PhD Student in Cognitive Science, University of Florence
Current research and interests
- Visual stability
- Eye movements
- Classification Images analysis
- Time perception
Panichi, M., Burr, D., Morrone, M. C. & Baldassi, S. (2012). Spatiotemporal dynamics of perisaccadic remapping in humans revealed by classification images,J Vis, 4 (12), 11. PDF
We actively scan our environment with fast ballistic movements called saccades, which create large and rapid displacements of the image on the retina. At the time of saccades, vision becomes transiently distorted in many ways: Briefly flashed stimuli are displaced in space and in time, and spatial and temporal intervals appear compressed. Here we apply the psychophysical technique of classification images to study the spatiotemporal dynamics of visual mechanisms during saccades. We show that saccades cause gross distortions of the classification images. Before the onset of saccadic eye movements, the positive lobes of the images become enlarged in both space and in time and also shifted in a systematic manner toward the pre-saccadic fixation (in space) and anticipated in time by about 50 ms. The transient reorganization creates a spatiotemporal organization oriented in the direction of saccadic-induced motion at the time of saccades, providing a potential mechanism for integrating stimuli across saccades, facilitating stable and continuous vision in the face of constant eye movements.
Pascucci, D., Megna, N., Panichi, M. & Baldassi, S. (2011). Acoustic cues to visual detection: a classification image study,J Vis, 6 (11), PDF
A non-informative sound is known to improve contrast detection thresholds for a synchronous visual target (M. Lippert, N. K. Logothetis, & C. Kayser, 2007). We investigated the spatio-temporal characteristics of the mechanisms underlying this crossmodal effect by using a classification image paradigm specifically suited to investigate perceptual templates across both space and time (P. Neri & D. J. Heeger, 2002). A bright bar was embedded in 2D (space-time) dynamic noise and observers were asked to detect its presence in both unimodal (only visual) and bimodal (audio-visual) conditions. Classification image analysis was performed and the 1st and 2nd order kernels were derived. Our results show that the cross-modal facilitation of detection consists in a reduction of activity of the early mechanisms elicited by the onset of the stimulation and not directly involved in the identification of the target. In fact, the sound sharpens the 2nd order kernels (involved in target detection) by suppressing the activation preceding the target, whereas it does not influence the 1st order kernels. These data suggest that the sound affects some non-linear process involved with the detection of a visual stimulus by, decreasing the activity of contrast energy filters temporally uncorrelated with the target, hence reducing temporal uncertainty.
- Panichi M, Morrone MC, Burr DC, Baldassi S. (2010) “Spatiotemporal mechanisms of perisaccadic vision revealed by psychophysical reverse correlation”. Perception 39 ECVP Abstract Supplement 2010. European Conference on Visual Perception 2010. Lausanne (CH). [Talk]
- Panichi M, Megna N, Baldassi S. (2009) “Spatial frequency affects perceived temporal duration”. Perception 38 ECVP Abstract Supplement 2009. European Conference on Visual Perception 2009. Regensburg, GE. [Poster]
- Pascucci D, Megna N, Panichi M, Baldassi S. (2009) “How does sound improve vision? A classification image study”. Perception 38 ECVP Abstract Supplement 2009. European Conference on Visual Perception 2009. Regensburg, GE. [Poster]
- Panichi M. “Studio della soppressione saccadica attraverso una tecnica comportamentale di monitoraggio dei movimenti oculari”. (Investigating saccadic suppression through the usage of a behavioral paradigm to control eye movements). Honours Thesis, University of Florence (2008).