Giovanna C. Del Sordo

Research Interests

My research involves the study of human attentional processes, with the main objective of understanding how it relates to LC-NE (locus-coeruleus norepinephrine) system functioning. My current research focuses on three aspects of human attention: (1) how neural gain fluctuations influence performance during attentional tasks, using pupillometry as an index of LC-NE activity ; (2) the mechanisms underlying sustained attention, identifying the behavioral and physiological signatures that allow individuals to maintain engagement over time ; and (3) how individual differences in cognitive abilities shape attentional performance, with the aim of understanding why some people are more resilient to lapses than others. 

My dissertation research explored sustained attention (SA), particularly focusing on a distinction between what I termed “active” SA versus “passive” SA attention. In the existing literature, the terms "sustained attentiona” and “vigilance” are often used interchangeably, despite their different definitions. Sustained attention refers to the ability to maintain focus on a task over an extended period, while vigilance involves the readiness to detect rare and infrequent events. Although they share similarities, I propose that vigilance should be viewed as a specific subtype of sustained attention, rather than an equivalent construct. I introduce a division within sustained attention into two distinct subtypes: (1) active, characterized by continuous engagement with task demands, and (2) passive, which is more reactive and readiness-oriented.

Another area of interest I have is on the exploration-exploitation tradeoff, the cognitive balance between exploring novel options and exploiting known strategies to optimize decision-making. The LC-NE system has been linked to this tradeoff, and its activity can be monitored through pupillometry (an non-invasive method of measuring pupil dilation). The LC-NE is tightly linked to attentional states and behavioral states and I hope that this research can advance our understanding of LC functioning. 

Similarly, I am also interested in attentional performance, and more specifically, on the interaction between attentional performance and effort mobilization  (a.k.a. cognitive effort).  I am looking at how aware people are about their own attentional processes (meta-attention) while performing a sustained attention task, and how their confidence judgements correlate with their perceived cognitive effort. 

Apart from my own research, I am actively involved in collaborations across different fields, where I contribute to methodological design and statistical analyses. I also pursue work on data sharing and open science, examining how research practices can be improved to enhance transparency and replication.

Some of my research projects

ACTIVE VS PASSIVE SUSTAINED ATTENTION

Differentiating between active and passive visual sustained attention

My dissertation work investigated the possible distinction between two subtypes of sustained attention: (1) active sustained attention, which demands continuous cognitive engagement, and (2) passive sustained attention, characterized by vigilance and readiness for rare events. 

My rationale was that even though the terms "sustained attention" and "vigilance" are interchangeably used in the literature to mean sustained attention, they do not have the same exact definitions. Therefore, I postulated that vigilant attention should be seen as a subtype of sustained attention. The experiments conducted aimed to differentiate these two forms of attention. Active sustained attention was assessed using a traditional Multiple Object Tracking task (renamed Active-MOT), while a modified version of this task was developed to measure passive sustained attention (Passive-MOT).

My dissertation is available on ProQuest here. 

Pupillometry Reveals Distinct Signatures of Active and Passive Sustained Attention 

To further test the distinction between active and passive sustained attention, I conducted a pupillometry study using both versions of the Multiple Object Tracking (MOT) task. This approach allowed us to examine not only behavioral performance but also the physiological markers of cognitive engagement associated with each attentional mode.

Our preliminary results are highly promising. Active sustained attention showed a profile of continuous, internally driven engagement, with pupil responses and performance varying systematically with task difficulty and remaining stable over time. In contrast, passive sustained attention was marked by low engagement until critical events occurred, suggesting that attention was triggered externally rather than maintained internally. Together, these findings provide converging evidence that active and passive sustained attention rely on different underlying control mechanisms—one sustained and self-initiated, the other transient and stimulus-driven.

Early results from this project were presented at Research and Creativity Week during the Undergraduate Research & Creative Arts Symposium (URCAS) on April 25, 2025, by Mayte Alonso Carrillo, a student in the Discovery Scholar Program at NMSU. Mayte received an award for Best Poster Presentation. I later presented the finalized findings in a research talk at the 66th Annual Meeting of the Psychonomic Society in Denver, CO, in November 2025.

EXPLORATION-EXPLOITATION TRADE-OFF

Exploration vs. exploitation in a novel complex card sorting task: Insight from pupillometry.

The exploration-exploitation tradeoff is a key element of Adaptive Gain Theory, suggested to promote the optimization of behavior toward high performance. This tradeoff is closely related to the phasic and tonic modes of the locus coeruleus-norepinephrine (LC-NE)  system.

To measure exploration and exploitation using a paradigm with tonic (baseline pupil size) and phasic (task-evoked pupil response) recordings, the present study used a novel Complex Card Matching Task (CCMT).

In this task, participants classify cards according to different, unspecified rules, Participants learn complex classification rules through trial and error using correct-incorrect feedback. This task taps into cognitive flexibility, as participants switch between exploration trials (i.e., testing new rules) and exploitation trials (exploiting the rule that currently applies). Two versions of this task were created to manipulate task difficulty. The “easy” version of the task has rules made up of three possible characteristics: color, shape, and number of shapes. Participants must classify cards according to six possible rules defined by consistencies across one or two features. In the “difficult” version, we added another characteristic (size of the shapes). In addition to the six rules in the easy version, this adds four more classification possibilities.

Our findings showed that exploration was associated with larger pupil size than exploitation, suggesting heightened LC-NE activity during uncertain decision-making. This effect was observed in both pretrial and task-evoked pupil responses, although task difficulty moderated these relationships. Pretrial pupil size remained consistent across difficulty levels, whereas task-evoked responses varied with difficulty, with higher task difficulty leading to greater pupil dilation in both exploration and exploitation. The pupil dynamics observed in the exploration-exploitation tradeoff highlight the complexity of this process, indicating that it cannot be fully explained by a single theoretical framework. 

The CCMT is available for research use on GitHub (both a behavioral and pupillometry versions): https://github.com/giovannacdelsordo/Complex-Card-Matching-Task.git 

Check out the manuscript here (published in Cognitive, Affective, & Behavioral Neuroscience).