazione ai temi trattati in questi capitoli