Veronica Mazza

Veronica Mazza is a researcher. She is interested in visual perception, attention and human electrophysiology. In her research she tries to understand how the visual system selectively individuates and identifies the relevant objects presented in a cluttered scene. She addresses this question mainly through electrophysiological and behavioral measures in human adults.

Research projects

1) How does the visual system individuate the relevant objects in a scene?

It is still debated whether attention acts through enhancement of the relevant stimuli or through suppression mechanisms that filter out the irrelevant information. We study whether an attention-related electrocortical response, named N2pc, is unequivocally linked to distractor-suppression mechanisms. The experimental evidence accumulating thus far seems to challenge this notion, suggesting that the N2pc indexes mechanisms involved in localizing relevant stimuli in a scene through enhancement of their features and not suppression of distractors.

2) Does multiple target individuation operate in a mandatory fashion, or is it a flexible mechanism that depends on task demands? What is the impact of perceptual grouping on this mechanism?

By means of electrophysiological measures we investigate whether the visual system mandatorily tags all relevant elements or whether multiple target individuation is task dependent, being sensitive to the perceptual/cognitive operations required for the execution of a task. Given that the ability to selectively individuate the relevant objects in the visual field is tightly related to their tendency to group together, we additionally assess the impact of grouping on multiple object selection.

3) What is the interaction between the individuation and identification mechanisms during the execution of different tasks? What are their spatio-temporal brain dynamics?

According to several theories of vision, there are two separate stages of visual analysis. A first stage (individuation) distinguishes each relevant object as separate from the others on the basis of a coarse representation of their spatio-temporal properties, while a second stage (identification) encodes the objects in greater detail for full recognition and identification. We are currently investigating the involvement and interplay of these two mechanisms in a variety of tasks, ranging from present/absent decisions to discrimination and quantity estimation judgments. By means of a multimodal neuroimaging approach involving simultaneous EEG-MEG and EEG-fMRI recordings, we additionally aim at exploring the temporal and spatial features of brain activity involved in individuation and identification of multiple objects.

4) What is the role of irrelevant memory contents in target selection?

We study whether the contents of visual working memory can guide attention deployment to the visual field, even when they are totally irrelevant and potentially detrimental to target selection. By looking at ERP modulations in the presence of distractors resembling the memory contents we explore the neural correlates of the interactions between memory and attention.

Selected publications

Mazza, V., Dallabona, M., Chelazzi L., & Turatto, M. (2011). Cooperative and Opposing Effects of Strategic and Involuntary Attention. Journal of Cognitive Neuroscience, 23, 2838-51.

Mazza, V., & Caramazza, A. (2011). Temporal brain dynamics of multiple object processing: the flexibility of individuation. PLoS ONE, 6, e17453.

Mazza, V., Turatto, M., & Caramazza, A. (2009). Attention selection, distractor suppression and N2pc. Cortex, 45, 879-890.

Mazza, V., Turatto, M., & Caramazza, A. (2009). An electrophysiological assessment of distractor suppression in visual search. Psychophysiology, 46, 771-775.

Mazza, V., Turatto, M., Umiltà, C., & Eimer, M. (2007). Attentional selection and identification of visual objects are reflected by distinct electrophysiological responses. Experimental Brain Research, 181, 531-536.

For the complete list of publications, visit U-Gov catalogue, here.