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The factors of efficient visual foraging
The factors of efficient visual foraging
In this research project, we are interested in the strategies used to explore efficiently a complex visual scene composed of multiple targets and multiple distractors. In situations in which individuals search for different targets simultaneously (e. g., all the red dots and green squares in the display on the right), while avoiding distractors (e. g., red squares and green dots), some people exhaust one entire target category before switching to the second target category, while others gradually proceed in the visual space keeping the two target categories in working memory throughout the experiment. This research project aims at identifying the factors influencing foraging strategy and performance. Recently, we have also been investigating individual differences in visual foraging.
Since 2025, this research is part of the MULTIFOR project funded by the French National Research Agency: https://anr.fr/Project-ANR-24-CE28-3988
Related recent publications:
Haggouch, M., Doré-Mazars, K., & Tagu, J. (2026). Visual foraging and individual characteristics: Contribution of executive functions and personality. Acta Psychologica, 270:107773, 1-13. [online version] [pdf]
Tagu, J., Robert, C., & Mathey, S. (2025). Foraging through emotions: Emotional stimuli and participants' trait anxiety shape visual foraging. Royal Society Open Science, 12(5):242175, 1-12. [online version] [pdf]
Tagu, J., & Kristjánsson, Á. (2022). The selection balance: contrasting value, proximity and priming in a multitarget foraging task. Cognition, 218:104935, 1-12. [online version] [pdf]
The role of action in space-number associations
The role of action in space-number associations
The link between space and number processing is widely reported in the literature. In the brain, numbers are represented on a mental number line that facilitates the processing of small numbers in the left hemispace and of large numbers in the right hemispace. These "space-number associations" are observed through their influence on action parameters (reaction times, action magnitude). In this research project, we aim at demonstrating that action can, in turn, influence number representations, independently of the influence of space.
Related recent publications:
Tagu, J., Pressigout, A., Lemoine-Lardennois, C., & Doré-Mazars, K. (2026). The critical role of action in space-number associations: Evidence from random number generation. Psychological Research, 90(2):53, 1-9. [online version] [pdf]
The development of pseudoneglect during childhood and adolescence
The development of pseudoneglect during childhood and adolescence
Pseudoneglect refers to a behavioral phenomenon characterized by a subtle but consistent bias in visuospatial attention towards the left side of space. This leftward bias is generally attributed to the right hemisphere’s dominance in spatial attention. This spatial bias is most commonly measured using a line bisection task, in which participants are asked to mark the midpoint of a horizontal line. The spatial bias measured in adults also reflects the integration of non-spatial factors, such as hand preference, eye dominance, and the hand used to perform the task. These factors interact and modulate both the magnitude and direction of the bias. In this project, we aim at better understanding the emergence and developmental trajectory of this spatial bias during childhood and adolescence, in relation with the development of handedness and eye dominance.
This project is funded by the Institute of Education of the University of Bordeaux and is conducted in collaboration with Dr. Laure Zago (Univ. Bordeaux, IMN-GIN).
Functional asymmetries in vision and oculomotor control
Functional asymmetries in vision and oculomotor control
This project aimed at examining how perceptual and motor asymmetries can influence attentional and oculomotor processes. Functional asymmetries such as the lateralization of visuo-spatial attention networks and the lateralization of local and global processing of visual information were considered. In other studies, we also examined how lateral preferences, such as handedness and sighting eye dominance, could play a role in perceptual and visuo-motor processes. To do so, we measured saccadic parameters in the left and right visual hemifields, in individuals with left or right handedness and sighting eye dominance. As shown in the graph on the right, our results for example showed that saccade accuracy (measured in a global effect paradigm) is higher in the hemifield contralateral to the dominant eye than in the ipsilateral hemifield. Such results are discussed with regards to the neural architecture of the oculomotor system, and we showed that eye dominance and perceptual asymmetries should be considered in future models of oculomotor control.
Related publications:
Jóhannesson, Ó. I., Kristjánsson, Á., & Tagu, J. (2022). Contrasting attentional biases in a saccadic choice task. Experimental Brain Research, 240(1), 173-187. [online version] [pdf]
Tagu, J., Doré-Mazars, K., & Vergilino-Perez, D. (2020). Saccade accuracy as an indicator of the competition between functional asymmetries in vision. Experimental Brain Research, 238(2), 411-425. [online version] [pdf]
Tagu, J., Doré-Mazars, K., Lemoine-Lardennois, C., & Vergilino-Perez, D. (2016). How eye dominance strength modulates the influence of a distractor on saccade accuracy. Investigative Ophthalmology & Visual Science, 57(2), 534-543. [online version] [pdf]
Quantifying eye dominance strength with oculomotor performance
Quantifying eye dominance strength with oculomotor performance
Contrary to handedness, which is assessed on a continuous scale with questionnaires, sighting eye dominance is assessed with tests (e. g., “hole-in-card test”) providing a binary measure: left or right dominant eye. Here, we showed that performance at basic oculomotor tasks (reactive and voluntary prosaccades) varies with the degree of eye dominance strength. Hence, this research projects aimed at computing a continuous scale of eye dominance strength based on oculomotor performance. One of our study for example showed that classic saccadic asymmetries between nasal and temporal hemifields, or between centripetal and centrifugal saccades, are associated with weak eye dominance. Based on these results, we have computed a continuous scale of eye dominance strength, where strong saccadic asymmetries is associated with no eye dominance and no saccadic asymmetries with very strong eye dominance (see figure below; %EDS-NTA refers to percentage of eye dominance strength based on the naso-temporal asymmetry). Overall, this research project involved both group-level and individual-level analyses. The obtained results are interpreted in relation with the neurophysiological bases of saccadic asymmetries and eye dominance.
Related publications:
Jóhannesson, Ó. I., Tagu, J., & Kristjánsson, Á. (2018). Asymmetries of the visual system and their influence on visual performance and oculomotor dynamics. European Journal of Neuroscience, 48(11), 3426-3445. [online version] [pdf]
Tagu, J., Doré-Mazars, K., Vergne, J., Lemoine-Lardennois, C., & Vergilino-Perez, D. (2018). Quantifying eye dominance strength - New insights into the neurophysiological bases of saccadic asymmetries. Neuropsychologia, 117, 530-540. [online version] [pdf]
Tagu, J., Doré-Mazars, K., Vergne, J., Lemoine-Lardennois, C., & Vergilino-Perez, D. (2018). Recentering bias for temporal saccades only: Evidence from binocular recordings of eye movements. Journal of Vision, 18(1):10, 1-16. [online version] [pdf]
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